How to locate a short in a wiring harness (visual inspection)

I teach this to my students all the time on where to start looking for a short to ground in a wiring harness. "Look for Points of contact" and "DO NOT start wiggling and pulling on the harness without doing this simple visual inspection first!". It is the difference between accidentally and temporarily fixing your problem and not knowing exactly where it is, and pinpointing the area of the fault right away.
Below is the original video this little clip was pulled from
2006 Cadillac DTS Shorted 5v Reference Circuit
• How to check the 5v re...
Typically a vehicle will not run with a shorted 5v reference circuit but in the case of this Cadillac, it has 2 separate 5v regulators, so it can still run with one of them shorted.
For more information on this topic, I have written a “field manual” called Engine Performance Diagnostics which is available at www.scannerdanner.com as an eBook or paper book.
Want even more diagnostic training? Whether you are a DIY trying to fix your own car, someone looking to become an auto technician, or a current auto technician that wants to get more into diagnostics, subscribe to ScannerDanner Premium www.scannerdanner.com/join-sc... There is a 14 day free trial.
On ScannerDanner Premium I will bring you right into my classroom at Rosedale Technical College. You will find page for page lectures taken right from my book as well as exclusive classroom type case studies. What is so special about these classroom case studies? I pull live problem vehicles directly into my classroom and we troubleshoot them in real time, using and applying the theory and testing procedures we learn during the classroom lectures. There is no better on-line training of how to troubleshoot automotive electrical and electronics systems anywhere!
Disclaimer:
Due to factors beyond the control of ScannerDanner LLC, it cannot guarantee against unauthorized modifications of this information, or improper use of this information. ScannerDanner LLC assumes no liability for property damage or injury incurred as a result of any of the information contained in this video. ScannerDanner LLC recommends safe practices when working with power tools, automotive lifts, lifting tools, jack stands, electrical equipment, blunt instruments, chemicals, lubricants, or any other tools or equipment seen or implied in this video. Due to factors beyond the control of ScannerDanner LLC, no information contained in this video shall create any express or implied warranty or guarantee of any particular result. Any injury, damage or loss that may result from improper use of these tools, equipment, or the information contained in this video is the sole responsibility of the user and not ScannerDanner LLC.

[@ScannerDanner]

Just wanted to remind everyone in case you missed it. This was pulled from an older case study video. You can watch it here kzbin.info/www/bejne/q6rRlImwlK10qqM (read the descriptions of my videos!!) I am going to start doing this when I have time, to help me teach my classes. There are specific procedures that I teach that I want to emphasize in class and I want quick references to them. You will see more of these in the future. Thank you guys so much!!

[@BigD1395]

ScannerDanner which part of your scope after you using? Main harness leading into the ECM, right,?

[@renebriones995]

🎉🎉🎉🎉🎉🎉🎉🎉🎉🎉🎉🎉🎉🎉🎉🎉🎉🎉🎉🎉🎉🎉🎉🎉🎉🎉🎉🎉🎉🎉🎉🎉

[@howardlovecraft750]

@@BigD1395 I don't think your gonna get a reply......

[@NewLevelAuto]

Amazing how many cars we can fix when we start with our hands in our pockets . Great video as always

[@manuelsalvatierra2940]

What percentage of cars are misdiagnosed? I'm sure it varies, but just a wild guess

[@stewartsaunders7703]

I was finally able to find the short in a Polaris ATV thanks to your video. I couldn't figure out where the short was to save my live. Yep it was in the main harness where it was zip tied to the frame against the edge of a metel bracket. Almost took it to the dealer. It would have cost a small fortune. Thanks again Danner.

[@ScannerDanner]

Heck yeah! That's awesome

[@MrDdiaz84]

Hey thank you so much for this video . I found the short that 2 mechanics couldnt find . I put in another used harness and fixed my transmission shift issue !!!!! Thanks man !!!!😉👌

[@robertweir9034]

First realizing there are bad motor mounts, then happening to see this contact point and of course knowing the wire in question is in the harness helps a lot also. Lol. Thanks for sharing Mr. Danner.

[@hittz8331]

A great analysis and find!!! It was suspected of my VSS wiring and found by my Mechanic. Nice demonstration and video ScannerDanner. Very informative. Thanks Much

[@TheAutoTech]

Visual inspection can go a long way! Good work Paul!

[@scientist100]

Only if you can see all harnesses lol, some are really hidden under the engine and engine covers. I have ordered the Power Probe tool that checks for opens and shorts to mitigate this

[@SyberPrepper]

This is such a great tip and reminder! Thanks for the video.

[@ahmedahmed-dt5ew]

hi ScannerDanner ,,,,Egypt . Cairo here lol i keep learning from you i do watch everything you say now i can fix my friends car for free

[@mddell58]

*Wow! Great video, Paul. A year's gone by, & I'm still without my minivan, or any transportation. Very depressing, to say the least. Have a great day!!*

[@electronmarkboggess63]

Great find .. the majority of drivability/electrical issues I see in the fleet I service is caused by extreme movement of the harnesses causing short to ground like this and broken wires mostly right at the pigtails

[@MagaRickn]

Wish my mechanic would do this rather than just want me to buy a complete new wiring harness from GM dealer! :()

[@richardarchuleta3596]

You just said the answer in your text not your mechanic your dealer don’t forget mechanics get fucked by flat rate and dealer fucks the customer both gets fucked so they can make more money

[@jwilkers1]

Very good tip to look for contact first thanks Paul

[@mrkttrdr2919]

Awesome sauce boss, good back to basics reminder.

[@30kendel]

Awsome find paul! Big thumbs up!!!

[@mostlymoparih5682]

Excellent point and great vid, Prof.

[@billyyoder8171]

Thank you Paul. Bless You Brother.

[@jeremieparker5703]

Great job Paul

[@hillsofva739]

Good catch man my old 740 needs some wire work .

[@Ben-ww1zq]

Thank you for the information, wish I had one of those tools, but you have given me a direction coincidentally I also have broken motor mounts

[@Jimbo9008]

I thought I was the only one to use my pocket pry bar as a pointer when showing someone something. I can't function without a pocket screwdriver. I sometime reach for it on the weekends when it's not even there. Nice job finding the short.

[@SmittySmithsonite]

Great stuff, as always! 👍

[@wyattoneable]

Amazing that such a small issue can create so many problems. But a lesson I will remember for sure.

[@denistodorov4275]

great video , thanks for yours videos ,you are the best!

[@theadventuresofjavier8698]

Big thumbs up Paul.

[@noelhernandez5016]

Love your videos

[@Pablo_Automotive]

Great tip Paul, thanks Paul =)

[@boom192channel]

Very good video.

[@starcityrc3298]

I always buy color tubing and clean up the wiring. Bright colors help you find it and also see any damages etc.

[@michaelr6205]

Hey Paul are you using the Lab scope or Graphing multimeter setting to view the 5 volt? Thanks.

[@dang2436]

Hey man grey video .! If I were to take it to a shop what specific shop should I be taking it to?

[@HUCKLES42]

hi ScannerDanne sorry sir i dont know your name but i been watching your videos i want to congratulated you for the excellent videos with very good info i used it be a BMW master tech good stuff .. thanks

[@D-TECH886]

Hi scanner after long time you share some thing. We were waiting

[@robertpope3619]

Is this why using a lab scope is better because it will pick up that short on the screen when performing a wiggle test or do you think a DMM would've showed that as well?

[@user-qp3pc3xt1g]

Awesome thanks

[@jesusmalagon4336]

Thanks paul danner

[@arctican7483]

GOLD!

[@manny873]

I have a 05 Honda Civic, Check engine light is on . Code reader says primary 02 sensor . Changed the 02 censor but code won’t go away . Could there be a short in the harness ? If that’s possible would it be the 02 censor wire in the harness ? Or is it also possible that it’s a different wire ?

[@pirihern9329]

This my be my issue with the subie sti po448 will have to trace out and remove intercooler muy bueno snapon versus top notch scanner mucho denero

[@nickayivor8432]

KNOWLEDGEABLE Sir ScannerDanner My Mentor Sir ScannerDanner 👍 and love it From Nick Ayivor from London England UK 🇬🇧 Good Evening ⏰️ 19:48pm

[@kirkabrahamson1148]

Always check the basics. Good reminder. Wheres the comment from Mr Thumbs Down to tell you how to improve your videos lol

[@rrmech11]

I remember that video from the day. The vehicle had 2 separate 5 volt references. What happened to your brother James? Haven't seen any more of his vids.

[@9Yan1nick1]

Hey buddy, I think my alternator armature is what is screwing with all of my electrical problems, could this be it

[@ronringler4286]

Good video l like

[@theman8795]

I have a vehicle, the instrument cluster lights for the guages do not turn on so i cant see them in the dark, but when i drive after about 20 minutes they slowly start turning on. What is causing this?

[@timramirez4121]

So what was the graph hooked up to?

[@theboysplayingcod2959]

Art

[@stevenjames7073]

This must be an old video since we got the old snap on scanner...Cadillac engine mounts

[@jeremiahlynn7537]

How did you fix it

[@richardcranium5839]

just more proof you need a scope to deal with newer cars

[@captainplan3t250]

What u connect to scope to

[@antn8387]

what kind of snap on device is that

[@juanrodriguez-ry6yt]

these days even the motor mounts can have shorts i'm trying to be funny

[@jamesu]

Not real funny when electronic Nissan/Infiniti motor mounts short and damage the computer.

[@madmotorrepair1748]

#Contact Point

[@jimmyrey385]

Sometime is hard to find it

[@carslover3509]

Master

[@CrystalGeyser69]

That small of a cut would stop the wire from working totally or the voltage just drops?

[@ScannerDanner]

A short to ground? Absolutely, doesn't matter how small the cut is

[@CrystalGeyser69]

@@ScannerDanner currently having a no crank no start issue with a 2006 Chevy Colorado . There is a small hole just like this on the dark blue wire coming out of the bcm. I covered the wire in electrical tape and the dash still isn’t communicating with the engine light . Should I fix the wire in a different way?

[@waynewagers3100]

I'm needing information on how to find a short in wiring on a 95 Grand Cherokee Laredo jeep 4.0 engine

[@116gamers]

My Toyota celica stop showing gas amount and door locks stop working all at the same time and all fuses are good :( thanks for vid I’m trying to fix it

[@ScannerDanner]

you need a good wiring diagram my friend eautorepair.adtrk.biz/?a=10817&c=24&p=r&s1=

[@MJCenac76]

Dude, I just think I fried my 92 ram charger. I am freaking out. Tried to fix a fuseable link, cranked it perfectly. But I put a relay into that furthest back relay outlet on accident, cranked it and everything started smoking. I need advice on what to do.. I am praying I didn’t just fry this truck.

[@ScannerDanner]

You probably blew that same fusible link. Need to find out what all is on that circuit and start doing some visual inspections Pay the $20 and get yourself some good wiring diagrams. These are the same ones I use. eautorepair.adtrk.biz/?a=10817&c=24&p=r&s1=

[@Iknowaboutroaches3350]

I have a 2001 jeep grand cherokee 4.0, I just noticed that when I jiggle the crankshaft sensor harness/pigtail it will cause the engine to sputter and miss, has anyone else had this?

[@ScannerDanner]

Typically, this is from a bad sensor. When you wiggle the pigtail or the harness, you are putting stress on the male pins in the sensor itself and where they attach to the little circuit board inside of the sensor. It is very common to mistake this for a wiring or connection issues. To be sure, disconnect that sensor and do a visual on the female terminals, snug them up using a small T-pin if you need to, then also look at the harness real close and make sure there is no rubbed through insulation, exposing copper wire. If that's all good, make sure the sensor itself is no loose on the hold down bolt

[@Iknowaboutroaches3350]

@@ScannerDanner ok I will do that, thank you so much for your response, your knowledge is amazing and greatly appreciated.

[@billk5727]

Great find Paul! Could a standard digital voltmeter show this as well??

[@throttlebottle5906]

if it has a fast graphing function yes, many standard/cheap meters are slow and may not show the loss/drop. Using a 5 to 6 volt low power incandescent bulb may be better to visually see the flicker, a 12V test light may work if it's bright enough on 5volts or obviously any oscilloscope :)

[@robertweir9034]

Bill K Question is, where would you attach the meter using a voltmeter?

[@billk5727]

Robert Weir Same place Paul has the scope attached to

[@billk5727]

throttle bottle Ok I got it

[@robertweir9034]

Bill K OK, then I think a meter should work.

[@jelotech579]

NicE brO

[@f.k.b.16]

I come because my wife's friend (single, older, broke) has an 05 Sedona. She had the power steering pump changed. The mechanic noticed a mouse ate through the insulation of "some wires" and replaced the section of bad wire. Now, you guessed it, the transmission slams into 2nd then enters 1 gear only limp mode. She described her issues but didn't mention that it was just worked on. She mentioned that her tach stopped working so (before I knew the back story) I went to change the ignition failure sensor hoping for a long shot fix thinking that might be causing the transmission issues. That's when i noticed all the wiring to the transmission was "new". So my question is: How the world can I diagnose the wiring without a wiring diagram? The mechanic is playing dumb to the repair now claiming her transmission went bad right after the repair. (Well... Not playing) He actually spliced wires and ran new ones so the plug has 1 new connectors inside the housing ran with 6 inches of new wire connected to a blob of the original wiring harness. So it's all plugged in the correct ports but I don't know if he mixed up the pins.

[@ScannerDanner]

He may have missed something and it is not the harness that was replaced. That is my guess

[@f.k.b.16]

@@ScannerDanner Thanks. Yeah it was not the harness that was replaced. He re-pinned the connections and then ran wires back to the harness where he spliced it. My thought is he hooked the blue wire to where the red wire should have went (and so on). I'm going to head to a junk yard and take a ton of pictures and try to recreate the correct wiring.

[@ScannerDanner]

@@f.k.b.16 did you fix it?

[@f.k.b.16]

@@ScannerDanner no... Either the wires faded or the colors didn't match the wiring diagram I found. I did try verifying colors match where it was spliced but I'm still not sure the connectors weren't re-pinned. The one I'm most concerned with is the real speedometer sensor on the side closest to the flywheel. Do you think that sensor would cause gears slamming? Thank you for asking!

[@throttlebottle5906]

most important automotive/hvac/appliance/etc. tools? ears!! and eyes!! of course that does take some years experience.

[@AhmedAli-bo2pm]

Hi I am from Libya.... where is connected the ocillscop with car ..until you know the problem

[@NoferTrunions]

MY BAD: I would just wrap the harness and eliminate the rub.

[@keepthinking2666]

just like the 2002 malibu shorts behind engine ignition wires melt and short to heat shield stupid chevy

[@fernilu6998]

First my friend.......

[@fernilu6998]

Love your videos

[@Scott-xh7wd]

2001 pos Blazer came in from another shop. Check valve went bad on air pump, exhaust burned through a rubber hose melting about 80 wires together. If I could attach pictures to these comments I would. Straight up waste of time. Customer wanted it fixed.

[@arbez.nation]

Here - First or whatever

[@richraven3828]

Correction: How to find a short using a $5,000 Snap-on scope that you will probably never get your DYI hands on! Translation: Forget trying to do it yourself and come to our shop, pay us a ton of cash and we'll do it for you!

[@ScannerDanner]

You have to look beyond the tools I'm using and apply these techniques to what you have. A simple code reader, multimeter/test light and a wiring diagram is all you need.

[@lockdowntv874]

@@ScannerDanner You should change the title to: How to locate a short in a wiring harness (Using a Scope and visual inspection)

[@ScannerDanner]

@@lockdowntv874 or voltmeter right? You didn't need a scope to show this voltage drop on the reference circuit. Sure the scope was nice because you have a signal trace you can look at, but it wasn't needed. BTW, this video was pulled from another full length video showing all of the steps involved. Thanks! kzbin.info/www/bejne/q6rRlImwlK10qqM

[@luisbrown1643]

You don't even talk about which vehicle you working on

[@ScannerDanner]

Check the description, this was pulled from a full length case study and it is linked in there. Thanks!