Voltage Drop Testing a Starter Motor (Quick Tips)

[@TheCrazy243]

Thank you for making me a great technician not a part changer. My birthday was two days ago and worked couple cars on that day. One of them was kicking my butt! 92 Volvo 940, crank no start. I never work on volvo so I took a gut to look at it. Did all basic. (Air, fuel, spark,timing, compression). Fuel injectors failed so I went to that path. Still couldn’t figure it. I went home and did homework. I went back. Indeed , wires on relays (control injectors) came loose. I cleaned it and put in back. Still wouldn’t start. Owner mentioned it that she messed the wires around. I was thinking if I put wires in wrong slot. I looked at schematic. There pin number and I followed, put wires in correct slot. Car starts and run. Best feeling ever. Took like 5 -7 hours back to back.She called couple mechanics and they kept guessing and was coming with some parts . They were gonna put fuel pump in it 🤣🤦🏻‍♀️. I literally saved her from dummy part changers and towing fees.. I almost gave up but didn’t. Thank you for all you do. You are my mentor.

[@nicknesler]

Good job, dude

[@Ken-1]

After watching these types of scenarios from you so many times, it felt so good to run into my first bad block ground in the field. Found that thing in 5 minutes tops. Truck had been down for months with many new parts, new keys, all types of junk. Owner thought I was some type of sorcerer after that one LOL

[@ScannerDanner]

Awesome! Thanks for sharing

[@CrystalGeyser69]

The block receiving voltage is a good ground connection or bad?

[@Ken-1]

@@CrystalGeyser69 bad. Block should always read 0V or very close to it. If the block has battery voltage with the key on (not cranking), it is missing a crucial ground path.

[@CrystalGeyser69]

@@Ken-1 okay thank you that helps a lot that is exactly what my multimeter is reading. I touch the red to the positive on my battery and the negative anywhere on the engine block and it’s reading 12.5v

[@Ken-1]

definitely a ground problem. If you don't see anything obvious while visually inspecting, I would recommend grabbing diagrams from Mitchell DIY for your specific vehicle. $20 for 30 days all repair information and diagrams for 1 vehicle. I've spent hours tracking weird issues with no success only to pinpoint it in minutes after consulting a diagram/flowchart. Saves lots of time (and frustration) Good luck! @@CrystalGeyser69

[@brianmason8400]

You, Eric O from SMA, Ivan, and Keith have all been my role models since God knows when. You've made me a MUCH better diagnostician. I actually find higher paying employment by selling my diag skills. I watched the other video you linked me to as well...... awesome stuff bud!!!!! Thank you 😊

[@DJ-tn7vj]

Yup for real

[@NewLevelAuto]

Thank you Brian!

[@AKChryslertech]

Yes! Danner, Eric, Keith, and Ivan are the dream team!

[@ivaneu1]

I agree and add one guy, you should looking for DiagnoseDan on KZbin,this guy have a good technician on European cars. Thank you Danner for this good video shared with us.

[@meorge9359]

Have to agree with this ! I’m the youngest guy in my shop and am making more then most the other guys since they don’t understand basic electrical

[@markraz28]

Wonder how many people would change the starter and never know the real problem? Great vid as always

[@jakawild6496]

Tell you what, no matter how simplistic your videos may be sometimes, I still find them valuable. I forget little pieces of information sometimes. You and SMA are my go-to for a quick refresher. Yall doing great work.

[@spelunkerd]

Brilliant video, as always. In a sloppy shop they would have sold the starter motor and fixed the problem, never knowing the error. You won't often be wrong if you blindly follow the three step recipe of of B+ always on, signal on with key, ground always off. In a busy shop your test takes less than a minute, maybe five minutes to set up an extension if you don't have a friend to turn the key. The great thing about a cookbook recipe is the way you don't need to be thinking too hard, just do the test and you'll be far ahead of many pros. That said, I've been scratching my head about the chance of a falsely reassuring ground test. With my favorite Scannerdanner triple test, there is no control to the ground test, as you poke at the oxidized side of the housing, we assume good contact. Also, a normal test light needs about 3V to even glow faintly, which is way higher than acceptable voltage drop on the ground. So here's a possible more trustworthy solution that takes one minute longer. Before starting you attach a multimeter to a good ground on the engine, quickly verify it is 12V from the pos battery post, then clamp the other lead to the neg post of battery. Then set it to read min/max voltage so the result is recorded. Then do your drop testing of the B+wire and the S wire in the normal way. After you're done, crawl out from under the car and look at what the ground drop test showed (pos if maximal voltage>~0.3V)) on the multimeter.

[@abdul-kabiralegbe5660]

Good idea. Thanks.

[@speedgoat2824]

I really appreciate this guy's approach to explaining what exactly he is doing as well as why he is doing it, I'm not a professional,but been doing 90% of all my car work since I learned how to hold a wrench and I always learn *something * watching his content.

[@ScannerDanner]

Thanks so much! Glad you found my channel

[@speedgoat2824]

@@ScannerDanner I wish I would have found it a lot sooner because it would have saved me a whole book full of cussin..lol

[@AnthonyChew]

Caleb is killing it for the video, thank YOU.

[@dwayneharrald8863]

Bro, after watching this I was able to fix my van in like 5 min .. Thank you so much for posting.

[@ScannerDanner]

Heck yeah! Awesome

[@samuelbane6743]

This is great...to the point, not long and OVER explained... PERFECT!!!

[@ScannerDanner]

This was the shortened "quick tips" version. 😉

[@James-fs4rn]

👍 and we are blessed to have you guys! You're sharing goes beyond making us better technicians. Think of a stressed out single mom that doesn't have the money for someone to be a parts changer on her car and because of you she only pays for what she needs. A proper fix. Thanks for all you guys do!

[@dc5723]

Thank you SD and Caleb, no we are blessed to have you both! Mahalo!

[@luckymutibo9848]

Am a tractor tech,learning tonnes from you sir..

[@ScannerDanner]

That's awesome, thank you!

[@hugh007]

I'm reminded of a no crank that smoked the wiper motor ground wire. Owner had painted the block and the bat ground connection was poor. The only ground the starter saw was through the wiper motor wire. Thanks.

[@snowdoo]

Thanks!

[@ScannerDanner]

Thank you! I take it this video helped you fix your car and it did not need a starter

[@snowdoo]

No, I'm just super appreciative of your clear, and concise testing procedures that you've shared with us. Yes I've used methods Ive learned from your vids, or relearning some I've forgotten thru the years cause it's not my specific everyday trade. So thanks. Have a beer on me!

[@ScannerDanner]

​@@snowdooI'd love to return the favor. Go to the home page of my website and register a free account, then email me your user name and I'll open up SD Premium for you for a month. DO NOT SIGN UP FOR PREMIUM. I'll do that on the backend of the site once I have a user name.

[@snowdoo]

@@ScannerDannerok thanks will do later this evening.

[@billrimmer5596]

I always watch the vids!! Repetition is the mother of retention!! If there is an automotive problem, there is likely an SD video that leads to the solution

[@s8fecracker]

One of your best! Love the burst of burning corrosion quickly emanating from the connection on first crank. Come on Paul, i think you didnt even need the light but to pinpoint exacrly where, LOL. Sadly, i can think of a _dozen_shops that would sell a new starter anyway. Just clean it and/or recommend a new cable with new terminals to CYA after further examination of both ends.

[@BuggysTowJam]

Watched it again and if course I enjoyed meeting Ellie and seeing Caleb in his home with his family. Both great videos by two great guys! Thanks for sharing teach!

[@paulfiebke3909]

Good seen you and your son working to gether, may God bless you and your family

[@andyhodgev.a.g1291]

You’re videos are brilliant, you are clear to understand, knowledgable, and make it fun too, keep going and thankyou from the UK 🇬🇧 😃

[@ScannerDanner]

Thank you! Welcome to the channel

[@ChuckWD33158]

Thanks for the KISS, for those of us without fancy equipment.

[@williammason7092]

You Eric o and mike from wells are good to learn a lot about vehicle

[@frankjohn4302]

Another great teaching moment by Scanner Danner

[@JonathanWhoever]

HELL YEAH! I used this and found exactly where I was loosing. .7v on the ground. The bracket between then bell housing and ground strap.

[@ScannerDanner]

Awesome! Thanks for sharing.

[@salvadorgutierrezr5914]

Thanks for teaching Scannner Danner and son Caleb 🙏🙏🙏🙏🙏

[@bk3043]

This video saved me from losing my mind. Just wish I found it 3 days ago. Thanks!

[@ScannerDanner]

Awesome! What was it? Where was your voltage drop?

[@darrencarey8024]

Great refresher needed that

[@txsurfnturf]

Super informative. Many thanks to you, sir!

[@everardocamacho5063]

Great video Mr danner,you are my hero keep up the good work,cheers from Ontario ca to all you family

[@spiercevaughn]

Awesome vid! Great visual on that testing method. Makes a lot of sense !

[@kenniefernandez]

Greetings Paul and Caleb keep doing well and God Bless you both From Puerto Rico!In Spanish Saludos mi pana espero que esten bien ambos Dios los bendiga a los dos! NO TE QUITES!!!

[@tincankiller6454]

Good video, have had corrosion on the positive post on battery bad enough it will also not crank over but headlights are good till cranking. Thank you for your videos always good info. Stay Safe & Good Luck

[@Stover1928]

Loved the video. I learn something every video i watch. Thanks for sharing your knowledge.

[@mannyclemente7159]

Thank you guys! Sharing knowledge is power.

[@VincentOrosambo]

You are a champ mate. Perfect explanation

[@johnboomer8468]

Thanks for sharing your expertise and passion with another awesome video

[@Isaac-ry7fp]

Thx Danner...from Mexico....been watching your videos and been learning new stuff....really appreciate your time man👍👏God Bless

[@billlangdon9198]

Getting ready to test starter on 07 honda. Great information. Thanks to you both.

[@carloseverette6422]

Great Channel! I have a 97 Tiburon I'm having re done. Having this issue now and the shop just threw a new starter in. Two weeks later and its not starting. I have a new battery and altenator. Must be the wiring or voltage issue!

[@dumisanitembanimtisi8411]

I'm reach. I mean educational,thanks I'm really benefiting from yu guys

[@erno9248]

Thanks...

[@whitetiger8652]

Appreciate the video guys!

[@wyattoneable]

What a great visual.

[@yusufahmed9715]

Thank you for your effort to offer a benefit and knowledge you are the best of the best really we would be proud to be your student thank you again and God bless you!.

[@paulfiebke3909]

Good seen you both keep up the good work ❤

[@labrat6910]

Thank you Paul!!You are awesome dude!

[@everythingbutkoi6898]

Another great video! Cheers danner!

[@alphajalloh6903]

Thank you both of you are so great,bless you.

[@foreverwood1963]

Good job !

[@markferraro5250]

Good stuff SD. thanks again

[@windward2818]

Yes tightening the nut can break through the corrosion, but that is not the finished repair. You would remove the nut (after disconnecting the battery), clean the eyelet, clean up the stud (run a die over it with cutting fluid then clean the stud), and install a new nut. Then you could seal the connection if you wanted (Grote Ultra Seal, Fluid Film, etc.). The block ground repair is a little more interesting in that it could require and completely new cable (wire, lugs, eyelets, etc.)

[@ScannerDanner]

It's been 6 months or more 🙂 It's not a customer so that was the repair lol. But I agree with you.

[@leepennington4649]

Great video guys! 🤙🏻🇺🇸

[@mckoylach1622]

Great one,Paul, thanks

[@ksg7821]

Important tip. Thank you 👍

[@Baypipo21]

Thanks man very informative

[@flightofthefatman]

That was cool bro. 😎

[@BigFrogs4x4]

Love my XJ!

[@victorpecina7137]

excellent video👍👍💯💯

[@MiguelRodriguez-pz8wi]

Thank you for your time and knowledge. I got a 2008 pontiac g6 with no crank no start and it does it when the car have been running for some miles and them after set for a while start with no problems. I purchase a new battery and was going to buy a new starter but after following some of your steps I don't think the starter is bad, check the relay and the had jumper the stater wire and the starter turns. Do you think that may be the control module, like I said before it only does it when the car had been driven for a while. Thank you for all you do. God bless you.

[@ScannerDanner]

Most likely not the module, but an input problem. Will it crank in neutral?

[@MiguelRodriguez-pz8wi]

@@ScannerDanner Yes i does. im going to do some more checking this morning, in order to make it no start I have to drive it for a while. Thank you for you reply

[@careyautorepairs]

Love this video.

[@Pablo_Automotive]

Thanks Paul

[@handrias001]

Good video. Subscribed !

[@ScannerDanner]

Thank you!

[@dannielpizatto7357]

Had a similar problem with my Opel.. But in that case the voltage drop was across the Park-Neutral switch.. Since this part is no longer supplied and already had cleaned the contacts, pushed some springs and contacts and the problem always come back in the middle of nowhere, I wired a relay to handle the crank position. Problem gone :)

[@Paul-cs2je]

Yes it's classic voltage drop. You must replace your srarter motor because it's so corrosion outside and may be inside too. I know this mitsubishi starters they often have problem with ground through body itself. and brush holder have not ground. in this case it's normal to be parts changer😅 ......Paul you are the best! I very appreciate your lessons. Thank you!

[@geraldwardrop]

Thanks for the content

[@mrautoguy8419]

Awesome tips!👍

[@michaelcummings6178]

Great job I wish I knew this years ago

[@mazenramadan493]

Thank you

[@paulstevens6875]

You said there's no current flowing then why was the bulb lit wont a test lite automatically load the circut? Wene it was cranked was there to much of a drop to keep the bulb lit? Thanks enjoy your vids

[@ScannerDanner]

For a starter heavy wire? Absolutely not! You can have one single stand of copper left in that cable and it will have no problems carrying the 200 milliamps of current the test light draws, but Absolutely will not carry the hundreds of amps from the starter. The starter is the real load, not the test light.

[@mohamedshinaishin2822]

Hope you are good sir

[@Sioux459]

Thank you can a problem with my customer car somebody tone change the starter I just tied the wire Start run right away thank you

[@EvandJohnson]

Helpful video but curious what to do when the voltage drop on the positive terminal isn’t isolated to just the stud. Mine is dropping with the tester on the eyelet. Does that mean I have a faulty connection somewhere between the battery positive and the starter? Or could Neutral safety switch/starter relay still be the cause? Thanks! 3:21

[@ScannerDanner]

Yes! Your fault is still in that heavy gauge circuit, just further upstream! Do a test right at the battery terminal next, then if it's good there, look for damage and green crusties on the cable

[@EvandJohnson]

@@ScannerDanner epic! Thank you for the reply!!

[@franklinwadlow2212]

I have a different question What is best to use besides a head lamp from a car to test a load on a circuit for transmission solenoid code

[@ScannerDanner]

I'd use this same test light

[@franklinwadlow2212]

@@ScannerDanner OK thank you I told ATRA I uses a test light but they said didn't provide enough load to check the wire from the tcm to the Case connector to transmission

[@williamlesher5111]

Thankyou

[@anthonynicholls8010]

Thanks. to you and your son 😎😎✌️✌️

[@dadirtydawg7789]

What about starters that have a connector? Which one should have power only when starting?

[@ScannerDanner]

The heavy gauge wire is hot all the time, the smaller gauge wire is the solenoid wire

[@sherrodford955]

Hey danner. I always watch your videos I learned soo much thank you for making me a better technician. I have one issue. I don't think I see any video on starter that are hard to access. For example I worked on one car that is 2009 kia optima the starter is under the intake manifold I didn't have access to wiring diagram or anything. how can you test the starter without removal of intake manifold? please help thank you so much for your time to read this its so important for me to learn I wanna do this right way next time when it comes to like this kind of situation ill be ready to go you know

[@grantbellinger7403]

Beautiful

[@johnthemechanic2937]

Awesome

[@speedgoat2824]

All that corrosion flying off when he cranks it... dang. One of the first things we were taught when I was taking my second year of advanced mastering of car electronics 4, is that corrosion is not good and a small wire brush is your friend. Heh heh

[@bigdog0u81]

What is typical voltage drop to see from the starter while cranking?

[@ScannerDanner]

300-500mv on a circuit that's carrying that kind of amperage

[@bigdog0u81]

@@ScannerDanner thanks man been watching your videos trying to track down a cam position sensor fault no signal. Had it at a shop and they are suggesting a new ECM scanner shows 9.2 volts with the code. So I am testing the battery and starter first because of a low cranking speed then on to the new cam position sensor I had installed

[@MasterMind-zw3zl]

Could it be possible for the car to start, but while at idle the voltage will drop in and out ( like go down then back up then down and back up ) but whole time giving it gas it will stay normal without fluctuating? Can that be a bad connection to starter or resistance in that wire from alt to batt to starter?

[@ScannerDanner]

A starter motor issue like this will not affect how the engine runs. Unless there are fusible links tied into that main stud and there are voltage drops occurring there too. They don't typically do that anymore with fusible links

[@MasterMind-zw3zl]

@@ScannerDanner yes I have a fusible link. 04 LeSabre. 3800... Sorry we're talking on 2 videos now lol .

[@MasterMind-zw3zl]

@@ScannerDanner turned out to be crimped wire on the positive side. Also ignition wire was a tad bit loose but the cable seems to be the culprit when hot.

[@MarioDallaRiva]

Yo, Paul. FYI, the hand gesture you make at 4:23, in Italy, means “your wife commits adultery 😈” Cornuti!! 🤘🏼 🤣🤣 Often used in traffic. Voltage Drop for da win!

[@fernandomoran5979]

Grasias 👍

[@AT_Eng]

nice shades bro....

[@db7664]

I replaced my starter and it would crank but then blow the fuse (tcm fuse) ford focus Could the starter still be the issue even though i replaced it, or is it just a bad grounding somewhere

[@ScannerDanner]

Was the TCM fuse blowing before you change the starter and why was the starter changed?

[@db7664]

@ScannerDanner No wasn't blowing fuse at all, replaced starter because the original one was dead, (car wouldnt turn over at all when turn key on and i used the relay starter trick by putting a wire between the the two terminals where relay sits to determine it wasnt the.starter relay) when I pulled it out too it was badly corroded, and after I replaced it would crank over and the car would start but at same it would blow the tcm fuse and so when I switched car off, needed a new fuse to start again

[@ScannerDanner]

@@db7664 with the fuse blown, does it crank? If no, it sounds like maybe you misdiagnosed the bad starter and this was the real problem. If it now cranks, but doesn't start, then it sounds like you built this problem in. You are at a huge crossroads here my friend. You are either turning left or turning right and the fix is going to be completely different based on that

[@blakenorman4822]

My 85 dodge clicks with key, hook up remote starter to positive battery terminal and s terminal on starter, fires right up

[@ScannerDanner]

So your problem is in the ignition switch, park neutral switch or clutch switch (manual), possible starter relay (if it has one) and all related S post wiring

[@blakenorman4822]

@@ScannerDanner its an auto, tried new ignition switch same problem, ill try your voltage drop tests before messing with neutral safety switch and relay, thanks for your videos, awesome stuff

[@obeerwan]

what test light is used? led or incandescent.

[@ScannerDanner]

Incandescent, i never use an LED type for troubleshooting

[@obeerwan]

@@ScannerDanner thank you. 👍👍

[@scottschmittmusic]

I have voltage on positive but The "S" only lights when cranked? What does that mean

[@ScannerDanner]

When you checked the heavy post. That must be done during cranking even though it's hot all the time.

[@scottschmittmusic]

@@ScannerDanner I've never heard of Heavy post.. what I'm saying is when you had it on the problem post yours lit before cranked.. mine did the opposite it lit when cranked

[@richeager7066]

You were not on the heavy post you were on the crank wore from the ignition that actuates the starter solenoid. The actual current is supplied by the heavy post

[@richeager7066]

The heavy post has a large 4 gauge size wire that comes directly from the positive battery terminal. Although I have seen certain manufacturers now using a large 100 amp wafer fuse on that wire. For decades that wire has always been fuseless. That's just another service department revenue generator.

[@richeager7066]

I would like to see them use a thermal cutoff switch on the starter ad most people don't realize you can't non stop crank your engine if it's not starting. Especially if the battery is low on voltage. The starter still needs the same amount of electrons to overcome engine compression so when the voltage drops the amperage increases and the result is lots of wasted energy in the form of heat.

[@victorpecina7137]

so corrotion was the problem?

[@robertmedina6875]

Yep

[@nicknesler]

Why did the voltage drop on the post, the nut, but not the eyelet?

[@tradesman63]

The corrosion was between the nut and eyelet.

[@zm6301]

Because most of the battery voltage is dropping across the very high resistance in the eyelet so anything that comes after (the nut and post) won't see any voltage when key is in start position, and anything before the eyelet will see battery voltage with just a little bit of dimming because there is still voltage drop across the rest of the starter circuit.

[@rwbishop]

"Why did the voltage drop on the post, the nut, but not the eyelet?" Because 'in this particular case', the source of excessive resistance was located between the eyelet & the starters battery post nut.

[@alejandrovelazquez2378]

👏🏻👏🏻👏🏻

[@romannevazno5147]

👍

[@spanionneo]

I wouldn't disconnect the coils. I'd probably would disconnect the fuse to the fuel pump to stop it from starting. That way I'm not soaking my spark plugs with fuel.

[@rrmech11]

👍👍

[@trashman1694]

Loose nut, wish I was that lucky. Going to dive into the wire harness now haha

[@epicjamaicanjokes8279]

This is an swsome video.

[@ScannerDanner]

Thank you!

[@frankdaniels4364]

I can see sparks coming out of the eyelet when trying to crank!

[@ScannerDanner]

I believe that was dust and dirt flying off the starter from the heavy click? I'll have to look again

[@frankdaniels4364]

@@ScannerDanner yea, take a look. I was on the PC so a big screen. I could barely see it cause of the ambient light. The wire was covering the source from view. Great vid man!!

[@jimflynn5707]

NO, I want a scanner Danner test light, please

[@rwbishop]

Mastery of the lowly low tech test light is one of the most valuable automotive diagnostic skills there is.

[@DJ-tn7vj]

Felt like i saw this video already.

[@ScannerDanner]

You did, this is a shortened version