Low Speed GMLAN/Class 2 No Communication Diag Tips

Customer states multiple electrical systems inoperative.
Fast and accurate diagnosis of multiple inter-related electrical problems using strategized diagnostic process.
2007 Chevrolet Avalanche customer states no start, no crank….multiple electrical systems inoperable.
Chevy GMC General Motors GM U0100 U0101
#mechanic #cars #broken #professional

[@lokyblack3379]

Excellent diagnostic process, you really are a GM master technician, thank you so much for this class 👍🏻👍🏻👍🏻👍🏻

[@DadsGarageDiagnosticSpecialist]

Thank you very much! Stay tuned, I’ve got more stuff coming.

[@Sean-zc3iv]

Thanks so much for posting this. I know how to test my stuff now! also ty youtube for suggesting this video on the home page, woot woot!

[@DadsGarageDiagnosticSpecialist]

Thanks! I’m glad you found it helpful.

[@ibyisabeast]

What a great video

[@DadsGarageDiagnosticSpecialist]

Thank you very much! For some reason this one doesn't get much attention.

[@ibyisabeast]

It made me $1500. Went straight to the airbag module didn't waste time:)

[@enlightenthis3749]

The gentleman talking is sharp, I can tell it in the 1st 20 seconds.

[@DadsGarageDiagnosticSpecialist]

Thank you very much! I appreciate it!

[@enlightenthis3749]

@@DadsGarageDiagnosticSpecialist too bad, you weren't in my area. I am no auto mechanic, many years experience with mechanical and electrical. I purchased 07 trailblazer, radio was half way installed, I'm having transmission shifting issues it seems since aftermarket radio was finished, maybe not related. I've changed both shift solenoids, new fluid, filter. It just seems like it's a power issue, the wiring harness in tranny.pan plastic track wiring runs through was brittle and cracked in places, I removed where bad and cable tied for now. No codes, all fuses are good it appears. The tyranny is like its in limp mode almost, like stuck in 1st gear, I've tried to switch from auto to 4x4 to 2 wheel, makes no difference..works in reverse as well, but it takes higher rpms to get going. I've pulled battery cables and put wires together for hard reset and same thing. I believe all kinds of sensors on tyranny, shouldn't I see some codes with tyranny not shifting? It has the 460L or something like that tyranny. Any help would be flicking awesome, I don't have the funds for shops to look at, I was quoted 200 to 500 to troubleshoot and I simply don't have the funds at this time

[@enlightenthis3749]

I have everything apart,I do have aftermarket radio interface 1952363C11 and found 2 other modules that appear to be remote start or remote entry as well which I don't don't have any remotes or fobs for. They both have inline fuses which are good. I was reading something in forum about aftermarket radio in trailblazer and somebody mentioned a brown wire that needs to be powered otherwise dtc codes and tranny shifting issues, but the thread is old..the other 2 modules are marksman a2 with 2 relays and a directed electronics 457G bypass module. As well as brown wire being powered, it had something to do with starting. Grinding? When I turn the key, sometimes it seems keeps trying to power starter after key is turned back for split second

[@DadsGarageDiagnosticSpecialist]

@@enlightenthis3749 what kind of vehicle are we working on? Year make and model? Yes, on General Motors products usually if you install an aftermarket radio, you have to either leave the network portion disconnected or if you have a better aftermarket radio you have to also install an interface module because the radio communicates to the body control module for door chime and turn signal functions.

[@zombie730]

Outstanding

[@DadsGarageDiagnosticSpecialist]

Thank you for watching!

[@devinkidd900]

For that custom connector you made can you tell me the part number or site for those ends I'm working on a silverado with same problem on the circuit but need the ends for the wires, please and appreciate it

[@DadsGarageDiagnosticSpecialist]

I had some trouble finding an exact part number for the leads I used. Try terminated lead 19119395. Tell me year/make/model and the exact connector ID you’re looking for and I might be able to find the right number for you. Thanks for commenting Devin.

[@jmix2580]

09 Chevy Tahoe DLC states low idle speed and U0109. Replaced the FPCM 3 times and the connector itself and I still have the same issue. Im assuming it’s a CAN Bus problem. Already wasted over $1500 trying to fix this problem. Any suggestions?

[@DadsGarageDiagnosticSpecialist]

Disconnect the battery and test resistance across DLC terminal 6 and 14...you should expect to see about 60ohms....if out of normal range this indicates a wiring problem. If you do see a good 60 ohm measurement then your U0109 would most likely be caused by a power/ground fault to the FPCM. Corroded wiring to the FPCM is somewhat common....check for rotten wiring right at the connector or withing 24" of the connector usually. Thank you. Check out this video here for some tips on diagnosing a CAN network no communication fault: 16 Malibu U0131 No power steering. Diagnose the WHOLE problem! Electrical short testing. HSLAN Tips. kzbin.info/www/bejne/p5vcnaRueJWUfLcsi=iUV3Lw22eh62HOSn