Motor Age How2 #13 - Performance Test The Starter Circuit When The Starter Is Bad

Here's a tip I learned from NAPA's Tom Rayk at the TST Big Event held March 25th. It's a way to test the integrity of the battery cables/ground path when the starter has failed and is not available as the test load. And you may have all that you need to perform this test already in your shop!
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[@nickayivor8432]

Good Morning Pete Meier motor age Take care and have a great day 👍 Great tutorial thank you 👍 Nick Ayivor from London England UK 🇬🇧

[@mike-yp1uk]

Great idea taking the diagnosis to the finish. Tell a customer he needs a starter and call him back with an estimated battery cable doesn't make us look to good. Im starting to watch your videos more and more because you explain things really well. Thanks for the good advise

[@MotorAgeMagazine]

Thank you!

[@RobertBee-fs8hv]

He explains well to those who understand the procedure well but for those who don't understand the procedure well, the explanation wasn't well explained. The camera was lock on to the narrator and so there was little demonstration of where the meter was attached and where the load tester was attached And what was the conclusion of the test . A one point 6 voltage drop across the positive battery to starter cable . Does that mean that cable is no good?

[@juliangalindez2951]

Picked up a few techniques last week at TST, including this one. Great demo Pete!

[@briansilva9120]

Great video, thank you Pete. I learn something there today 😊

[@samr.m.7709]

Pete, thank you for sharing. Very good technique.

[@josephtucci3666]

That was a great vid. And a great extra step that may keep you out of a jam Keep it up!

[@kevincampbell8298]

A god friend of mine teaches for Napa and others. Always great tips! I have used motors to test but the battery tester is a great load! :-)

[@DylanRabier]

Nice video Pete. Thanks for sharing this test. I still have the analog one... 😔😉

[@motorcyclesandridingfree2899]

That's excellent much easier making one phone call than two to sell the needed repairs

[@MotorAgeMagazine]

You bet - especially with the work entailed on many new vehicles when a cable has to be replaced.

[@James-fs4rn]

👍 thanks for sharing

[@authordavidlwallace1499]

Wow. Can you also do that with the alternator?

[@SouthMainAuto]

Hey Pete! Good seeing you at TST. Thanks for sharing this demonstration. Definitely a handy test if the original load is junk. Do you think if the starter was in place and you could get the load tester in there on the battery cable with out arching the best place to put the ground clamp would be on the starter case and not the engine block? Curious your thoughts on that. Take care --Eric O.

[@MotorAgeMagazine]

South Main Auto Repair Ground is on the starter case...couldn't access the cable while it was connected.

[@philh9238]

you could always use the magic cucumber with the magic button....

[@mph5896]

That test will be great for all the Caravans and Civics you have had in lately

[@MotorAgeMagazine]

I should add - for the benefit of everyone reading - that Eric O. is absolutely on target. By attaching the ground lead from the load tester to the starter case, we are insuring we are testing the entire ground path. Thanks for pointing that out, Eric! BTW - Check out Eric's channel. He has some great stuff of his own!

[@SouthMainAuto]

Thanks Pete I appreciate that! That was the main reason I asked that actually. I recently checked out a no crank on an N14 Cummins after a fresh rebuild at a local shop. The problem was they had so much paint on the engine there was 12 volts of voltage drop to the starter case. However the engine block had a perfect ground. We often tend to assume if the block is grounded so is the starter. Thanks Again --Eric O. Oh and the fix for that truck BTW was to remove starter, remove paint on mating surface and reinstall ;) problem solved.

[@vincebauer4777]

I use my scope with everything hooked up 2 channels cracking test or my power prob 4 feed test

[@NewLevelAuto]

Pete did you hear him also mention testing an alternator circuit this way in the TST class? I'm quite sure I heard it myself

[@MotorAgeMagazine]

Not that I recall - but if Tom did, I'm sure it would be as a side and would include mention of applying an appropriate load to the cable. I think that was his whole point - you can't adequately test a cable designed for a high amp load with a headlight.

[@billyr9840]

Nice !

[@oldsilkhat7893]

Pete, would a good start for a circuit when measuring low amps to reverse the math on the fuse you pulled. Say if you removed a 10amp fuse for your fuse buddy, then base your scopes setting close to 1ma?

[@MotorAgeMagazine]

Not sure what you're asking. Let's start with the problem you're trying to solve...

[@ronaldamodeo4567]

Pete, first how do you like the power probe multimeter? I have one and really happy with its performance especially bang for the buck. Second its a nice piece and I still have and use my toaster. I have used that method before and it works great but it has some flaws that I would like to share, for example when you disconnect the battery on a Honda you could lock out the radio (got the code), Nissan you can wipe out the window memory (can be relearned) and you will wipe out the drive cycles on all vehicles. I have seen this in the past and some customers are understanding and some are not and the not so happy one's are the one's that get towed in and are usually overdue for inspection. Just wanted to throw that out there..

[@MotorAgeMagazine]

I just recently got the PowerProbe DMM and so far so good. It's hybrid rated, has 10 megaohm impedance and an easy to read screen. And the price was reasonable.I I appreciate your comments regarding losing memory when disconnecting the battery but if the customer is told ahead of time that will happen, it shouldn't be an issue. Better yet, write down the presets if at all possible and restore them when you're done. Thanks for the comments!

[@ronaldamodeo4567]

I mentioned it battery disconnect because sometimes I have seen that oh s**t moment and then the customer gets the call. I agree on the easy to read screen for us older guys...

[@richardmcwhirter9396]

great video Pete thanks,Is there a test to see if the starter is lazy and drawing too much current?thanks again good work

[@MotorAgeMagazine]

A starter that is dragging or "lazy" will generally draw more current than a good starter, and spin the engine more slowly. You can perform a relative compression test with your scope (kzbin.info/www/bejne/aHzbqYSnqL1gpdE). That will allow you to measure engine rpm and starter current draw. If draw is high, verify the integrity of the circuit paths (like we did today) to isolate the cause to the cables of a faulty starter. Engine cranking speed is critical in most diesels where cranking speeds less than 400 rpm or so can cause a "no start" complaint. Good question!

[@richardmcwhirter9396]

Motor Age ,thanks Pete I'll try a few known good starters against lazy ones to see the difference on the relative compression test,thanks for helping

[@MotorAgeMagazine]

To clarify for you, when you capture the relative compression waveform you can see what the average cranking demand was. We all learned that early in our training, right? :-) You can also place your cursors on the peaks (4 for a four-banger, 6 for a six cylinder, 8 for a V8) and calculate rpm. Of course, if it's really bad you'll hear it. Then it's just a matter of determining if it's caused by a voltage drop issue, an engine or accessory mechanical fault, or the starter itself.

[@ravineseder3133]

How many amps do you set the load bank for? Different starters, different amps. Or is anything in ballpark ok just for testing cables, like 50A. Also, before going to the trouble of load testing, which is cool btw, I would check the connections and if they were corroded or loose but cables seemed ok, I would assume cables were fine and just clean up the connections.

[@MotorAgeMagazine]

I like the load test of the cables because the corrosion can extend into the cable itself. Sure, clean and tighten but still check just in case. As for current amount, you need enough to stress the cables similar to what the starter will when cranking.

[@jdere31760]

pete, could we use the "load pro leads" by Dan Sullivan to do this test? I believe that there is a resistor in the napa tool and load pro leads but not sure of compatibility.

[@MotorAgeMagazine]

Good question! I don't know if the built-in resistor in the LoadPro (or equivalent tools) would be sufficient to stress the cables close to what they would experience under normal use. Try it and let us know what you learn!

[@jdere31760]

@@MotorAgeMagazine Okay Pete, I have a Jaguar XJS that I have hard starting when car is already warm. The starter cables are pretty hard to get to but I will let you know!

[@MotorAgeMagazine]

@@jdere31760 First, define hard starting...does it spin slowly or crank at a normal speed? And you can perform a normal voltage drop test on the cables since your starter IS working. This test is for verifying cable integrity when a starter has failed, prior to replacement. Don't forget to make sure the battery is ok! Hope this helps.

[@jdere31760]

@@MotorAgeMagazinePete, the starter spins slowly after driving for half hour, then shutting off the engine and restart within 10 minutes. Regarding voltage drop, the battery cabling set up for the 1989 XJS is not typical. Battery is in the rear of the car. The 31 year old heavy gauge positive cable splits at least three times before going to the starter. I tested for voltage drop up to the last terminal before the last positive cable heads to the starter. This last portion of positive cable going to the starter is more difficult but I hope to get to it soon.

[@jdere31760]

I thought a normal voltage drop test would be one lead of multimeter connected to positive battery post and the other lead goes to the positive terminal connected to the starter. I would have a couple hours work trying to disconnect exhaust down pipe from exhaust header then I would be able to see and connect to the positive terminal of the starter,

[@verajavi12]

good tip,only disagreement is charging customer for extra test where I come from a tech needs to do test for free just to cover his butt,customers dont want to hear details on extra test they just want to pay as cheap as possible.in this trade the best tech is a tech that applies attorney skills first and then he works,veterans know what I'm talking about.

[@robertgonzalez6012]

omg the typing sound is so annoying!!!! awsome class tho!!!