2004 Cts-V Start Stall / No Comms With Any Modules

Michael Owner/Technician Montreal, Quebec Posted   Latest  
Case Study
2004 Cadillac CTS V 5.7L (S) 6-spd (T56)
Security Theft / No Start

Hey guys i had a car come in the shop this week with a start / stall condition, no communication with scan tool (any modules), cluster dead no radio windows etc...

Found the 10 amp fuse for the passenger door module (in r/s rear fuse box under seat) blown. Found that modules talks on the class 2 serial data line. Went to my sp303 splice pack right beside the fuse box & removed the connector and it started right up. Isolated each module (at the connector / pulled out terminal by terminal) on that line & found that my communication wire would ground when the wire for the passenger module was connected. unplugged my door module & still shorted to gnd. verified my wiring & found this nice surprise right where the wires pass through the body too my door harness. Hopefully this might help someone out this stuff was never played around with by the looks of it.


Geoff Diagnostician
Lahaina, Hawaii
Geoff Default

Great pics!

0 Default Ð Bounty Awarded
Ken Owner/Technician
Phoenix, Arizona
Ken Default


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David Educator
Spotsylvania Courthouse, Virginia
David Default

Good pickup. That would drive a lot of folks a little crazy. Thanks for the good pictures.

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James Technician
Newport, Kentucky
James Default

Good stuff, but what lead ya to blown fuse?

0 Default Ð Bounty Awarded
Michael Owner/Technician
Montreal, Quebec
Michael Default

That’s just kind of my go to first step after I can’t communicate with the scan tool... I always check all my fuses just to make sure my bases are covered from the get go.

+1 Default Ð Bounty Awarded
Bill Owner
Las Vegas, Nevada
Bill Default

I found the exact same problem in the same car. I just happened to move the passenger seat to get a look at the wires and the car came back alive. I removed the metal bracket that caused the problem, after repairing the wires.

+1 Default Ð Bounty Awarded