This Will Protect You From Replacing Modules That Aren’t Actually Bad!

[@chicanobluesaz4191]

You are hands down the most precise and well thought out technician on youtube. I did this type of work for 25 years and was always helping others learn this stuff and fixing problems like this for them. I commend you for your amazing videos. They are greatly needed in todays auto industry as there is a significant lack of knowledge out there.

[@leftyspinn]

Sherwood is good but wait till you watch bernie thompson from automotive test solutions

[@chicanobluesaz4191]

@@leftyspinn that guy is amazing as well.

[@EvzenKovar-i5p]

The way Sherwood explains things works perfect for my lizard brain. I have learned so much from him.

[@alfee9411]

These have to be done on every car that has strange anomalies electronically. Try cleaning grounds (all b to b) and replacing the negative cable assembly with an amp sensor, to eliminate 15 fault codes, no modules were bad. Yes it takes time but we live in the rust belt and no modules bad, priceless feeling.

[@charleskuss8538]

Absolutely awesome video. Where can I buy that simple light bulb 2 Amp Load test tool?

[@mordaccadrom250]

Process.... Technique.... Practicality... Education... and Entertainment. Who could ask for anything more? Nice work! Thanks for the video and efforts!

[@dporrasxtremeLS3]

YES!!!

[@marriagepartnersministry5942]

In airconditioning HVAC work I frequently find a pitted contactor that will show 120volts to ground but the moment you put a load on it the pitted contacts resists the voltage and I get a reading of around 80volts or something less than line voltage. Testing under a load is the only real way to test. Also, in HVAC the hot side is what is switched and NEVER the neutral. So alot of guys test the hot side of a component and assume the neutral is intact but this can give a false indication that the component or the neutral line is good. For example: if you test the 24 ac volt contactor coil by probing the hot and neutral terminals, if the neutral line is broken and the hot is good then the meter will show 0 volts and a person is fooled into thinking that the control voltage of 24 volts isnt getting to the contactor. The proper way to test is to prob hot terminal to neutral and then to ground. If the hot terminal and neutral terminal shows 0 volts but the hot terminal and the other prob to ground shows 24 volts then you know you have a bad neutral line.

[@robertkincaid9122]

Retired master electrician restore cars for hobby. Best video for electrical trouble shooting. Great video thank you

[@robertgreen4050]

Anyone that wants to learn the basics should pay attention to these videos you do like this especially with all the electronics and computers and modules in vehicles today I don't care how old you are or what you think you know excellent job Sherwood enjoyed it

[@davidl766]

You just earned my respect! I’m a mechanic with 35 years experience, you won’t believe how many out there don’t know this very basic, but complicated at the same time, knowledge. Another fine example of Ohms law! Everyone should have E=IxR, tattooed on their brain.

[@michaelmiller7601]

I really appreciate you taking the time to educate the next round of technicians

[@terriecotham1567]

well said

[@markm0000]

I spent an entire Saturday in the shop on my time with a module that didn’t work right. I checked and swapped everything under the sun to try and figure it out. It ended up being the connector to the solenoid was pulled on by the previous snapped belt just enough to no longer make a connection. As soon as I turned off my multimeter and used a test light the answer was obvious. The wire was visibly intact and the connector had no corrosion. What a lesson to learn.

[@thisisyourcaptainspeaking2259]

Goes to show, the root cause is always the last thing you check.

[@stuckinmygarage6220]

😅​@@thisisyourcaptainspeaking2259

[@chuckbeam7898]

I’m a DIY mechanic and a lot of this is over my head but hopefully I can glean info I can use down the road. Thank you

[@adamc8409]

Simplest way to explain it is youre looking for voltage drop from a bad ground. Grounds are typically what leads to haywire electrical problems.

[@kellyblack4897]

@@adamc8409or short to ground and this method will detect both!!

[@TheDesertRat31]

Testing for a voltage drop on the ground side will show a bad connection, either no connection (test light won't illuminate) or a bad connection from corrosion or something else. There should be no voltage on the ground side. If you see voltage (which appears because of the current drawn by the test bulb. Think of Ohm's law) on the ground side, whatever the bad connection is, it is creating a resistance. Remember V=IxR. The I is the amps pulled by the test bulb. If R is zero, then V will be zero. If there is a resistance greater than 0 , then you will see a voltage. He tested both sides of the circuit (power and ground) because there are 2 physical pathways (wires) that could have problems somewhere if a component is not operating correctly (or at all). The negative voltage on the meter during the ground side test just indicates the current is flowing the opposite way (an incandescent bulb doesn't care the direction of the current. An LED or something does, so they wont work as a test light). Think of the positive vs negative voltage as simply an absolute value. And like he said. Sometimes, there will be small voltage drops on circuits going through a switch. The switch will draw a very small amount of power usually. The wiring diagrams should tell you what the reading should be (usually a range) so if something reads too much or too little, that probably means there's a problem.

[@etiennebisset5642]

I salute you Sir. Thank you so much for these videos. May your tribe increases more.

[@marktoken6052]

I don't work on cars like I once did but I still found your video informative. I just subscribed. Kudos!

[@oddmanout7755]

Top shelf education level!

[@sollykhan2385]

The best tutorial on the power and grounds, with a no-nonsense approach, an amazing hard-won experience that saves the day, Thank you so much for your kind effort to produce great content, please post more, ohh who is that small Lad,,, an apprentice..they start early these days 🙂

[@redskinsfan3197]

SIR YOU ARE A GREAT TEACHER!!!!!! THANK YOU!!!!!

[@garyalford9394]

Wish I could be young again and have a teacher like you! We had no auto classes in our school, but it was also alot simpler in those days. Please keep up the good work I know alot of what you do is not easy.

[@philkuusisto1558]

Great help for electrical problems, which happen too often and not knowing where to start. Thank you.

[@RudyGarbely3]

Another great video Sherwood! I have been a Honda tech for over 41 years and another thing you should check is the pin fit at the connectors at the PCM. Have seen a few in the last few years with a loose fit causing an intermittent problem. Honda has sent us a pin fit tool kit in order to do so. If the pin fit is loose Honda has us replacing the wire harness as there is no way to repair/replace these tiny terminals. Great videos, I have learned some new techniques/lessons from watching them!! Thanks again!

[@swampyfox8688]

Thanks Royalty!! Congrats on 120K!!!

[@IronMan-ml5yi]

I like you style. No bs. Just facts. Bravo. I appreciate it thank you. - new subsciber

[@jgeorges3061]

AWESOME approach and thought process and indeed this will show you that u did not miss any thing else in calling the modual thanks for sharing.

[@Gruin]

Sherwood shows one the Light in the Forest. "The Finest Kind" Thank you

[@emylrmm]

master mechanics today have be electronics technologist too. It's a huge skillset.

[@philh9238]

Yea we sure aren’t paid enough

[@chicanobluesaz4191]

Yep! And shops and dealers don't want to pay you for your skillets that you've invested a large amount of your life and money on obtaining them. That's why I left after 25 years. And I specialized in electronics/electrical including EVs and hybrids. The industry needs to change.

[@philh9238]

What field you in now? When I was in shops I’d look at ignition waveforms injectors etc. same line from the shop owner it’s a waste of time sell something. Then he’d get pissed when I asked okay what do we need to sell to fix it without guessing

[@chicanobluesaz4191]

@philh9238 ya waveforms are beyond a doubt an end all discussion about what's failed. But what's quicker is having known good spares lol.

[@chicanobluesaz4191]

@philh9238 I'm working at Intel now as an automation equipment technician. I love it and I have 4 days off 1 week and 3 the next and overall im taking hone more money at the end of the day. Plus the Benefits packages and time off we get are 2nd to none. I regret being an auto tech as the benefits in the auto industry can't compare whatsoever. It's disgusting and shameful.....

[@Eddy-rq7ge]

Excellent job Sherwood. I hope a lot of people got some good info from this today.

[@Davidnichols-p7w]

You are an excellent teacher. I have learned a lot watching your videos, thank you for sharing them.

[@victoryfirst2878]

I am amazed the hand held power module does not have a 1 amp load check RAS. Nice video and one more thing, its the little things that make the big things happen !!

[@Tacticoolpapi]

Didnt know about the solid line vs dashed line difference. Thank you for the knowledge.

[@FIRSTWORLDSTATUSBY]

man !!!... you explain it all so well !!! - thanks for your explanation... most valuable

[@kellyblack4897]

The 2 amp bulb is old school. I use this for shorts at the time. Good show man!!

[@sollykhan2385]

2 Watt ? 🤔

[@seanshute9284]

​@sollykhan2385 pretty sure he means an incandescent bulb used for testing that draws 2 amps

[@greggc8088]

Loving this video on basic module power/ground check. Also loved the one a few days back on power probe safety. These are two I'll share with my techs for their training. Thanks

[@wingman8447]

Another great real world troubleshooting lesson. Thanks

[@spirokattan3655]

Great tutorial! Thank you Sherwood.

[@ThunderbirdRocket]

Awesome lesson ! Excellent videography !!

[@ysitrim88]

Awesome bud thanks for the great tip. I will start doing this if im in doubt about a bad module.

[@josephlieberman3027]

Thank you for the Steadfast determination to present the intuitively profesional approach and methods often disregarded and leading to bad practices. It is profesional and good teachers that initiate the lasting roots for good practice of future professionals.

[@hawkeye7558]

Clearly explained! Great video!

[@tylerwilliams3868]

this video answered the question i needed! i wanted to rig up my own load tester with a bulb but have a small voltage reader hooked up with it aswell!

[@willmcgo8288]

Good lesson. Year ago, dealer didn't do a load test before replacing the ECM on my year old Nissan. Car wasn't running, still didn't run after the new ECM. Ended up being a ground connection that they had not put together properly (in a hard to get to spot) on a recall repair they had performed a few months earlier. Had they noticed the ground to battery negative terminal was not a near zero value earlier, it might have gave them the clue they needed. Might have also helped if they considered what work they had performed recently. Thank fully it was all under warranty, so it didn't cost me money, just time in the shop.

[@georgemccool5936]

Always just looking for the reference absolute value

[@KeggyUran]

Great video. At the dealership, I use a sealed beam headlamp for load tests. Draws about 3 amps. I also put a cylindrical dome lamp bulb in my test light to increase the current draw and brightness. Do not use a led test light.

[@pontiacsrule8761]

I really appreciate it. I'm not a shop. i can't eat a module at these prices. Great video & thanks for making this.

[@anthonysova7117]

Nice video Why not put the meter in millivolts to show the actual drop?

[@barrymiskell3760]

you are right about the grounds being most of the issues. that has been what i have found and the other has been bad batteries. in my shop i cant get it through other techs heads that vehicles now are rolling computers and 1st thing of making sure battery is good is critical. Thanks for your education to other techs that are not strong in electrical repair. Most shops in my area send this type of work out.

[@curtomaru8077]

Thanks for the wiring diagram tip

[@Sid9397]

very good training video!!! looking forward to the next one :)

[@sheerwillsurvival2064]

Excellent. These are great videos

[@Jeff-bz5fg]

Excellent job in explaining exactly what to test and why it may be bad!

[@thomasherring6640]

Great video, well explained, clean and concise. This kind of content is great for the diy folks out here!

[@EverettBenjamin]

I also use a similar scenario when performing a continuity check. Many times a check with just a meter will show good as it only takes one single strand to pass a continuity check with a meter. But if pulling a load through the wire you can find corruption as one strand isn’t enough to pass the current through for the load.

[@onlywenilaugh6589]

Many DIYers can't get hands on the wiring diagram unfortunately so we have to try to figure it out. I wish they would make all wiring diagrams public domain and available free on their websites.

[@robfranke1]

Great video. Must be able to Diagnose a problem! Duplicate a problem! Understand system functions. THE DIFFERENCE BETWEEN A PARTS CHANGER And a parts changer...more great tools to save time. Have rigged up stuff like that in th past..having great diagrams is key!

[@lobdsk]

Thanks again for helping the world I don’t know what any of this is. But thank you man

[@gregoryosborn2228]

Thank you from Arkansas! Love your videos and teaching!

[@LynxStarAuto]

Good stuff boss. It gets more fun when you want to load test higher voltage systems like the 48v systems found on the newer Euro cars.

[@Tom-7777]

I had a 6 year old F150 brought to me after others threw a 4x4 module at it and a servo motor, I tracked the wires the same way and found a main wire to the transfer case module that had corroded thru in the middle of a harness wrapped up with 20 other wires that was undisturbed under the hood, it was probably cut in the manufacturing process, lesson is never underestimate wiring issues before throwing parts at a problem.

[@doug2202]

Great video

[@danieljurgill1681]

1. If you know the normal load for the circuit in question, use an appropriate incandescent bulb that uses the same amps. For instance on old batch fired system with 4 injectors on a driver, the circuit might draw over 3 amps. Then might need a larger bulb, like a headlight. 2. You must use the location of the battery at the exact center of the post or center terminal bolt. If you connect the alligator clip to a post clamp bolt ,you could miss a large voltage drop at the terminal clamp itself. There can also be a corrosion problem at a junction block ,where the battery cable goes to. 3. Before condemning an electronic module you must also check for corrosion and pin fitment on both the harness side of each connector and in the module side. Good job on the video !

[@konstantin-big]

That's right First we look=test at the voltage drop across the battery terminals

[@emylrmm]

great advice!

[@michaelsimon7414]

I will make a duplicate Amp draw light /volt meter tester soon!!

[@sollykhan2385]

@@michaelsimon7414 please make 2 and send me 1 🙂

[@spiculum1836]

Excellent way to check integrity of power and ground wires. Quick way to get rid of the negative symbol on the MM is to swap the MM terminals at the multi-meter side. Good way to demo a loaded voltage test and no load voltage test is to put a 1 ohm 10w resistor in series. With no load, the MM will show battery voltage (12v) between ground and 1 ohm resistor (other end of resistor touches + terminal). When you do a load test with a 12w bulb (drawing 1 amp) the voltage across the bulb will be 11 volts instead of 12v. The 1 ohm resistor is simulating the bad connection to ground or power.

[@sollykhan2385]

Thanks for the excellent input, Do you do electronics ? i was always interested in electronics from an early age, if only people would study a bit and practice a lot more, then most of the impending issues on vehicles can be easily solved.please post more great idea's, knowledge is a wonderful journey that never ceases.🙂

[@bobbrown9277]

You are the man.thank you for all of your videos. They are awesome

[@joedantuono3467]

Adding a multimeter to power/ground testing adds a nice touch of precision to the simple old "how bright is the test light?"

[@stevetaylor2445]

I was taught to do the voltage drop test the was you describe the starter voltage drop test in parallel to see the voltage that is not able to flow through the conductor to the load The next test you show is wired in series and is a completely different test with different results

[@terriecotham1567]

Well done, cars have become like computers and more than once the new meters will read a voltage when there's no current, or show a ground when its bad, nothing like putting a good load on a circuit and seeing what happens. Well done i even pick up a tip I never caught before, or notice thanks for tacking the time to post and helping new or old techs learn a thing or two See you possible have a new tech learning from a master tech as well

[@steverogers7545]

If you don’t like doing math you can connect the meter - to - or + to +, and when you load the circuit, the meter will show the voltage dropped. Either way, great testing methods, wish more techs were doing this!

[@cdsfleetrepairs]

Help please explain the difference between this setup and using the load pro, I see ton of videos on the load pro and I see a ton of videos using the bulb method. Have purchased products from Jar head diagnostics but pass on the bulb tools, not to say there not good but never had anyone explain in detail setup and operation like this video, thank you for your time spending on producing your content. definitely will be revisiting the bulb technic

[@paulnewton943]

Excellent process of elimination. My question is if you dont have a manual what site can you download from? Thanks

[@richardlederer-v5d]

I have a question about CAN communication network wires. Is it possible to do a voltage drop test across the network areas like p-can, c-can, etc?or is voltage too small to detect a voltage. I hope this isn’t a stupid question to ask

[@aarontyrrell2931]

Great video, thanks for taking the time!!

[@FullFaithRepair]

Great video, valuable info here...thanks for sharing!

[@stevemac8436]

As you easily remember, once upon a time, you couldn't just touch the leads of a volt meter up and the meter tell you it's backwards. It would stop working. You would get to open it up and repair it. 😅😂 Repair? What is repair? Thanks for the memories of the times I/we thought we had it ruff! As I watch a mower repair channel guy say, "this ain't the space shuttle, it's a mower!" When I work on cars now, my new saying is, "this ain't a mower, it's a 100 miles of wires, connectors, switches, module's and designed nightmares on purpose!" Grounds should be the 1st place to look for problems. Thanks for the details.

[@quercusrubra777]

Great instruction. I enjoy your videos. Thank you.

[@danieljohnson8437]

Load Boxes... Excellent

[@dtnel]

Sherwood!!!! This is my biggest problem especially when there’s 8 wires going to a switch and I see that wire go another place then another then another I get easily confused. Also same thing when there’s 8 wires going to 8 different modules in identifying which do what in relation to turning things on.

[@COBRO98]

You have to consult wiring diagrams, otherwise you're just guessing. There are over 3,000 wires on a modern vehicle, about 150lbs worth. If you don't understand how something works, you can't test it, if you can't test it then you can't fix it without guessing.

[@RaymondIlano]

Excellent video! I'm def ordering that bulb load tester tool! Which bulb did you use to pull 2A? Thanks!

[@pablof.torres-kandelers1906]

You the best thank God for all..

[@ryan.mullen]

Shout out to Check Engine Chuck 👍👍👍

[@odishoodisho4904]

Great as always

[@luisdaluz4686]

Awesome video guys

[@rolop847]

👍 nice and easy to understand, thanks.

[@wisdomsquare28]

Much gratitude!

[@thisisyourcaptainspeaking2259]

2A would be a 25W, 12(13)V incandesent bulb. A 4A load would be a 50W bulb.

[@chrisbrodbeck1961]

Don't have that software yet,,, slowly moving towards that!

[@jeffalvich9434]

Well said & Presented!

[@Dcalvert92]

Apply these same tests to the CAN network. If a module has the proper powers, grounds & CAN bus connectivity / resistance but still will not perform, the module is faulty.

[@sollykhan2385]

yes accurate assessment, i had a Mercedes W205 that was a total nightmare, in the shop for over 5 Months, no crank no start, and endless Fault codes that would not clear, so many overlapping Can networks that had failed due to a few faulty modules.

[@christianlopez6940]

Couldnt you use the break out box for this? Im still learning on being a tech.

[@TheMessiah91]

Doing this to a 1996 Chevy 5.7 that blows up ECM fuse 20amps when running after a few minutes but stalling it does not blow up. Thas fuse is Postive and feeds a multiple sensors studying this video to find the issue. Im pretty sure its a intermittent short and load testing is going to show me where the issue is. Thanks!

[@redneckpotatoe]

Remove fuse, connect multimeter lead to side of fuse supplying the load, connect other lead to ground, set meter to Ohms, then wiggle wires and such and see if you can find the short.. helps if your meter beeps when there is continuity

[@codo7]

Good job.

[@rogerpatton-zr7qd]

I feel that you can perform that test. But if you don’t do a key on a crank. You’re not sure the grounds or the pod can carry a load. An I thought that it would be a better test to test on the mili volt scale.

[@timothyschraf236]

Thanks for the advice 👀❗️👍😊

[@yeayeasautoadventures]

I always used a 9005 or 6 on a disconnected circuit

[@sollykhan2385]

please expand on the comment 9005 ? 🤔

[@yeayeasautoadventures]

@@sollykhan2385 9005 headlamp/bulb

[@rickmurray7123]

@@sollykhan2385 9005 & 9006 are standard headlight bulbs.

[@Pares7594]

Great video . Keep it up 👍

[@crasher88]

you forgot to mention that sometimes a PCM will control a relay and once that relay is energized addition power circuits that go to the PCM those need to be tested as well you will either have to by pass the relay manually(if possible) or active the coil for the relay with a test light.

[@sollykhan2385]

Yes Spot on, thanks for that tip.

[@lynncummins6903]

Great video and how to.....

[@aerotech1bob]

Great information, thanks

[@MrPanchito2233]

Can you do this test for components that have a load already in the circuit for example an H02 heater circuit that uses a ground to the ecm.

[@COBRO98]

Absolutely you can. A 2-amp light bulb perfectly replicates the sensor. Just simply unplug the connector and carefully probe your test light.

[@James-fs4rn]

👍🏻 great content! Thanks for sharing

[@michaelmiller7601]

Nice load testing would we not check bus voltage before condemning module

[@charleskeenom9481]

Thank you so much I just learned a lot thank you

[@abdulali46]

Great information

[@marcisaacs9407]

Off topic but in view of your expertise I have to ask about 2004 grand marquis LCM and it’s unreliable performance. I know about the recall and although never had a problem, went for it a few years back, just now fall 2024 I think it’s gone goofy and I thought to replace the relays because of intermittent behavior. Is there a relay that is perhaps rated a bit stronger or more reliable than stock? Respectfully 🙏

[@raymondferguson1935]

What do you think of the load pro for this type of test when testing the circuit