C1116
DTC C1116
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptor
DTC C1116
- Manual Trailer Brake Apply Request Signal 1
Diagnostic Fault Information
Circuit/System Description
The primary manual apply switch circuit diagnostic monitors for circuit faults on the primary manual apply switch input to the trailer brake control module (TBCM).
This DTC will also be set as current DTC when a fault is detected in 5-volt reference voltage or in TBCM ground circuit.
Conditions for Running the DTC
* The system voltage is in the range of 9.5-17 volts.
* The module is powered up and completes initialization.
Conditions for Setting the DTC
DTC C1116 will set as current DTC, if one of the following conditions is true:
* The TBCM detects an open in the manual apply signal circuit.
* The TBCM detects short to ground in the manual apply signal circuit.
* The TBCM detects short to battery positive in the manual apply signal circuit.
Action Taken When the DTC Sets
* The trailer brake control will be disabled for the remainder of the ignition cycle.
* The Service Trailer Brake System will be displayed on the Driver Information Center (DIC).
Condition for Clearing the MIL/DTC
* When the condition for the DTC is no longer present.
* The TBCM automatically clears the history DTC when a current DTC is not detected in 40 consecutive drive cycles.
Diagnostic Aids
If there are any DTCs set for GMLAN communication such as U0100, U0121, U0140, or U2099, diagnose them first before to resolve DTCs described in this section.
When the manual apply switch 5-volt reference circuit or TBCM ground is open circuit, in addition to setting DTC C1116, DTC C1117 and C1118 may also be set as current DTC. In this case, diagnose the apply switch 5-volt reference circuit or TBCM ground first for open circuit fault before to diagnosing DTC C1116.
If there is an aftermarket trailer brake controller, the ITBC must be disconnected. Do not power both ITBC and aftermarket controllers to control the trailer brakes at the same time.
Circuit/System Verification
1. Ignition ON, observe the scan tool brake controls Primary Manual Apply parameter. The reading should be between 0-100 percent and change with brake pedal input.
2. Ignition ON, observe the scan tool brake controls Redundant Manual Apply parameter. The reading should be between 0-100 percent and change with brake pedal input.
Circuit/System Testing
Important: All electrical components and accessories must be turned OFF and allowed to power down.
1. Ignition OFF, disconnect the harness connector at the trailer brake controller switch panel.
2. Test for less than 5 ohms of resistance between the ground circuit terminal 8 and ground.
* If greater than the specified range, test the ground circuit for an open/high resistance. If the circuit tests normal, replace the TBCM.
3. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 3 and ground.
* If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the TBCM.
* If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the TBCM.
4. Install a 3A fused jumper wire between the signal circuit terminal 4 and the 5-volt reference circuit terminal 3. Verify the scan tool Manual Apply Switch is greater than 90 percent.
* If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the TBCM.
5. If all circuits test normal, test or replace the trailer brake controller switch panel.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests
* Refer to to Programming and Relearning for programming and setup procedures. Programming and Relearning
* Trailer Brake Control Module Replacement