2018 Silverado Electrical Issues

This 2018 Silverado is having some strange electrical issues and I wanted to keep this diag simple using only tools every tech and most diy people have, a digital multi meter! How successful can you be with just it to track down a fault in a CAN Bus?
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[@moog2961]

Working back late. It looks cold and you still find time to share logical diagnostic procedures to help people improve themselves. You are definitely one special fella Jake. A credit to the trade. Thanks from over the pond. X.

[@arthuraucar3696]

That round connector at the transmission looks very suspicious..! We'll wait for part 2. Blessings......

[@steveo6631]

The interior lights have been upgraded with the new "disco" module... LOL

[@PineHollowAutoDiagnostics]

Aargh intermittent connections that fix themselves are the worst! My strategy is to bisect the bad circuit in the middle if possible, like connector X115 on the diagram. Then you rule out as many other connections as possible without disturbing them. If the circuit is suddenly "fixed" then you know that the problem has to has to be close to where you just touched it 😉

[@autodiagyt]

I can’t remember my reason for not going to x115

[@iloveburittos]

I worked on gmc last week, vehicle was rebuilt title, they have replaced the curtain airbags, as soon as I loosened the headliner I recieved power to panoramic roof, foldable lights for which the problem I came in. They shorted wires with screws through headliner handle that was going next to roof wire harness. Love your work.!!

[@cullenmiller8170]

Gotta love those intermittent electrical issues. I spent two weeks last fall chasing one on a Webasto boiler system. Sometimes just opening the compartment door on the RV fixed it for the day. It finally came down to a broken solder joint in the controller. The one good thing was it seemed to get worse with the temperature dropping outside.

[@timh5887]

GM denotes all the trucks by the fifth place in the VIN number. C is 2WD and K is 4WD. I like the simplification with the DVOM to test and follow the direction of the fault using OHM's. Nice work as usual. See you in part 2! Part 2 should be a bulb test to load the circuit between the modules. Low tech style

[@autodiagyt]

That C and K is only for full size trucks. Colorado and Canyons use S and T if I remember correctly.

[@timh5887]

@@autodiagyt Yes, they are. I was only referring to the 1/2 tons.

[@charliemagoo7943]

GMC uses 1 and 2 on this model

[@donthebrain]

Keep up the good work! I’ll have to fly you up next time I have trouble!

[@ryan.mullen]

Jake. These videos are so good. I used to know nothing about can networks. Then I came across your channel. I’ve probably watched all but maybe 5 videos. I have learned so much. Please keep making these. I can’t get enough.

[@JoseSilveira-newhandleforYT]

Great diagnostic strategy, Jake! Nothing worse than poor or intermittent connections. Part 2 should be a gremlin chase 🙂

[@aranhaydar9195]

Good job 👍🏻 And a great thought process. Although there's a part 2 and i haven't seen whether you've actually done this or not, but I'm gonna say it anyways 🙃 it'll be more efficient to look at you multimeter reading while wiggling the wires to see if the reading fluctuates or changes to being open circuit again. Thanks for sharing 👍🏻

[@bartscave]

Thanks for sharing your diagnostic process Jake. I always learn something new.

[@ysitrim88]

Very good diagnostic cant wait to see part 2!

[@mikeburdi3464]

Another great video Jake and I, like others, like your process! Keep doing what you do and thanks for posting! 👌🏼👍🏼

[@KERTER21]

Excellent work, thanks for the video

[@kyletuttle9064]

Great diagnostic process jake.part 2will be interesting.thanks for sharing.

[@fredautos]

Nice diagnosis Jake. Intermittent faults could be so time consuming!💫

[@robertroberts2484]

Backside connector is my guess as of now, I've seen issues there before. Good luck 🤞😂

[@eddiereichel9354]

I have a Launch Pad 5 with the "smart link" dongle. I love the tool. I did buy it on amazon for cheaper than you can get it from a "dealer " for. At the time I did not know that its a "global" version tool not a USA based tool. With that price difference your paying for the customer support based in USA instead of globally. So far it hasnt been an issue. My previous tool was a launch diagun. I always said I would get an autel so I had a different brand tool. Im really glad that I went with the one I went with. I have used the "smart link" with USB on GM SPS and it worked great.

[@autodiagyt]

Yeah I can't remember the last time I needed a tech support on a scan tool. I usually just grab a different one.

[@mikechiodetti4482]

I know that feeling quite well. "Where did I fix it?" Pull on wire harnesses, move connectors, clean/retention receptacle sides.

[@arthurfricchione8119]

Well Jake you picked a good one this time. Can you just disconnect the harness at the fuse box and check continuity from the pin under the hood to the pin in the cab to see if it’s definitely in the harness. Just a quick guess my brain is pretty scrambled right now taking care of the wifes cancer issues. I’m probably way off if so just chalk it up thanks for sharing. 👍 Artie

[@autodiagyt]

I think part 2 will answer that question.

[@russellhltn1396]

What's needed in this situation is a tool that can monitor the overall connection and alert you when it suddenly goes good.

[@sheerwillsurvival2064]

Part 2 can’t wait 😊

[@charliemagoo7943]

Well... a bunch of other channels would have stopped right there and said it's been to 5 dealers and they wanted to sell an engine for the commx issue. We fixed it and it's good now😅

[@EverythingMechanic]

They could be touching on a little metal bracket that holds the harness near the tail shaft hosing? Possibly

[@anthonysova7117]

Nice can’t wait for part two got to say been awhile since an ohm meter was my go to a problem Is there a procedure after you make repairs to restore RAM ?

[@autodiagyt]

RAM is volatile memory so it populates when the module is booted up.

[@paulspeller968]

oh yeh . has a few of those in my time . even when your being mega careful you can just nudge that loom and bang it clears . then it’s the pain staking task of trying to replicate the issue because you can clean them all but i like to figure out were the problem was . you just know if you don’t it will haunt you for days 🤣🤣🤣🤣

[@paulburroughs1313]

If I was gonna bet a dollar on this, I would bet .50 on that tranny connection and .50 on an as of yet to be located ground connection. I would also check to see if those interior lights are cheap aftermarket led bulbs. Great video when even I can learn something! ✌

[@prashanshan7125]

As always..thanks..!

[@johnavila7942]

Awesome video mr big brain jake

[@JesseAutoDiag]

What worries me when back probing is "pushing the pins into making a batter connection" and not realizing I may of fixed the issue, then have me scratching my head. Now on random thought, I hope some day Autel will sponsor u a MS-909, 919 or Ultra so u can throwaway that blue box 😂

[@autodiagyt]

I don’t think autel sends any high end stuff out to anyone lol

[@8power0]

GREAT VIDEO ,,, I HAVE A NISSAN FRONTIER THAT'S BLOWING A TRANSMISSION MODULE FUSE THAT IT DOESN'T HAVE . CONSIDERING THAT IT'S A MANUAL GEARRBOX BUT IT HAS A TCM MODULE FUSE AND IT BLOWS AS SOON AS YOU CRANK THE TRUCK . WIRE DIAGRAM IS SUPER PIANFULL TO USE SO NOT SURE WHERE AM GOING WITH THIS ONE BUT THANKS AGAIN FOR THE VIDEO !!!!

[@autodiagyt]

Look at a power distribution wiring diagram. It will show you what all that fuse feeds.

[@8power0]

@@autodiagyt THANKS FOR THE RESPONSE... THIS IS A TRULY GREAT CHANNEL !!!!!!!!!!!!!!!!!!

[@ratrodnation]

Great job 👏

[@martinarrieta248]

Grasias

[@ALEX-xd7ko]

Man I just fought a 02 6.6 with a class 2 fault. Everything tested perfectly by meter and scope. But when I would try to communicate with the tcm ( allison) I'd get a no com. I chased it for 10hrs at least. Was chasing the k-line which was for the g.c and t.c.m only . G.c was online t.c.m was not ... no splices directe connection from the data comb . Never did find where the problem was but finally ran a jumper from the d.c to the tcm and all is good .... scary though I've got to start on a 2012 today that's throwing codes for all the engine sensors and dies . But only happens when the owner is driving alone ????? I cant recreate the problem, not even with him driving and me miss dazying.

[@djosbun]

Jake, around the 8:00 minute mark you said that you had terminated leads hooked to the DLC. Are you saying that these two leads each had 60 ohm resistors integrated into them? Thank you.

[@autodiagyt]

No terminal leads. Like leads with terminal ends on them.

[@jacoboortiz3513]

I kind of have the same problem with my 2018 Silverado and the dealer can not find the problem. How can I get you to look at it? I live in Lake Dallas Tx

[@autodiagyt]

I’m in north Alabama so that would be a pretty long drive for you to get it to me. You could reach out to Dallas Auto Diag and see if he would figure it out for you. He is a friend of mine and very smart guy.

[@russellhltn1396]

I'd suspect something between the junction block and the transmission. 0.9 ohm strikes me as a bit high.

[@autodiagyt]

I’ve also got an extension on my leads and stuff so 0.9 isn’t out of the ordinary.

[@russellhltn1396]

@@autodiagyt More extensions than when you checked the junction block? That could explain it. But if it was the same, I'd think that would be an indication of where to start.

[@Max-j2r]

❤❤❤❤❤

[@aymenmohamed1134]

👍👍

[@ibrahimnaji3018]

What is your advice to someone who has completed the electrical basics, electrical circuit malfunctions, and inspection methods with a multimeter and telescope, but in modern cars I see that I am incapable of diagnosing health conditions. I do not understand the rules. Your advice?

[@autodiagyt]

I diagnose most of my vehicles with a oscilloscope.

[@ibrahimnaji3018]

@@autodiagyt Yes, if the systems are understood, diagnosis can be made. I now lack understanding in modern vehicles, the connection of computers and their communication with each other. Can you recommend a book or someone who explains that?

[@excalibur-km9ff]

These have problems with resistance at the battery cables. Test for voltage drop across the battery cables….Causes these exact same issues. There is a TSB for it…

[@autodiagyt]

2018 would have the upgraded cable by now. When this body was new in 14 and 15 the cable mounted to the bell housing end and they changed it to a shorter cable that bolts in front of the starter. I don’t think I’ve seen one of the new designs have the issue yet.

[@peterbenson3776]

That transmission connector looked rough

[@autodiagyt]

lol I thought it looked pretty good compared to most of them I see lol

[@georgebell3964]

👍

[@larrystephens7437]

Is there a reason you didn't back probe pins 6/7 and 4/5 checking for 120 ohms on X61A?

[@autodiagyt]

My check from the dlc to the ECM told me I had an issue on 1 wire only. The goal was to trace its connections from the dlc to the ECM until I found the high resistance. On X61a I did check X4 pin 5 but X2 pin 7 was on the backside of the box and you have to unbolt it and flip it around to check it. I felt like that would be to much movement and might disturb the bad connections.

[@firstlast---]

​@@autodiagytI'm hearing that you can't check resistance at the dlc on vip vehicles. Is that true?

[@autodiagyt]

@@firstlast--- not in the vehicles with a gateway that isolates network traffic from the dlc. 2019 Silverado has this type gateway.

[@firstlast---]

@@autodiagyt That's what I thought. I just got back from one of the gm training centers last week and they were saying they're having problems bugging cars on vip vehicles because the topology allows modules more than one path of communication. After a key cycle everything goes back to normal. Skynet stuff lol

[@steveo6631]

@@firstlast--- what does "vip" stand for?.. Noobie here...

[@johnbonifas6040]

Couple minutes into it and it seems like a bad ground going to the body to the engine

[@kevinbent7655]

What would be the case if you had 60ohms at dlc

[@autodiagyt]

If it was 60 the network would be complete on this vehicle and it wouldn’t have this issue.

[@kevinbent7655]

@autodiagyt ok thank you, it would be a power or ground issue maybe

[@tyberzann9713]

The part with the radio: The Radio can communicate, but what you are referring to is the HMI. Just my two cents :D sorry.

[@autodiagyt]

I'm not sure what part of the video you are referring to. The prescan shows no communication with the radio or hmi.

[@tyberzann9713]

@@autodiagyt sorry, was a Bit to Quick for myself. Forget every time the HMI is part of the radio-com in this topology and MY.

[@mike-yp1uk]

Sma had a crusty ground from the body to frame

[@robertofkennedy]

Disco mode