How to identify and locate a parasitic drain

How to determine if a vehicle has a parasitic (key-off) battery drain and, if so, how to identify which circuit is causing it.

[@veridianmusic2084]

One thing that I would add: Before you hook your DMM into series on the negative side, you should hook a 10 amp (or whatever your meter is rated for) fused jumper wire in place of the DMM. If the fuse blows, you know that there is more current flowing than your meter can handle. It’s a simple step that is quick and easy and will save you a bit of grief when trying to locate the source of the drain.

[@JustinMillerAutomotive]

great tip!

[@zekyday8064]

Being an engineer, I can tell you that your videos are simply easy to follow. Thanks. Create more videos.

[@JustinMillerAutomotive]

Thanks!

[@johntingle455]

A

[@ryancornett7916]

This is the fifth video I've watched now on this subject and by far it was the most helpful and thorough.

[@JustinMillerAutomotive]

I'm glad it was helpful!

[@greghercher2068]

I've watched 4-5 of these videos on the subject and not a single one of them was anywhere near as good as this one. Well done and thanks for the good description.

[@windward2818]

Some tips: 1) After you defeat the switches and sensors to allow access to all of the fuse panels, the vehicle will need time to go to sleep. It would be good to know how long to wait before a current reading is actually the proper sleep current or sleep current + a parasitic draw, so if you work on the same make of vehicle it might be helpful to test a "normally" working car to see what the sleep current and sleep timing actually looks like. Also, it is helpful if you ask the customer how the car is left after driving. If it is parked in a garage it may not be locked. A max normal sleep current is most likely 50mA or less although it really depends on the vehicle and accessories. 2) It is easier to use a clamp meter as an initial test, like the B&K Precision Model 316, which has a 1mA resolution on the 10 Amp range. The real challenge to using the 316 clamp meter is to get the jaws around all of the battery feed cable. 3) Once the vehicle is asleep if you disconnect the battery the vehicle will reset and the problem may go away after you insert the DMM. If you want to install a shunt (DMM) into the circuit do so in such a way that you do not break the circuit. DMMs have the disadvantage of having a burden voltage when reading current, and if overloaded may blow a fuse. Some perisitic draw problems actually require a key on to key off sequence to recreate the problem the vehicle may draw more than 10 Amps if you go key on. 4) Parasitic loads are not necessarily static in nature, they may be periodic or have a more complex waveform. If I see my clamp meter reading jumping around I know the parasitic draw current is dynamic. To get a better idea of what is going on I use my Fluke Scopemeter and Fluke current probe, both are battery operated, to understand the current signature. 5) Another issue with doing parasitic draw troubleshooting is usually when the problem shows itself the vehicle will usually not start without a jump. So when it arrives at the shop the battery is almost dead. Charging the battery fully to a point where it can be relied upon to provide enough energy to complete the testing will take time. A quicker option is to put the vehicle on "life support". I use a linear DC power supply with current limit and reverse current blocking diode (much like what is in the old fashion chargers called a rectifier or stud mount diode and heatsink). I can then increase the system voltage from the battery or jump start posts, so I can do my testing without the battery going dead. I can actually put a slight charge on the battery while I do my testing. Much like you may do when reflashing modules in a vehicle. I like the linear DC supply over a DC switcher because it has about 50 times less ripple or noise. 6) Parasitic draw troubleshooting is difficult to teach because the problems are so diverse. So it is helpful to have many different approaches to identifying the cause.

[@ravineseder3133]

Excellent! No useless commentary or super-dummy-level instruction like every other video-maker, he just gets right to the point.

[@albieviciouz4198]

by far the most helpful useful video that actually works! THIS IS THE WAY they brought me a ford f250 with parasitic draw they took it to 2 different shop and could not find anything. thanks to this video step by step i followed and solved the issue. thank you for this awesome video

[@AndrewSteitz]

I like measuring the mV across the back of the fuses instead of removing fuses to see if the Amp draw drops like it says in other videos. In my case I KNOW there is a parasitic draw because I just got a new battery a few days ago and after letting car sit a few days (with everything off and all doors closed) so I won't need to mess around with disconnecting the battery cable to hook up the meter in series, I can just go straight to measuring the voltage across the fuses. Brilliant idea.

[@timleary493]

Cantfigurewhyampormv

[@urdulearner8221]

Great video and great explanation. I wish you went further where you finally would overcome the drain !

[@jimmywells33]

Would be awesome if there was a second part to this video showing how you tracked down the draw after figuring out what circuit it was on.

[@andrewhoward7200]

Really useful. Especially the tip about not removing the fuses. Thanks.

[@russiandrivers9986]

Excellent video. The way you explain it makes it easy to understand. Before I was confused as to why people were measuring a voltage drop instead of pulling the fuses and measuring amps.

[@numinous4789]

I've heard the rule of thumb vary from 30mA to 50mA. It really depends on the spec range of the car. Good vid.

[@JustinMillerAutomotive]

You're right. It all comes back to the guideline that says that a 1-amp drain over a 24-hour period will typically drain a fully charged battery to the point that it won't be able to start the car. So, a .5-amps drain would take 48 hours, a .25 amp drain would take 96 hours (4 days), and so on. Based on this math, a 50mA drain would prevent the car from starting after 20 days of sitting, and a 30mA drain would take 33 days. Not to mention that a battery's life is shortened when it spends any amount of time sitting in an undercharged state. I guess the best rule is that the lower the drain is, the better your life will be!

[@Darren1983uk]

Thanks for the great vid, i'm a newly qualified level 3 technician and I have a lot to learn still I know but your vids are giving me extra diagnostic procedures to carry out and understanding. Cheers bud!

[@anthonybronson8231]

Bravo Justin you have made my day so simple and works thank you sir excellent fast and simple no momble jomble crap talk awesome....

[@davegoud]

Awesome vid....the only thing i would add is if you have a large parasitic draw like in this video I usually start by disconnecting the alternator before going to the fuse box. From past experiences of bad diodes in alternators even if you pull all the fuses the drain remains

[@davidcrandon2329]

Aha! Maybe this is my issue. I have a Honda S2000 which has a parasitic draw of 0.4A that continues even if all the fuses are pulled. Before I test the alternator, do you any other ideas of components that can draw but don't go through fuses?

[@izzys5745]

Excellent video, most informed video on this problem. Wish all videos were this articulate. Will try this out, have had this problem with many cars and could never find a good video on parasitic drain. Thank you

[@edsalvador5939]

Thank you I learned more from video like this then I do at my work shop. I am going to level 2 this year for automotive technician

[@AlphaAquilae]

Thanks a lot! Recently my car drained out battery over night. After watching your video I've found that ABS is draining almost 2 amps. It turned out that ABS fuse and contacts in fuse box has been oxidized. Also last few months ABS light on dashboard popped out a lot. Now I know what was causing that.

[@azclaimjumper]

I've just subscribed & rang the notification bell. Your video was my guide in tracking down a parasitic grain on my neighbors vehicle. Thank you. I've searched for a Battery Disconnect switch, however, I was unable to find one with small pins for connecting small alligator clamps to it.

[@JustinMillerAutomotive]

Maybe it is not available where you live, but I purchased my disconnect tools on Amazon or Ebay.

[@nealcordova1103]

Clear voice and precised demonstration very easy to understand. Good job men.

[@kennymason7648]

Thank you sir, following your teaching, I was able to identify the problem, faulty radio circuit.

[@snaproll94e]

Good video. One small observation and you fixed this at the end of the video but didn't point it out. When using vice grips, don't connect the meter lead to the handle that releases it. That handle is loose and floats on pins so it may not provide a good connection which could give erroneous readings. It is much better to connect to one of the outside handles or better yet, one of the jaws touching the post. Thanks for the video.

[@brentcolons6621]

you have the MOST comprehensive and thuro parisitic drain testing in all of youtube. thankyou sir. subscribed.

[@JustinMillerAutomotive]

I'm glad it is helpful! Thanks.

[@brandonsibley8528]

I've searched & watched videos on this for about an hour. You were the only one that explained where & how to hook up the circuit tester & with great focused video. TYTYTY

[@JustinMillerAutomotive]

Thank you. I'm glad it helped!

[@albievicious]

Wow such a detailed amazing video by far the most efficient and reliable video

[@azmalu]

Thank you for documenting this and making it simple to understand !

[@wikkedfun]

Thank you. That was excellent with an absolute minimum of idle chat and all of the details needed to do it right. And ditto to "urdu learner" the next step would be a useful followup video - yeah I realize every fuse leads down a different rabbit hole ... but maybe one of the simpler or most common ones?

[@JustinMillerAutomotive]

Great suggestion. Thank you!

[@crpth1]

Arion Stone - Opinions may vary but based on personal experience. The most common cause for parasitic drain in the electrical system are: 1 - Botched work done on the vehicle, mostly associated with sound/media/entertainment. 2 - Wires and/or connectors damaged during interventions be it for normal maintenance or anything else. Bumping or pulling wires or connectors is a big no no, on ANY electrical system. 3 - Components failure. With in component failure a huge number is associated with dirt/corrosion. My 2 cents. ;-) Cheers

[@alm7707]

great video Justin Miller. I have found that on older cars that have had a remote car starter installed that it is the remote starter box that is drawing current. Seems when they get old they don't shut down or something. Check that the alternator isn't the problem. I'm just working on a semi with 4 -1125 amp batteries that go dead in a week.

[@barelywoke7114]

AL M --I have an old truck with shaved door handles. The receiver was my drain. The receiver is similar to a remote start keyless entry module. Thanks for the tip!

[@rahrah8076]

You explain everything so well and it’s very easy to follow and understand..

[@tbirdpimp07]

Real slick man i woud have never thought to watch volt drop across fuses thanks for posting

[@PTran-ng6gl]

May check for blow fuse?

[@PIANOSTYLE100]

Cody..I am a former electronic tech.. That would have come in handy years ago. I even saw where somebody was using 1 ohm resistor ..dont remember how it was used.. but the voltage was supposed to be current of the fuse. I have not tried it..

[@ismaelmelendrez3747]

Good video but i've been taught at the nissan training center not to completely remove the battery terminal until the dmm is connected in series. This way you dont accidentally kill a intermmitent drain for example a relay

[@rms5654]

Good idea!

[@smid2550]

when you found the circuit that was leaking voltage, why didn't you pull the fuse to see if the amp draw dropped?

[@alabaiCA]

Good question. When you pull it out the drain should stop...

[@TheFatNumpty]

@@polarlab113 why? I didn’t see the part where he pulled the fuse either, they just skipped right to the part about that shutoff device thing?

[@wolfjay1343]

When You Pull A Fuse Out It Can Wake Up Other Circuits And Cause The Amperage To Spike Causing You To Record It Incorrectly

[@yungtomb9374]

​@TheFatNumpty so what are you lost on if you find the bad circuit you can just pull that fuse for temporary relief depending what that fuse controls youll then start looking at the wiring diagram to that circuit. So say it the fuse for horn was drawing power then youd follow the horn, wiring and everything inbetween and repair that actuall issue. He explains it pretty straight forward.

[@yungtomb9374]

​@@TheFatNumptyright around 8:40

[@demasterafrica8013]

Thanks man, you'r plan works, I had the same problem in South Africa

[@zamzammrfixit3113]

Kool

[@KeithSWD]

These guys are great! i no longer rush to our RSA tricky mechanics nowadays.

[@rolandbrooks386]

Check voltage drop on each battery post to its respective cable as well... Nice video, and thanks for your time

[@alangranados7436]

Thank you for your intuitive information I currently have a situation with my 2016 Ford Explorer it is having a parasitic draw on the PCM power relay I currently check fuses I pulled the 10 amp fuse that looks like the one in your video in the exact same position in the relay finally Powers down just curious if you would have any information on that situation thank you

[@marionamewontwork2681]

Good video, I also just watched erics. Im actually going crazy with my truck. It can sit for 1-2 weeks and start fine but then the next day it has a dead battery. I have put in a new alternator and battery. Have also had it at 2 different garages. No one can figure it out. Im starting to lose my mind.

[@TheJhaley12]

Excellent video, best I've seen. I sure wish you guys could work on my Ford Escape, no one around here has a clue how to find and fix this problem.

[@AceDublB]

TheJhaley12 Did you ever find the problem, I have a 2009 Ford Escape, hoping it isn’t the Alternator as it is expensive.

[@AlexAndreiZAR]

You should have connected red (+) voltmeter connector to ground (-) connector of vehicle and the black (-) voltmeter connector to the negative (-) connector of the battery to avoid getting a negative value reading like you show us. Also you mentioned about the door latch to be closed so that the car thinks it is closed and ECU's go to sleep, but you might need the trunk open as well (if you have a 3rd fuse panel which is in the trunk) and also you need to close the hood latches as well. Thanks and good luck!

[@shimmeringreflection]

Doesn't matter if you connect them in reverse -- he knows the negative reading is actually positive. And he knows in this car it only has one fuse panel

[@EM-cz4rd]

@@shimmeringreflection true but those of us with ADD won't have it LOL

[@Jajatube1]

you are a great teacher, keep making more videos.

[@rosefollet4700]

my Honda Odyssey developed a parasite. This video gave me a lot of info. much appreciated. Keep up the good work!

[@RND-USA]

This is such a great video but did you find out where the drain was coming from!? The suspense was killing me! 😂

[@mortvid]

Justin I own a Euro shop and have fought with under dash fuses trying to hold both leads with a single hand and making a good contact across the fuse while watching the meter for years. It's like holding chopsticks and after 40 fuses or so behind a glove box your hand will have cramps and you will be ready to say screw this car. I was looking for a better lead to bridge the fuses in tight spaces and stumbled across a very smart technique from another techs thinking out loud that changed the game. They make things like the calvan amp hound and tweezer type connectors to make it easier to get on both sides of the fuse but under a dash it's still a royal pain. So here it is. Find an empty fuse hole in the block that is live with key off on the power buss side and stick a spade connector in it. Run it to your plus side of your tester. If you can't find this just run the lead to any battery plus connection up to and including the battery +. Now you can test all the fuses in the block with only the negative lead in hand having only to make one connection on the cold side of the fuses. Readings are identical to checking across each individual fuse. There will be a third thing you will see though besides dead zero and a small miliamp reading. When you check a fuse that is not hot with the key on you will usually get some type of a ground through the consumer on the circuit and your meter will read out of range for miliamps. This doesn't matter though because this circuit is not hot with the key off and isn't a suspect in your hunt for the parasitic draw. You can eliminate it. Enjoy!

[@JustinMillerAutomotive]

Great tip! That is a new idea that I have never thought of!

[@mortvid]

@@JustinMillerAutomotive One caveat Justin, the further you get from the fuse with your power source you may read higher milliamp readings on fuses with current flowing than if you measured across the fuse but that's ok. I don't use the miliamp conversion charts anyway. The dead ones will always read zero. Once you identify the fuse/fuses of interest you can use more precise pinpoint tests moving forward with the diagnosis. Hope that makes sense.

[@torylynn2913]

Love this video!!! Kept it simple and to the point!

[@thrustprop67]

Very clear instructions a well done helpful clip thanks a million

[@franklynpertuz7669]

Great video great explanation thank you your tips are awesome very grateful that you sharing this with us

[@nickayivor8432]

Good Morning Justin Miller take care and have a great day Justin Miller Thanks 👍 Tutorial great 👍 👍 👌 👏 From Nick Ayivor from London England UK 🇬🇧

[@RJ6AV6]

Thanks for making this video it absolutely helped! 👍👍

[@alibatebi2161]

very informing video. thanks. how about the other fuses that you didn`t check, what if one of those causing the drain.

[@JustinMillerAutomotive]

Typically, the larger fuses feed multiple smaller fuses, so you can usually find the problem in a smaller fuse, which would actually be closer to the problem. However, if none of the fuses seem to have current flowing through them, yet there is a parasitic drain, then it is time to get more serious. It sometimes means checking current flow through the larger fuses or unfused battery cables.

[@nickayivor8432]

PRODIGY Justin Miller My teacher Amazing what you know thank you very much for sharing what you know Take care and have a great day PRODIGY Justin Miller From Nick Ayivor from London England UK 🇬🇧

[@valibu71]

Great video not confusing at all, great job Thank You.

[@frankthornley4116]

very clear and well done. Thanks. Is there a follow up showing how to fix problems?

[@gopher280]

What a great video, helped to finally understand how to do this.

[@alancall5113]

great video bro explained so simple nice job

[@francanfix9149]

Thank you for the video,, easy and true.

[@thegrmcrckr488]

Great Video, but I have a question about the voltage drop across the fuse. Wouldn't you want to check the fuse using a multimeter with the ground being on the neg cable and then touch each fuse instead of trying to get a voltage drop across the fuse? Aren't you just measuring the drop of voltage across the fuse and not the voltage drop across the circuit?

[@JustinMillerAutomotive]

We actually are trying to measure the voltage drop across the fuse only. The voltage dropped will be in proportion to the current flowing through the fuse. If zero volts are dropped across the fuse, there is no current passing through it.

[@hillbillyb4u]

If you’re measuring current or voltage through a good fuse, you have a poor electrical connection where the fuse plugs in. If you want to measure the actual current on an individual circuit, pull the fuse and hook up your leads like you did at the beginning in series with the load.

[@JustinMillerAutomotive]

Removing the fuse is also likely to reset any computers in the circuit and possibly make an intermittent drain go away. You can measure current indirectly by measuring voltage drop. This uses Ohm's law. It is the same principle as using a shunt resistor to measure current. It is very accurate and non-evasive.

[@SteveRobReviews]

Great tips - IR thermometer gun works good as well but not on small ma. draws.

[@kencohagen4967]

Always set your meter higher than you expect the current or voltage to be, then you can set it lower if needed. Unless you have an autoranging multi meter you could damage the meter if you set it to low.

[@johncollins8304]

Fabulous camerawork and commentary. TX a lot!

[@oneminutetomidnight]

I can already see what's draining the battery bruh! The multi-colored underbody LED neon light system is still on! It looks so dope too!

[@thephilosopher4719]

Hi Justin Please help, I am facing a Parasitic Drain on my Elantra, i have 300 mA drain, i used a different technique of pulling fuses, and noticed that the "memory fuse" alone drain 100 mA, alone with some other AC fuses. I checked the items related to each fuse, and made sure all is turned off, but still drain available and it is too high! The funny part sometimes it drains and sometimes it doesn't, so sometimes when i turn on the car in the morning, it starts, and sometimes not, although i make sure everything turned off after switching the car off at night! What would you recommend me to do next?

[@crpth1]

Old question. But here it goes. Either the system is still live when you test it. Or probabilities point that, sometimes On, sometimes OFF, to a relay malfunction (stuck). It's worth mention that dirty contacts, particularly bad ground connection(s) don't help at all. ;-) Cheers

[@192ali1]

Thank you for your good and comprehensive video. If I may, have two questions to ask you about this video. 1) When you disconnect the negative battery terminal from car, then all electrical should not be functioning. Why should one be concern about the door of the car being closed? Once one of the terminals of the battery is disconnected then there should not be any current passing through wires. Am I correct? 2) Why did you connect the red terminal, the positive terminal of the volt meter to the disconnected ground terminal of the battery? Thank you

[@lyleb4399]

As soon as you connect the multi-meter in series, you've re-established the circuit and things turn back on.

[@masterdanprice2904]

Wow. That is very smart. Thanks for the power. Information is power.. one less trip to the mechanic

[@toastrecon]

I've also seen that there are charts you can get that will show the approximate current flow across a fuse of a particular type and current rating. So, you'd take that mV calculation and then look it up on that chart and it'd tell you about how many amps were flowing.

[@JustinMillerAutomotive]

That is true. I have one of those charts. However, after studying the chart, I came to the conclusion that any voltage dropped across any fuse above about 1 mV indicates an unacceptable amount of drain, so I have just taught people to watch for any reading that is not zero and pay close attention to any reading above 1 mv. I still refer to the chart occasionally to see how much current is flowing through a specific fuse. Thanks for the comment!

[@rectify2003]

Great explanation Subscribed

[@luthergarrett6389]

Justin, I don't think you can measure current across an un-blown fuse. it's the same as touching your two probes together. You "can" measure current across the fuse socket after you pull the fuse.

[@JustinMillerAutomotive]

We aren't measuring current across the fuses; we are measuring the voltage dropped across the fuse. If there is voltage being dropped, we can know that current is flowing through it.

[@armiaomidvar4687]

hi and thanks for the video it helped a lot , but quick question how do I fix it once I diagnosed the broken fuse? ( I'm not a mechanic btw, so pardon me if I sound ignorant)..

[@DesiRoti]

Great video, going to try to find out why my nissan qashqai is draining the battery through this method, but what do you do after you find a fuse that is draining the battery. do you change it, take out for good, how do you fix this problem, any thoughts?

[@JustinMillerAutomotive]

Ideally, you would be able to find a wiring diagram that tells you what is connected to that fuse. Then, you can begin isolating components in that circuit one at a time. For example, if the radio and auxiliary outlet are both connected to the fuse that has high current flow, you could disconnect the radio and see if the drain goes away. If not, you can disconnect the auxiliary outlet. If neither makes the drain go away, then there is something else connected to the circuit. Sometimes it is an aftermarket device that someone has wired into the vehicle.

[@davidm3210]

That was fantastic, thanks! I just wonder why there would be voltage drop across the fuse. I reckon it's the slight resistance of the fuse acting as a load, as voltage drop can only be measured in loaded circuits (drawing amps). But if the fault is downstream of the fuse would it still show up? If so, I don't comprehend the practice of tracking down the problem spot by moving along the circuit -I thought devices before the fault didn't show v.d. I fear my knowledge of this topic is incomplete -but great stuff, kudos.

[@JustinMillerAutomotive]

That is exactly right. Every conductor - even wires and fuses have a little bit of resistance and drop a little bit of voltage. However, voltage only drops when current is flowing. That is the reason we are looking for a voltage drop - because it indicates flowing current.

[@davidm3210]

@@JustinMillerAutomotive Thanks so much for the response! If I could prevail on you again, Is there a reason why one couldn't set the DVM to amperage and check for current at the fuse? Any thoughts on the fuse buddy?

[@JustinMillerAutomotive]

The biggest reasons that you wouldn't want to use your voltmeter's "amperage" setting is that you would need to remove each fuse one at a time to place the meter leads in series with the circuit. Not only would this be time consuming, as a rule, you do not want to remove fuses because it will disable and/or reset the computers on the vehicle, which could cause a lot of confusion or even turn your problem into an intermittent one. On a modern car with many interconnected computers, it is best to measure the voltage drop across the fuses without disrupting the current flow to anything. I tell people to "be stealthy" so that the car doesn't know you are there!

[@davidm3210]

@@JustinMillerAutomotive Oh I get it, one isn't in-line when they probe the contacts on the back of the fuse -now that I think about it, if they were, they couldn't perform a voltage drop test in the first place. I missed that & you have sharpened my comprehension. Thank you so much for your time & generosity of spirit!

[@donewithutube]

Super helpful. Thanks for taking the time to make this video.

[@aeromustang4054]

Good advice...I didn't know I could check those types of fuses like that...thanks

[@sephiroth7470]

do you have to have the first multimeter connected to the battery terminal/cable to test the fuses?

[@JustinMillerAutomotive]

No, you can remove the first meter, but you must reconnect the battery cable. If you happen to own two meters, it is just helpful to be able to see that the drain is still there while checking the fuses.

[@sephiroth7470]

@@JustinMillerAutomotive oh okay thank you for clarifying, great video by the way. very helpful :)

[@poisonduckee]

What about if you don't have a second multimeter? Do you then just hook the battery back up before you start testing the fuses? Also, with your setup of the multimeter being in series, will that have any effect on the results of the fuse testing?

[@JustinMillerAutomotive]

You are exactly right. You can reconnect the battery and then begin checking for voltage drop across the fuses. The multimeter in series will have no affect on current flow.

[@poisonduckee]

@@JustinMillerAutomotive Ok that's what I was thinking. However with the car I am testing there is an alarm that sounds when you reconnect the battery. But it doesn't sound when I have the multimeter in series. I get no reading on the meter. I dont expect you to diagnose through KZbin comments but I am lost lol

[@zaythegamer5962]

I'm having this problem with my 03 GMC 1500, when I find the parasitic drain, can I just remove the fuse and the problem is solved or is more to that...for example if it the radio fuse causing the drain can i remove the fuse and the parasitic drain problem is gone.. By the way...great video

[@dangerousdan9944]

I have the same question so am going to find parasite , pull it , and test with meter every other hour so the battery can be saved Iwont be stranded.Glade you asked that.

[@EGGINFOOLS]

If you don't want to use that circuit, sure. You may need that circuit to run the car or gauges. Depends on which fuse you pull

[@timtravasos2742]

So what was the source of that drain?

[@pauldesmond3269]

wouldve been nice to know

[@davesgarbage1]

great video. one question....I have a truck with 2 batteries. Do I unhook the ground on both batteries ? This is rather new to me. thanks

[@JustinMillerAutomotive]

You would need to disconnect both batteries, then reconnect only one of them through your meter.

[@quickdeuce]

I'm assuming the clock will be a draw and we already know this. Should we first ensure the clock is on a dedicated circuit and if so remove that fuse? If the radio is on a shared circuit then we'll need to detirmine the draw the clock needs and test to make sure there's not an excessive draw? Yes, removing the fuse will likely awaken the computer so may need to wait the time required (30 or so minutes?) for the computer to shut down.

[@JustinMillerAutomotive]

The clock and other computers in the car will always draw some current for their keep-alive memory. That is the reason that it is acceptable to have up to 30 milliamps of draw at all times.

[@pedrorojascervantes3928]

Would merely unplugging the hood open/ closed switch connector be an open position? Should you not jump the two contacts together with a short wire / paperclip to simulate a closed/ latched position?

[@JustinMillerAutomotive]

Usually on a door jamb switch, a closed door = open switch. This is also true of this hood switch. Therefore, unplugging the switch would give the ECU the same input as a closed hood or door.

[@pedrorojascervantes3928]

@@JustinMillerAutomotive Right...

[@davidlopez7209]

Way better than the explanation on Shrodinger's Box.

[@embreesmith7613]

sssshhh !! you will hurt Bernie's big ego

[@2tallB]

That dude is amazing but he goes into college course level detail, explaining WHY everything happens. Sometimes you just want instructions on how to do a simple test. ;)

[@adriannyasia]

by far the best explanation on KZbin.

[@JustinMillerAutomotive]

Thank you!

[@nigelkirk1683]

worked a treat, most helpfully presented, thank you

[@tnamen1307]

Very nice..my car 45 ah draw .05 amp on parasitic test when all doors are closed and everything is off. Is this too high since it drains very quickly in just 3 days only?????

[@veridianmusic2084]

Might be a bit late for this, but a draw of 0.05 amps is a 50 mA draw. 30 mA is considered excessive.

[@vladimiramador8178]

thank you amazing explanation

[@ptyptypty3]

great video, thanks Justin!!.. I"m wondering, what was the problem? What did that Fuse go to?.,.. thanks..

[@JustinMillerAutomotive]

It was a fuse to the interior courtesy lights. I had created this issue intentionally to simulate a parasitic drain by leaving the door switch closed.

[@ldm128168]

great video... I've been having a drain problem on my 2012 Camry. How do you keep from activating the car alarm each time you reconnect the battery? I finally disconnected the horns on my Camry to at least not have to listen to them. Is there a better way?

[@JustinMillerAutomotive]

You can use a memory saver when you are disconnecting and the battery. I have a video showing how to do that. Just make sure you remove the memory saver once you have your meter connected (the meter reconnects the battery cable). If the memory saver is left in while you try to measure parasitic drain it will give you bad numbers and mislead you.

[@elaztecamoreno]

What kind of leads are you using? Not the alligator clips but the actual leads on you dvom? Look different than the ones on my fluke.

[@TNT-ml1ll]

Hi Justin, I tried by removing negative plug and I'm getting 0.5 Amp parasitic draw. Then instead of removing all fuses I find easy to touch all fuses by leads but I didn't found any draw by touching fuses. I decided to pulling out fuses if I find but some of fuses are too hard to remove by fuse pullers. And I have one more query What about the medium size and big size fuses inside the hood fusebox. Do we also need to check those?

[@TNT-ml1ll]

I'm able to see draw of 0.5 Amp but can't be able to detect which system is draining. As I'm having airbag sign on dash does it have any correlation with any draw?

[@JustinMillerAutomotive]

Does the light stay on when the ignition switch is off? If so, then it probably has something to do with the drain. If you have checked every fuse (make sure you are aware of all of the fuse boxes in the car), and you didn't find anything, I would recommend starting at the battery cable. There are usually 2-3 cables coming off of the positive battery terminal. The drain is going through one of them. It could be your starter or alternator causing the problem. The starter motor doesn't have any fuses and the alternator fuse is likely one of the large square fuses that you can't probe with your multimeter. You could disconnect the starter or alternator to see if that eliminates the drain. For a drain that large, you could use a current clamp around each wire to identify which one has current flowing through it. As a general rule, you don't need to check the large square fuses because they usually feed current to the smaller ATC or ATM fuses. However, if you have tried all of the normal tricks and are still getting stuck, it is time to get creative. There IS a drain, so there IS a way to find it.

[@mrsanders835]

hey this is good video, strait to the point and informed, good job

[@raulelgrande5071]

Very good video, question is where I can buy the battery shutoff switch? And cost?

[@CantGetRight911]

Why should you start by measuring the amp draw from the battery first and not with the fuses? Couldn't you determine if you have a parasitic draw from the fuses instead thus eliminating a step?

[@JustinMillerAutomotive]

For me, it is just part of the logical problem-solving process. I want to know if there actually is a drain before I put effort into hunting it down. It rules out other variables and possible causes, such as an intermittent problem or a bad battery. You could spend a lot of time looking for a problem that doesn't actually exist.

[@sollykhan2385]

Do remember to check the state of the battery, its age, any contamination on its surface, or the cradle its sitting in🤔, make sure its fully charged, get a DROP check done(pole to pole discharge) to ascertain the usefullnes of the cells and overhaul condition, as often, a depleted cell/or generally a bad battery will give enormous grief, and time consuming misplaced effort.

[@AdrianJayeOnline]

that pair of pliers is going to add a resistance, which will effect the readings, pliers are also coated so not going to get a good connection.

[@JustinMillerAutomotive]

At the very most, the pliers will drop 1 millivolt. Your battery voltage can vary by an entire volt. Even brand new battery cables and multimeter leads will drop voltage. Because the current flow is low, the pliers will not have any measurable affect on your drain or your test results.

[@andyworku5128]

Awesome video..Thank you for your time and knowledge.

[@jimrossmeissl2726]

So, the first step is just to verify drain and you can just skip to the second step without disconnecting the negative, correct?

[@davidcrandon2329]

I have a 0.4A parasitic draw on a Honda S2000 that isn't going thru any of the fuses. Anything besides starter and alternator that could cause it?

[@JustinMillerAutomotive]

If you have any aftermarket devices in the car, they may be connected to the battery directly rather than through a fuse in the fuse box. If you can find access to a "power distribution" wiring diagram, you can use it to see how the circuits "branch" off of the battery. This can be helpful to narrow down which branch has the drain in it.

[@fhowland]

I have an S2000 with the same issue! Did you sort yours out?

[@MuhammadAli-su3oo]

Very much informative video, biiiig Thanks. I watched another video here on KZbin, a guy said.. removing and connecting -Ve terminal can cause of generating some Generic OBD codes. Kindly explain this matter of concern.

[@JustinMillerAutomotive]

Disconnecting the battery can cause a whole bunch of issues on modern cars. That is why I recommend using a memory saver when disconnecting the battery. Just make sure that you remove the memory save once your ammeter is in place and before you take your current reading.

[@MuhammadAli-su3oo]

Thanks of You

[@billfroelich628]

You pulled the pigtail of the hood switch, now put one wire in both pigtail whole to trick the car to think the hood is closed. thanks bill

[@JustinMillerAutomotive]

Yes. It depends on whether the switch is open or closed when the hood is open. In this case (and it is the same with most door jamb switches), a closed hood or closed door causes the switch to open. So, shorting the switch would make the ECU think the hood is open, when we want to cause the opposite to happen - to make it think that the hood is closed.

[@musterseeds1778]

Nice tip, good for learning tip.....thank you.. well straight forward..

[@cayrick]

Great video thanks!

[@alanedwards4114]

Superb!!!!! Just sorted my 2 cars. Thanks

[@jambo38]

can any multimeter be used, or does it need to have the built in 10amp fuse, thanks for the video

[@JustinMillerAutomotive]

To do it this way, you would need a meter with a built-in 10-amp or 20-amp fuse. There are are other, more technical ways to do it, such as with a shunt resistor, but this is really the simplest. You can purchase a decent meter with all the right features for about $35.