The Trainer #27: 3 Ways Of Finding The Cause Of Key-Off Battery Drain (Parasitic Draw)

[@zigudjigi7580]

More and more i love voltage drop. Love the teaching

[@warrenmoore3006]

You NAILed it(fooling modules with the UNinterupted Sequence about their battery continuity) with the 'Jumper Box!

[@brendanlawlor1906]

""""As an ex motor mechanic , with over 40 years experience , It was a pleasure to listen to , and watch your test procedures , well done and best regards from Ireland

[@MotorAgeMagazine]

Thanks!

[@Xera01]

Thanks for leaving this old video up. The third method beats all in my opinion. Can't wait to get started on Monday.

[@Jay-vi7el]

Love the way you teach with detail and show what your doing

[@jamesbarratt593]

Like the speed he talks. The level of volume he uses. The content. The way he does not detract from the point of the video. Good trainer. a motor AGE trainer

[@MotorAgeMagazine]

Thanks James!

[@jamesbarratt593]

@@MotorAgeMagazine please. I am a mobile mechanic and get bored of most videos except yours. Class

[@MrPixlink]

Thank you for your time and valuable teaching. Truly plain and simple. This teaching was made so much easier by your step by step process as I have been watching several of the video's on this subject here on Utube and this one has topped them all in my book. Marvelous, simply marvelous.

[@MrUbiquitousTech]

Just goes to show you never stop learning. Thanks for teaching me something new, excellent video.

[@DashRipr0ck]

I can not thank you enough for this video. I have this very specific problem with my car and surprise! here is a very specific video addressing my problem. Again, thank you Motor Age and I am subscribing! Have a nice day :)

[@MotorAgeMagazine]

Glad you found it useful!

[@Lexxie45]

Thank you very much for this video. I have the battery drain problem with my Nissan Maxima, it has a brand new battery in it but every day I have to use a portable battery to jump start it. Huge pain in the you know what. I don't have the tools to do these tests and even if I had I don't have enough confidence I could do them right, so I will have to take the car to shop but at least I won't sound like a total idiot when I tell them what needs to be done and they won't be able to take me for a ride with the price. Thanks again.

[@spierotti14]

The amperage increase happens when I have followed the appropriate steps to begin testing. I allow time for verything to shut down then I have my meter in series via quick disconnect adapter for draw testing and monitor the draw disconnecting main light switch when I disconnect it the amperage shoots up to 12.1 amps. Thank you very much for talking with me, even if I don't come to soution, I really appreciate having someone to bounce ideas.

[@neilreid9005]

Really good and clear video on parasitic draw which is a problem I'm trying to resolve on one of my cars. Thank you!

[@marionamewontwork2681]

Really good parasitic drain video. First one to mention keeping the vehicle powered to not shut off the parasitic drain. I have been to 2 garages and they can not find the issue. Im guessing they skipped that step if they even did the parasitic drain test at all (just learning all this myself now). My truck keeps randomly having a dead battery but sometimes it can sit for over a week and start fine. Its also sometimes running at 16v I have never been more frustrated in my life. Who ever heard of spending money on a vehicle to not fix it... (did some blind fixes so its on me i guess...)

[@jesserigs2647]

One of the most informative videos I've ever seen, good job and thanks

[@sksupply]

Finally a good way to do this. Have a jump box too. Also have a new NAPA battery, but I really hope I don't find a drain. Excellent presentation.

[@stuzman52]

Very nice presentation Pete!

[@MotorAgeMagazine]

First, the battery must be connected to the system. There can be no voltage drop unless current is flowing and that won't happen unless the circuit is complete. Second, make sure the system is timed out, no lights are on, no doors are open, no convenience systems (a/c, heater fan, radio) are on. EVERYTHING must be off. Last, your meter has to be accurate to read in this millivolt range. A cheap auto parts meter won't do the job. Hope this helps!

[@dickross1815]

Excellent video, thank you for the presentation!

[@hoagybob]

excellent presentation and by far the most sensible approach to this troublesome vehicular anomaly

[@juliangonzalez7044]

Booty

[@sidallen685]

The best video I have seen on this topic.

[@MotorAgeMagazine]

Thank you for the kind words!

[@MotorAgeMagazine]

Thanks for taking the time out to watch and comment!

[@MotorAgeMagazine]

400 ma is a lot of draw! It is important to be sure that all the onboard computers have timed out before you start hunting for the cause. This can take anywhere from 30 minutes to 8 hours, depending on the make/model. Are the doors/trunk/hood open when you measured the draw?The lighting module may be actively online. You'll need to see what the three fuses have in common, if anything, but I'd look at the fuse NOT related to the lighting circuit. I think that 80-15 drop is the one you're after.

[@rnginu59]

huge thanks for posting this video. ive been fighting a problem like this for months now, and with your video i think i found the problem! thanks again

[@MotorAgeMagazine]

That's why we do what we do! Thanks for taking the time to comment.

[@nigelclark7360]

Excellent way of finding this type of fault

[@spierotti14]

Its fuse 2.31 if youd like to check it out. Thank you again for taking time to talk with me. I got a few of yalls ase study guides a year or so ago, I still like to go back and read them sometimes.

[@MotorAgeMagazine]

Hey, we'll add it to the list and see what we can do. Unfortunately, no, the "After Hours" segment is no longer being done. Instead, we started "In The Workshop". Same idea, just pre-recorded. You can still participate in the live webinars, though! There are 23 of them this year! Just sign up for the newsletter. The link is on our channel page.

[@MotorAgeMagazine]

It's not the fuses, but something that the fuses supply power to that is causing your problem. You'll need a "Power Distribution" wiring diagram so you can see what the two fuses send power to. I'm betting that the battery fuse is sending power to the IOD fuse, and I'd start there. Be sure to allow the control modules enough time to "go to sleep" before you take your measurements!

[@MotorAgeMagazine]

Back from vacation, and had a chance to look over the diagrams. If you pulled a fuse and then put your meter in series to measure the current draw, that counts as opening the circuit and that could wake up a module. Go back to the three fuses and send me the millivolt reading you get on each.

[@williamraoshimabasimanebot1439]

Thnx a lot ; YOUR explanation is very clear and it will help me do away with the PARASITIC battery drain of my C200 and SLK 230

[@MotorAgeMagazine]

Glad to hear it!

[@williamraoshimabasimanebot1439]

thanx MOTOR AGE

[@MotorAgeMagazine]

Interesting idea Luke. Current, voltage and resistance are all related. It works across the fuses because the fuse is a known resistance. Using the battery connections, though, would introduce a variable resistance factor you really couldn't account for. And with the voltage drop reading so small (usually less than 20-30 millivolts depending on the fuse style) it would be enough of a variable to skew the test results.

[@spelunkerd]

I have an expensive amp clamp from Fluke, and I'm not very impressed with it's measurement accuracy at the kind of low DC amp draw in a typical parasitic drain situation. I'm glad to hear you have the same experience, since I wasn't too happy to be looking for another clamp. I think your idea to measure voltage drop across fuses is the best screening test to narrow the search.

[@seshachary5580]

VERY EDUCATIVE.THANK YOU REGARDS

[@dubTuube]

Awesome video. Thank you!!!!

[@TrueBlueEG8]

This is an excellent video, very useful information, thank you :)

[@MotorAgeMagazine]

Thanks for watching and telling us what you thought of it. Glad you found it helpful!

[@onegizmo01]

A Great video and presentation. Thank You

[@101bluesguy]

very nice video guy thanks I'll try these.

[@MotorAgeMagazine]

Thanks! Glad you liked it. Hope you find it helpful next time you're looking for a thief!

[@malcolmyoung7866]

Really great video and so well explained. My VW LT 35 van has a parasitic drain, unfortunately it also has a host of 'add on' accessories including a 'base box' of all things. Coupled to that LED and emergency spot lights for working at night, I think I may have some trouble finding which circuits these are 'fixed into' ....but at least I understand how to do this now. Many thanks once again...

[@MotorAgeMagazine]

It's just two 12v batteries wired in series, like a golf cart, to raise the supply voltage. Most of the techniques shown in the video will work just fine on these systems.

[@fatboy3516]

Outstanding, thanks for explianing.

[@MotorAgeMagazine]

The phone/charger is a load on the battery, right? So sure, it can be a factor in your draining battery. Check it out and keep us posted!

[@spierotti14]

I'm working on a 03 lincoln towncar and I'm confused about something. 1st off I have a draw reading on 3 different fuses? 2nd when measing amp at the battery if I disconnect fuse #1 the draw decreases from 400ma to 200ma, if I disconnect fuse#2 I'm down to 80ma and fuse#3 down to 15ma. I decided to chase the one wth the highest draw. It lead me to a lightin control module, I disconnected the harness there and I dropped from 400ma to 80ma...then...

[@MotorAgeMagazine]

Go back to the lighting control module you disconnected earlier. You'll need a low amp clamp and meter for the next step.Divide the wires at the connector in half (or as needed to allow the amp clamp to wrap around them) and measure the draw. What you are trying to do is isolate the ONE wire that is pulling that 400 ma. of current. You can then use the wiring schematic to see where that wire is going. Isolate that cause first. It could be a defective module.

[@MotorAgeMagazine]

You would think so, wouldn't you? But now, the fuse has a resistance and there will be a measurable voltage drop if current is flowing through it. Not much, you'll need to measure in millivolts, but it is there.

[@vincebauer4777]

nice video I have done that in the past I was just tell a guy in our shop to look for a drain that way yesterday

[@sogerc1]

Thank you, you really know your stuff. Using your voltage drop method I can't find anything in my car so I'm gonna stop worrying my battery voltage for now and I'll just wait and see if the battery will drain again. It did before, and I took it to the car electrician and he repaired two things but I still see my battery volltage dropping slowly.

[@MotorAgeMagazine]

And last question. How did you determine that these three fuses were involved in the drain? Did you measure voltage drop across them, or did you pull them to see what current flow did on your ammeter?

[@mikefoster3547]

I still use the direct reading method using my old Fox Valley 965 digital DDM meter with a shunt, still to this day gives me accurate readings. Sometimes old methods are still the best.

[@MotorAgeMagazine]

The only thing I see in common between fuses 31 and 30 is the trunk lid release circuit. Try disconnecting the solenoid in the trunk lock assy and see what that does to your millivolt reading. I really think that when you pull the fuse, you are waking up several of the modules. You can also use a

[@MotorAgeMagazine]

Before we go to all that trouble, measure the drain when all the modules are awake for comparison.

[@MotorAgeMagazine]

More than likely you "woke up" other modules on the car. Like I said earlier, it is imperative that you allow all the modules to go offline before you measure the draw. Keep us posted on your progress!

[@petertorro]

Very good teaching , one question of the third method , current drop measering. Some fuses are not with the 2 measure points. They are smaller as that You measure. How do you measure such kind of fuses

[@DTR0454]

pretty sharp, voltage drop never tried that during parasitic draw testing.

[@mcconn746]

Great video. Thanks.

[@iamher6422]

This was 10 yrs. ago. Kaweets now makes a sweet parasitic tester that makes this job a lot easier..

[@MotorAgeMagazine]

That is the 2013 Ford Taurus SHO! We got to take it for a week, courtesy of some friends at Ford.

[@pmikashus4848]

Very Good....! I felt like I was back in High School I Mr Ward's class

[@MotorAgeMagazine]

Thanks for watching!

[@MotorAgeMagazine]

If you have even a momentary break in the circuit when you switch over to the meter, you'll wake everybody up. And 12 amps with the switch disconnected? That's a lot of draw. Would need to study the schematic to figure that one out. What kind of meter are you using?

[@ozzstars_cars]

thumbs up. Good video

[@sammivaughn4306]

I have a 1997 Ford Taurus I've checked all fuses for the headlights I still have no headlights I have turn signals I have running lights I have flasher oncoming traffic headlight no dims no brights can you help

[@mobilemechman]

Thanks for the tips!

[@morrisonreggae8146]

Thanks for the tips . I found out two of my fuses were draining my battery .the fuses are 50amp( battery and 10amp ( I.O.D )what should I do next to fix the problem ? Replacing these fuses will fix my battery draining problem or not . Please your comment will be appreciated . Thanks

[@lukeclinch9928]

is there a way of testing for draw at the battery using voltage drop? So you can be sure you have a problem before going through all the fuses? Could you just do a quick test between the chassis/block and the negative post? Cheers, Luke.

[@Bamba1955]

Like the volt drop test, never thought about using it across the fuses, I found the same amp clamp using the Pico scope to be very accurate though.

[@MotorAgeMagazine]

Agreed, the low amp clamp coupled to any scope is more stable than the signal rec'd by most digital multimeters.

[@markslusz5590]

Great job!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Thank you!!!!!!!!!!!!!!!!!!!!!!!!

[@MotorAgeMagazine]

Not my idea! The oldest reference I know of is some old Chrysler factory training that first taught this method. With the increase in the use of ECUs, the method was reborn and I first heard of it from the guys over at CarQuest Technical Institute. I'm just tryin' to spread the word! :-)

[@CraigSmith1]

Thanks for the video, I have a 2009 f150 that has a battery related problems. the battery was tested 6 months ago and they said it was fine. Will try method 3 if I can find a multimeter that I can borrow. I'm also aware that I do have a blown fuse as one of the AC power outlets doesn't work. Not sure if this should happen or not, but if I plug my phone and charger in, remove keys, the phone charger will have power for several hours. Needles to say the battery would be dead after 30 minutes.

[@davebell46]

Very imformative thankyou!

[@Robert-ts2ef]

Excellent but how does a diy guy get hold of the power distribution diagram.

[@XENONGAMER007]

on the digital meter do i use dcv or dca or other

[@MotorAgeMagazine]

Use the millivolt setting on your meter when using the fuse/voltage drop method. Amps if placing your meter in series with the negative cable.

[@fivefortyeye540i]

@ mortoragemagazine will you do a segment on can bus systems like what is it? How dose it work?? The way modules communicate on the bus.. Will there be anymore afterhours segments!??

[@williamvannostrandjr6948]

Well done.

[@quietbone]

Question, what car is at .41 sec into the video? Love the interior layout.

[@Robert-ts2ef]

That’s great for parasitic drains that are permanent but if it’s intermittent how do you do that?

[@orfeous]

Nice! i must test this method myself! Got a Volvo S40N 2006 with some kind of battery drain. This method seems to be better instead of clamping or attach probes in cable end and the other on the battery negative. etc.. but how can i know how long it will take for my car to go into "sleep mode" ?

[@MotorAgeMagazine]

Send me the fuse numbers of the three that show current flow when all is off and sleeping. Let's start from there, but give me some time to look over the schematics. I do have a magazine to get out! :-)

[@spierotti14]

thats a good idea, but I don't have an amp clamp. Ill have to try to find one. Any other ideas? Why do you suppose the amp draw increased so much when I disconnected the main light switch(just curious). Thank you for the responses I really appreciate that, its wonderful to have a little help sometimes.

[@johnroberts1708]

Brilliant! I knew about the multimeter, in series option, but your video has opened my eyes to other ways. I'm struggling to identify my parasitic drain but I think that may be because I have to disconnect the battery and then connect multimeter. Just wondering if the reason it hasnt shown up (after days of watching it in my garage!) is because I disconnected battery before putting the multimeter in series

[@MotorAgeMagazine]

Could be, especially if it's a control module that is causing the drain.

[@johnroberts1708]

Motor Age Magazine OK. Thanks. I will have another go (I quite like the idea of checking voltage across all fuses idea). Its proving very difficult to identify though, so I think I'll be fitting a Battery Brain or PowerTector in the meantime

[@spierotti14]

I have another question. Say I find a draw on the main power or ground wire for the lighted control module. How will I know there isn't something esle telling the module to stay awake via the can bus wires?

[@spierotti14]

I'm 100% positive there was nothing open. Verified a few diff ways the switches to trunk, hood, and glove are closed and function correctly. I even took out the light bulb. 2 of the fuses have one thing in common which is the lighed control module. I think something is keeping it on too. What do you think about when I disconnect the main light switch and amp goes up?

[@alieyesonme247]

The million-dollar question are ladies and gentlemen is simply this, what one thing call Brooke is causing these things to remain on it cause this draw

[@TheWhisky81]

hi great video, i have just started my course in hgv mechanical and electronic systems, on the trucks i work on they use 2 12 volt batterys to run a 24 volt system were as i know cars only have one battery for a 12 volt system, so when you put battery pack on then that would be like having 2 12 volt batterys making it a 24 volt system or are they connected differently? i am new to this, thanks john

[@stanleytolle416]

Yes you stuff is useful but what if it's an intermittent key-off draining. I have a friend who has a 2006 BMW 325i that is dead two to three times a month (all hours calls "Can you come and jump my car.). Altenator (twice) and battery have been replaced with both testing out good. Thing can go dead in less than 4 hours. Nothing appears to be staying on. Is the solution crushing?

[@MotorAgeMagazine]

As a good friend once said, "There is no such thing as an intermittent problem. We just have not recreated the conditions under which the problem occurs." Try to find out as much as you can about how the vehicle is being operated or stored when the problem occurs. One tech reported a case of unknown battery drain only to discover that the customer was leaving the smart key in range of the car at night. The two were constantly communicating! Tracing with a scope may also be helpful, using an amp clamp on either side of the battery. Good luck, and I hope this helps!

[@lesterl9654]

Thanks for posting this. I have a question about the jumper box used in the first test. I see that you connected its lead to the battery accordingly, but would like to know what settings were employed on the jumper box? Thanks.

[@MotorAgeMagazine]

No settings available on this unit. It's just a deep cycle battery housed in a plastic case.

[@James-fs4rn]

👍 thanks again!

[@luisgamez9941]

Thanx for your helpful video. You made it so easy to locate the power drop with the fuse check. But I have one question, what if you have to check a relay box?

[@bigmac8299]

Only way I know is to pull each one and see if theres a drop other than taking it off and testing the leads with the voltmeter

[@MotorAgeMagazine]

All circuits are fuse protected, even those controlled by relay. You'll need to first identify what fuse is indicating an active circuit and then review the power distribution schematic to identify what circuits the fuse is protecting. You can then use a low amp clamp to further isolate the problem by clamping around the power wires feeding those individual loads.

[@ScottEsser]

I'm trying to find out what's draining my '01 Forester's battery so bad that I've had to replace it twice; once after two years of sitting with minimal driving, then again about 6 months later with infrequent start-ups. I followed your third method and found only one draw, 0.35 mA on the cabin clock fuse. Is that a normal amount of draw when the clock isn't even showing the time and the key is off?

[@davetuttle9701]

Excellent!

[@nabbez5436]

thanks a lot for your time I like your chanel I learned a lot from it is have a Renault laguna 1.9 diesel it runs for few miles and stop completely it starts again after it get cold and the same again dies after few miles any suggestions please and thanks

[@MotorAgeMagazine]

Sounds like it's running out of fuel. I'm not familiar with the fuel delivery system but look for the volume of fuel being delivered - not just the pressure.

[@donvito204]

I've got an 03 grand marquis and when I do a parasitic test it shows 0.03 amps but my battery dies in 2 days if I don't disconnect the negative cable

[@billsmith2212]

I am currently working on a 2002 Taurus . The battery which is only 19 months old , goes down after a few days . I fully charged it and disconnected it . It fails under a load test after sitting , disconnected , after a week .The car , after a parasitic drain test was at 20 milliamps - well within specs . It took an hour or more to power down . You can do a ripple voltage test on the alternator . That will tell you if the diodes are bad and allowing current to drain when the system is not running . The alternator on the 3.0L , DOHC Taurus is HORRIBLY burried , so that test is almost impossible with a DVOM . I have a Electronic Specialties 725 Battery Tester and it will run the test at the battery . Many high end testers have this . I would also fully check the charging system . Make sure no add on items such as alarms , radios , etc. are powered on . Sometimes a rear wiper is stuck on and keeps trying to " PARK " itself , even cycling every few seconds or longer .

[@MotorAgeMagazine]

OK, give me some time to review all the info you've given me. I WILL get back to you as soon as I can.

[@greygoosemafia]

I have a question. on older vehicles such as 99 dodge ram. should you use the hot wire or neg wire? does it really matter?

[@billsmith2212]

Pete : On my jump pack , there is an adapter to charge it in the cigarette lighter . Wouldn't this keep the system powered if plugged in ? I believe it would also work as a memory saver . Thanks for your information .

[@MotorAgeMagazine]

Keeping memory alive by plugging into the cigarette lighter (now the Power Outlet) used to work - but no longer and not for some time.

[@spierotti14]

Ok, after the meter is hooked up in series I have about 400ma then I pull the fuse 2.31 and jumps up to 10amps. Just like you pull fuses to see if the amp drops. I can't get the mv for you but I can't tell you 2.31 is the highest 2.30 is 2nd and 2.19 is last. I think it was something like 2.31 .125mv, 2.30 100mv, 2.19 .020mv

[@orfeous]

Went out to my car today and did some measurements! Measured mV over my fuses like you did.. got 0.2mV over everyone. But didnt remember if i forgot to measure with battery cables connected to battery or not.. hmm what will happen if i forgot to connect negative cable to negative battery? is it possible to get my 0.2mV reading then?

[@interstategar]

I have a '08 Ford van and after testing, the A?C clutch circuit is draining the battery with the key off. Is the relay bad? I already replaced the compressor with a new one that had a new clutch that came with it. How can this circuit be draining the battery with the key off?

[@vicky-nc3to]

Great video.......If battery is to be removed/ replaced, I always have to go for steering angle calibration in Porsche cars, so if I connect jumper as according to you, do I need to do the steering angle calibration or not ?

[@MotorAgeMagazine]

As long as there is never a loss of power to the modules, I would think you would be fine. Just be sure that whatever procedure you use will indeed supply power to that module.

[@lloyd-qt1mg]

Hey Pete.... what about intermittent parasitic voltage draw , like wipers that turn on intermittently? You could test the fuse when the signal is off and completely miss the 'parasitic draw' from that component. Method No.1 ... using the Max/Min facility on the DVOM ... will indicate intermittent voltage draw, from all components, won't it?

[@MotorAgeMagazine]

I made another video on this subject, and show a method for catching the intermittent. You're right - you can't track the draw source down unless it's active, so use a separate amp probe to monitor the draw and only test across the fuses when you see the draw occurring.

[@lloyd-qt1mg]

@@MotorAgeMagazine Thanks Pete for your prompt reply, Ill check that video Best regards.

[@johnp5639]

Great video! Please give me the manufacturer / model of your multimeter. I need to buy another one that has more specific functions for electrical DC work. Thanks.

[@MotorAgeMagazine]

This is an old UEI unit that finally died on me after more years than I care to admit to. That model is no longer available but there are plenty out there, in a variety of price points, that will do the job just as well. Check out my friends at www.aeswave.com. They can steer you into the right one for you.

[@spierotti14]

How can I without blowing dmm fuses? What would you say turns on all modules? When I hook my dmm up with out usind the tool of the neg post, everything connected I start about 2 amps, 10 sec later .8 amps one min later .4 amp problem that stays