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Thursday, April 25, 11:57:17 [ Login ] [ Contact Forum Admin ] [ Main index ] [ Post a new message ] [ Search | Check update time | Archives: 1, 2, 3, 4, 5, [6], 7, 8, 9, 10 ]

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Date Posted: 09:56:00 05/13/13 Mon
Author: Mark Blair
Subject: Trailer repair Joe this is a long one but this will fix it read it all
In reply to: joe 's message, "service trailer brake system" on 07:05:25 05/11/13 Sat

2 bulletins to look at. Check the trailer connector for corrosion, seen a fair number with corrosion on the harness side of the trailer connector. Good luck.

#PIT4900A: Service Trailer Brake Message With DTC(s) C1115 C1116 C1117 And/Or C1118 (Inspect Wiring Near Brake Pedal) - keywords ITBCM towing - (Jun 17, 2010)

Subject: Service Trailer Brake Message With DTC(s) C1115, C1116, C1117, and/or C1118 (Inspect Wiring Near Parking Brake Pedal)

Models: 2009-2011 Chevrolet Avalanche, Suburban, Tahoe

2007-2011 Chevrolet Silverado

2007-2011 GMC Sierra

2009-2011 GMC Sierra Denali, Yukon, Yukon XL

With RPO JL1

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This PI was superseded to update model years. Please discard PIT4900.

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

Condition/Concern: Some customers may comment of a Service Trailer Brake message on the DIC and one or more of the following DTC's: C1115, C1116, C1117, C1118. This concern may be very intermittent and can occur with or without a trailer connected to the truck. During a recent warranty review of returned Trailer Brake Control Switches all switches were found to be NTF (No Trouble Found).

Recommendation/Instructions: Before replacing any parts inspect the wiring to the switch near the parking brake pedal assembly.

Several reports of the wiring being chaffed in this area have been received. Repair any circuits that have been chaffed and reposition/protect the wiring so the concern does not reoccur.

#PIT4595G: Service Trailer Brake Message With DTC C1114 And/Or C1112 - inoperative intermittent program tow way - (Oct 19, 2010)

Subject: Service Trailer Brake Message With DTC C1114 And/Or C1112

Models: 2007-2011 Chevrolet Silverado

2009-2011 Chevrolet Avalanche, Suburban, Tahoe

2007-2011 GMC Sierra

2009-2011 GMC Yukon, Yukon XL

With RPO JL1

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This PI was superseded to combine information from two PIs. Please discard PIT4595F.

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

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

GM is receiving a number of returned Trailer Brake Control Modules (TBCM) and Trailer Brake Relays that are completely functional. The TBCM monitors the voltage of the electric brake wire (dark blue circuit 47) that runs from the trailer brake relay to the 7-pin trailer connector in the bumper. If the voltage on this wire is shorted lower or higher than the designed output voltage of the relay the TBCM will set a DTC.

Recommendation/Instructions: A. Applies to 2007-2008 Silverado and Sierra Models 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. Reprogram the TBCM with the latest cals in TIS2WEB.

• If the voltage is lower, then the updated calibration should still be installed, however additional diagnostics may be needed to correct the concern. Please follow the below information and appropriate SI diagnostics for additional help.

Warranty Information For vehicles repaired under warranty, use:

Labor Operation Description Labor Time

N4896 Trailer Brake Control Module Reprogramming with SPS Use published labor operation time

B. Applies to All Models Listed Please investigate all wiring between the trailer brake relay and the 7-pin trailer connector (including any 5th wheel jumpers/connectors) for damaged wiring/connectors (nicks, cuts, corrosion, pin damage, etc.) and poor quality or non-sealed splices. Even a small amount of water intrusion can wick its way to both the trailer brake relay and the 7-pin trailer connector in the bumper, potentially causing intermittent DTCs.

If a Current DTC is present, please follow the trailer brake service procedures found in SI for the specific DTC.

If only history DTCs are present, follow the diagnostic procedure found in this PI to help with the identification of an intermittent short condition.

IMMEDIATE DIAGNOSIS Check for blown fuses related to the trailer brake system. Disconnect trailer harness (if trailer is with vehicle). Examine vehicle for unsealed splices or damage in vehicle trailer wiring (including 5th wheel wiring harnesses). Examine G401 ground for proper grounding. Clean as required. With the ignition on, use Tech 2 to monitor TBCM Relay Feedback Signal. Monitor signal for 10-15 seconds. Determine the minimum voltage value that occurs. (This voltage varies once per second and always settles down to the minimum.) The minimum voltage should be between 3.2-4.1 V.

• If the voltage is higher or lower - go to Short Investigation section (seen below)

• If Service Trailer Brake Code set - go to Short Investigation section (seen below)

Repeat step 5 with brake applied for 10 seconds. The minimum voltage should be between 3.2-4.1 V.

• If the voltage is higher or lower - go to Short Investigation section (seen below)

• If Service Trailer Brake Code set - go to Short Investigation section (seen below)

Repeat step 5 with vehicle in reverse and with brake applied for 10 seconds. The minimum voltage should be between 3.2-4.1 V.

• If the voltage is higher or lower - go to Short Investigation section

• If Service Trailer Brake Code set - go to Short Investigation section

If damage to wiring harness or splices found in step 3, spray with water and repeat steps 5 - 10. If no issues found in previous steps, follow service procedure for C1112/C1114. SHORT INVESTIGATION Investigate wiring for shorts between trailer brake (electric brake) wire (blue) and any/all of the following trailer wires: Right Turn/Brake, Left Turn/Brake, Running Lights, Back Up, Battery, Ground. Please note that even heat shrunk splices are not necessarily water tight.
Please only use this feature to report severe guidelines violations.

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