Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptor
DTC C0870 00: Device Voltage Reference Output 1 CircuitDTC C1112 00: Trailer Brake Control Relay Low Control Circuit
DTC C1113 01: Trailer Brake Control Relay High Control Circuit Short to Battery
DTC C1114 00: Trailer Brake Control Solenoids Control Circuit
DTC C1119 00: Trailer Brake Control Sensitivity Switch Circuit
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
B+ | C1112 00 | C1112 00 | -- | -- |
Relay Feedback Signal | C1119 00 | C1119 00 | C1119 00 | -- |
Solid State Relay Enable Control | C1112 00 | C1112 00 | C1113 01 | -- |
Trailer Brake Output Supply Voltage Control | C1114 00 | C1114 00 | C1113 01,C1114 00 | -- |
Intergrated Trailer Brake Relay Control Active Low Control | C1112 00 | C1112 00 | C1112 00 | -- |
Ground | -- | C1112 | -- | -- |
Circuit/System Description
The trailer brake control relay recieves inputs from the trailer brake control module(TBCM), these inputs are used to determine the amount of voltage the relay will supply to the trailer brakes
Conditions for Running the DTC
| • | Ignition ON. |
| • | Battery voltage is 9.5 - 17 volts. |
| • | The module is powered up and completes initialization. |
Conditions for Setting the DTC
C0870 00
The TBCM circuit reference voltage for the trailer brake control relay is below 4.8 volts or above 5.2 volts.
C1112 00
| • | The TBCM detects a short to ground, open or a short to voltage on the integrated trailer brake relay control active low circuit. |
| • | The TBCM detects an open in the battery positive voltage circuit to the trailer brake control relay. |
| • | The TBCM detects an open in the ground circuit to the trailer brake control relay. |
| • | The TBCM detects a short to ground or open in the solid state relay enable circuit. |
C1113 01
| • | The TBCM detects a short to voltage in the solid state relay enable circuit. |
| • | The TBCM detects a short to voltage in the trailer brake output supply voltage control circuit. |
C1114 00
The TBCM detects a short to ground, open or a short to voltage on the solid state relay enable circuit.
C1119 00
The TBCM detects a short to ground, open or a short to voltage on the relay feedback circuit.
Action Taken When the DTC Sets
| • | The trailer brake control will be disabled for the remainder of the ignition cycle. |
| • | The driver information center (DIC) will display Service Trailer Brake System. |
Condition for Clearing the DTC
| • | The condition for the DTC is no longer present. |
| • | The TBCM clears the history DTC when a current DTC is not detected in 40 consecutive drive cycles. |
Reference Information
Schematic Reference
Trailer Brake Control Schematics
Connector End View Reference
Description and Operation
Trailer Brake Controls Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
Ignition ON, observe the scan tool trailer brake controls user gain parameter. The reading should be between 0-100 percent, and change with operating the gain switch up or gain switch down.
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the solid state relay.
- Test for less than 5 ohms of resistance between the ground circuit terminal B and ground.
- Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal F and ground.
- Ignition ON, test for 9 - 11 volts between the control circuit terminal E and ground.
- Ignition ON, test for 3.4 - 3.8 volts between the control circuit terminal C and ground.
- Ignition ON, test for 3.4 - 3.8 volts between the control circuit terminal A and ground.
- Ignition ON, test for less than 1 volt between the control circuit terminal D and ground.
- Ignition OFF, test for 420 K - 520 K ohms between the control circuit terminal D and ground.
- If all circuits test normal, replace the trailer brake solid state relay.
| ⇒ | If greater than the specified range, test the ground circuit for an open/high resistance. |
| ⇒ | If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the STUD 2 fuse is open, replace the trailer brake control relay. |
| ⇒ | If less than the specified range, test the control 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 control circuit for a short to voltage. If the circuit tests normal, replace the TBCM. |
| ⇒ | If less than the specified range, test the control 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 control circuit for a short to voltage. If the circuit tests normal, replace the TBCM. |
| ⇒ | If less than the specified range, test the control 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 control circuit for a short to voltage. If the circuit tests normal, replace the TBCM. |
| ⇒ | If greater than the specified range, test the control circuit for a short to voltage. If the circuit tests normal, replace the TBCM. |
| ⇒ | If less than the specified range, test the control circuit for a short to ground. If the circuit tests normal, replace the TBCM. |
| ⇒ | If greater than the specified range, test the control circuit for a or an open/high resistance. If the circuit tests normal, replace the TBCM. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for TBCM replacement, setup, and programming |
