Turn Signals Not Working Diagnostics (17 GMC Acadia)

In this video you’ll see the Professor go over a diagnostics that Andrew recently did on a 2017 GMC Acadia. The passenger turn signals don’t work on the front or rear. They all went out at the same time. The drivers side and hazards work perfectly. He will go step by step through the test plan and then show you the fix at the end. We hope this helps! Enjoy!
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[@EATSLEEPFARM]

This channel is one of the best automotive channels on youtube. Showing the full process is so refreshing to see. Keep it up guys 👍

[@ThunderbirdRocket]

That was awesome ! You have explained everything about this diagnostic process very very well !! And shout-out to the videographer for bringing us excellent footage !!!

[@AlanBurnham]

Maybe it was done off camera but I didn't see any verification that the problem wasn't in the BCM connector before the BCM was called. IMHO, before condemning the BCM, a small amp test light should have been used to confirm a small load could be carried between the front of female terminal in the wiring harness connector and the point where the wiring harness was tapped for the scope. Great methodical diagnosis other than that. Enough detail to understand and enough edited out to make it short enough to stay interesting.

[@mikesautomotivediagnostics8080]

By hooking your test light to ground, and touching the input pin while watching the input data, it would show active if the BCM was good.

[@sanagavizharan92]

There's a tsb on these where the ac box drain can leak out ontop of the bcm and cause some interesting electrical issues along with green crusties in the connectors

[@johnmitchell2741]

I believe they should be looked at first before attempting any repairs could save you a lot of grief

[@vickenkaragozian2041]

The Escope shines always. The body control module should send 12v to both left & right turn signal circuits when turn signals are in neutral position. When you turn the turn signal to left or right the switch will ground the wire. The Escope has bias voltage negative 2.5v. That's awesome, so when you have a the test lead connected to a wire the red light should turn to gray light. The great thing is if you loose connection the voltage will go to minus 2.5v , but if the circuit touches to ground or if you have a short to ground the voltage will go to 0 volts, That's how you can tell if you have a shorted wire or bad connection. Awesome feature from ATS scopes.. Thanks for posting a new video 👍

[@joeydeemendoza]

LOVE yalls diagnostics videos you guys are absolute gurus thank u for sharing your knowledge with us!

[@spirokattan3655]

Nice diag! Thank you for taking the time to explain diag path. Excellent! Please keep them coming.

[@DependableAutoTruck]

really good video great information wasn't sure which way to go after the scanner didn't show anything. it might have thrown me down a rabbit whole, i probably would have applied ground on the wire for right side at the BCM to see if anything happened. thanks for sharing learn something either different or new every time i watch a video from you thanks again

[@calebmohler3082]

Great video, I'd have no problem using a test light to B+ and making sure it light when switch is in right position........

[@martinboucaud679]

Great diagnostic my friend. That was awesome. I love it. Thank you for sharing this awesome job.

[@zekzygaming5128]

Glad to see that the volume is just fine now, thank you guys.

[@GUE5TPA55]

Very in depth, this is exactly what I was looking for.

[@mod_incllc3235]

Great video! Love that you focus the content mainly for working technicians. There are plenty of DIY focused channels but less professional oriented content on KZbin. Thanks!

[@personalimpressions4749]

Great video on the importance of verifying the problem. Some would’ve replaced the blinker module by looking at scan data.

[@agoodneighborautorepair2176]

Very nice explanation and information(I think you can test the switch circuit with va low amps LED lamp 12v

[@Mdavied2023]

when you started diagnosing using Scanner, you checked if there was any signal from switch to body module. my question.........why you didn't command on active test the right signal using scanner before using scope? when the control body module didnt see any signal i thought the problem is between switch to the body module i thought the diagnosis procedure using scanner is ..........check signal using switch ........then command active test the actuator or motor to eliminate it. i really love your explanation and and strategy when you diagnosis thanks

[@user-ve8mx3zi6k]

If I'm thinking correctly, a grounded test light applied to the left input likely wouldn't light due to the small current reference voltage output by the BCM. It seems that it would toggle on that circuit though, which could be used as a diagnostic method for the right side. But, as clearly mentioned, an accurate diagram and understanding of circuit operation is critical. Personally, test lights and power probes and other pointy circuit damaging type tools make me cringe. Keep up the good work, videos are excellent. Al

[@pontiacsrule8761]

Great video as usual. I'm a DIY guy. i know that's the way things are today on cars. Imagine explaining to a customer the repair bill for a right turn signal. Long gone are replacing the $2 1156 taillight bulb. People don't realize what goes into all that trouble shooting & programming. Great video as always. I love these videos from Royal right to the point diagnosis. If you guys have a shop, can you estimate what that repair would cost in today's times? Thanks....

[@jameslewis1175]

Man you make it so easy to understand this. Thank you

[@robertmobileman8304]

great video and explanation of diag process, thanks

[@James-fs4rn]

👍 great work as always! Thanks for sharing.

[@AAB371]

Great video and explanation

[@Santiago_Ordonez_]

Excellent case, in my opinion the only thing missing was the test of the turn signal actuators.

[@PaulCTownsend]

Great video and info thank you.

[@clivewright7778]

A power probe is a very dangerous tool in the wrong hands . I love the power probe but there should be more warning about pushing that button

[@danielrobertharrison7827]

You could make up your own 1 2 3 4 and 5 volt test lights

[@michaelt8330]

Another great video!

[@johnmitchell2741]

I have an XTool d7 I can light up each individual light on my 2018 Chevy Cruze using the special functions tool on the scanner So that would eliminate the BCM and all the wiring,and connectors from the BCM to the lights. that's a big diagnostic time saver

[@user-zl5jz5fg3f]

Great and informative another excellent video well done

[@mikedavidson2117]

Hi may be a led test light would be safe

[@ryan.mullen]

Such a great video. Thank you for what you do. 🙏.

[@IamReadyToRock]

nice video . From Peru

[@tomerikstokness276]

You could also just jump the pins in the plug to the switch ,to check the switch. and Ohm between the switch-plug and BCM..

[@stansmulders6126]

Learned some thinks thanks

[@johnmitchell2741]

Somebody in the comments mentioned you should always pull any TSB before starting down the diagnoses rabbit hole.🧐

[@overload3996]

OTC 3631 PCM safe test light could be used along with a meter.

[@philh9238]

What caused it to fail? Over current from the turn signals?

[@johnmitchell2741]

Wouldnt a DVM give you the same readings to help diagnose the wiring and connectors if you can't afford to buy a scope.Sorry looks like you answered my question The scope just makes it easier

[@tnamen1307]

Very simple issue. There's no 12V send out from the BCM for the right turn signal switch. That's why the scanner shows -2V.

[@ront7795]

I do have a question, hopefully I don't offend by asking. Why did you not use the Launch scan tool that you did a piece on about a month ago? I saw you using your Snap on tool. I'm just a DYI guy that likes to fix things when possible myself & am asking for a little reassurance before dropping 400 plus. Thanks for your videos & your time. 👍

[@theroyaltyautoservice]

One of our shops still use it daily but mainly for pre scanning vehicles when they come in. The one at our other shop locked up and won't turn on. Ive got to get with Launch and see 8f they can fix it.

[@ront7795]

@theroyaltyautoservice Thank you so much for getting back with me! Means alot, greatly appreciated. 👍✌️

[@johnmitchell2741]

My friend bought an XTool d7 and I can make it turn each individual light on in my car,so that would eliminate an awful lot of diagnosing time . I liked it but wanted a Bluetooth dongle-type scanner so I bought an XTool A30M I got it on sale for $170 but it will not program keys and you have to use your own Tablet it will also record and give you a health report on all your modules. Just Saying, do your research

[@ront7795]

@@johnmitchell2741 Good info John. I actually ended up getting the Xtool! Felt it was a little more user friendly & better options for the DIY. Does a ton of stuff.

[@johnmitchell2741]

Cool glad I could help@@ront7795

[@tomd5010]

Yet another reason I’d never buy a GM vehicle. A simple turn signal not working ends up costing for a diagnosis, a new electronic module, installation and programming. Got to be hundreds of dollars. No reason it needs to be that complicated, although the video was informative. A turn signal should need power, ground, switch and bulb. There are a zillion of old vehicles driving around with the good old setup working just fine.

[@martinarrieta248]

Grasias

[@CareyH64]

Expensive flasher.😵‍💫

[@DependableAutoTruck]

what i would like to understand how doing the turn signals this way is better than the old days when you didn't have a computer such a simple circuit made complicated with electronics.

[@AlanBurnham]

Well, it is way too difficult to hold the lane change position on the turn stalk; we need a computer to do 3 blinks. I'll take a manual transmission and mechanical turn signal flashers any day but a basic vehicle like that won't sell...blame long term financing for that. Most people wouldn't pay 40k+ for a car if they couldn't finance it for several years.

[@DependableAutoTruck]

@@AlanBurnham the ford guy that fixes all the late model fords just fixed a F-150 turn signals quit chain reaction soon vehicle would not run $5,600.00. the tail light lens was like $1,600.00 and it didn't have the lane assist module in it that was extra. no reason a lens should cost that much

[@AlanBurnham]

​@@DependableAutoTruck I saw that video as well. Most people that buy those complicated vehicles new will probably never see the crazy repair bills; when the warranty runs out they buy a new vehicle with even more fanciness. I'll admit I wouldn't buy a new vehicle without power windows so I'm probably part of the problem I complain about.

[@johnmitchell2741]

Ive read the manufacturers are doing it to cut down on the amount of wiring and connectors which also cuts down on weight and if your good with a scanner it can cut down on diagnostic time

[@DependableAutoTruck]

have you looked at the new vehicles take the 5.3 look how much wiring there is compaired to earlier years mor and more wires@@johnmitchell2741

[@TB-jy5nr]

Hoi you all nice video Can you open the bodcontolmodul?

[@thomasmihm7550]

I know this is a GM but is there a way to program Dodge trailer wiring that factory harness without going to a dodge dealer on a 2014 Journey?

[@marshall1157]

i miss the simple flasher type turn signals

[@johnmitchell2741]

Im just curious Did it have LED Lights or incandescent bulbs

[@aymenmohamed1134]

Awesome

[@michaelt8330]

How did you determine that it was UHF?

[@theroyaltyautoservice]

It's been a couple of weeks but I believe that information was in the RPO codes.

[@davidbarnes9184]

I appreciate your video but man brother..I'm not that far advance..just need to fix it

[@BattleForTheHotel]

difficult to fix, in old cars you replace the lights if they are burned, or the switch and that's it.

[@matpolson4411]

My only question is what made the bcm fail in the first place?

[@theroyaltyautoservice]

Unfortunately we don't know.

[@johnmitchell2741]

Someone said in the comments there was a TSB on this issue saying water from the ac evaporator drain was dripping on the connector causing it to corrode @@theroyaltyautoservice

[@TucoolRacing]

Hello, may we know how can we send products to you for testing? Thanks.

[@theroyaltyautoservice]

You can reach us through Facebook Messenger. Royalty Auto Service St Marys GA.

[@johnmitchell2741]

I would have tried the 4 ways just for the hell of it to see what happened

[@tnamen1307]

If it's was my vehicle, i would have simply buy electronic relay parts, and rewired with the BCM to actually work for both left and turn signals. Only 10 dollars will FIXED the issue.

[@ua7pyro591]

Typical gmc quality, surprised the owner even noticed they don't work!

[@johnmitchell8925]

Could probably do with out the Click bate