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Mr GOODWRENCH, ASE Certified Technician
Category: Chevy
Satisfied Customers: 184
Experience:  MASTER ASE TECH, 10+ yrs GM experience
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my 2008 chevy 3500 dually says, service trailer brake

Resolved Question:

my 2008 chevy 3500 dually says, service trailer brake has before and it was a 30 amp fuse...fuse is good this it used to do it when traler was it does it as soon as truck is started. without trailer. and when hooked i have no trailer brakes
Submitted: 7 years ago.
Category: Chevy
Expert:  Mr GOODWRENCH replied 7 years ago.

Hello I will be helping you with Silverado. Do you have access to a scan tool? It has set a dtc

Customer: replied 7 years ago.
no i do not. any other options
Expert:  Mr GOODWRENCH replied 7 years ago.

There is a techincal bulletin that has been realeased

#PIT4842A: Trailer Brake Message C1112 And/Or C1114 (Reprogram TBCM) - keywords inop inoperative int intermittent program tow - (Apr 8, 2010)

Subject:Trailer Brake Message C1112 and/or C1114 (Reprogram TBCM)


Models:2007-2008 Chevrolet Silverado
2007-2008 GMC Sierra
Equipped With Intregrated Trailer Brake Control Module (RPO JL1)


This PI was superseded to add labor op. Please discard PIT4842.


The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.


Some owners may comment of a Service Trailer Brake System message displayed on the DIC. When checking for DTC's, C1112 and/or C1114 will be set in the Trailer Brake Control Module (TBCM). This concern may occur with or without a trailer connected to the vehicle.


Updated TBCM calibrations have been released in TIS2WEB to improve TBCM diagnostics for a high resistant short to voltage concern. The Tech 2 can be used to monitor the "TBCM Relay Feedback Signal" parameter located under Chassis/Trailer Brake Control Module/Data Display to help determine if there is a short to voltage. The normal voltage reading is between 3.2-4.1 volts.

If the voltage is higher, the updated calibration will help.

If the voltage is lower, then the updated calibration should still be installed, however additional diagnostics may be needed to correct the concern.


The only way to have this done is to take it to a dealer

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