2003 Hummer H2 Throttle Communication Codes

Come with me as we finish up this Diag. The code we will be focusing on is the P1518 PCM to TAC module serial data circuit.
This circuit as we find out in the video is not connected to the dlc but instead is a dedicated communication line between the PCM and the TAC module. Scoping the communication lines and powers/ground wire we found out the powers and ground remain in good working order when the problem happens but the communication lines get shorted to power. At the end of this diag we find the root of the problem. the hydroboost pressure line has rubbed through the harness at the pcm and caused a power wire to short against the communication line.
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[@billyyoder8171]

Thank you Chad and Val. Good job again. Have a blessed and safe week to you and your family.

[@hungryhungryhummer]

This was FASCINATING! What a hard find.

[@spelunkerd]

This one would have been easy to fall into the trap of buying a new module. Fun diagnosis!

[@malcolmlittle3725]

i am very impressed. That was some fantastic troubleshooting. Wish all shops had Technicians with your skills. Thank you so much for showing us H2 owners that some issues could be caused from harness Trouble. Its so nice to see good old fashion trouble shooting instead of just troughing parts at problems. using modern tech of coarse but getting right down to the root cause. I will be sharing your channel with my buddies.

[@djosbun]

I am thoroughly impressed with the quality of your videos. It is obvious that your diagnostic skills are superb but I also appreciate the professional audio quality and how you present the information. I am able to learn a great deal from your videos and they are a pleasure to watch. Thank you!

[@markferraro5250]

GREAT CASE STUDY PM

[@bartscave]

Wow Chad! Great diagnosis.

[@codysautodiagnosticsprogra8706]

Nice work Chad.

[@ThePracticalMechanic]

Thanks Cody, the other shop told me it only acts up one or twice a mile. I'm glad It acted up in the shop so I could pinpoint it.

[@johnwebb9176]

Great find man!

[@johnpyun1]

thank you that was best diagnosis

[@michaelh4326]

Excellent video

[@ThePracticalMechanic]

Thank you very much! Have a wonderful new year.

[@matthewsmith5937]

I have a 04 h2 I think I may have the same kind of issue. Thanks for the Help..

[@ivandrago2557]

Excellent job, well done. Explanation is perfect.

[@jeff5179]

Having same problem gonna look at this on mine 2mor thks

[@robertevans6023]

So did you ever fix the issue cause mine is doing the same exact thing

[@ThePracticalMechanic]

Yes. The hydro boost hose had rubbed through the communication wires.