2010 Cadillac Truck SRX AWD V6-3.0L Page 730
Circuit/System Testing
1. Ignition OFF, disconnect the X1 harness connector at the K68 trailer lighting control module.
2. Test for infinite resistance between the control circuit terminal 8 and ground.
瀚慖f less than the specified value, test the control circuit for a short to ground. If the circuit tests normal, replace the X88 trailer connector.
3. Test for less than 1 ohm between the control circuit terminal 8 at the K68 trailer lighting control module and control circuit terminal 2 at the
X88 trailer connector.
瀚慖f greater than the specified range, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal,
replace the X88 trailer connector.
4. If all the circuits test normal, replace the K68 trailer lighting control module.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
Control Module References (See: Testing and Inspection/Programming and Relearning) for the trailer brake control module replacement,
programming and setup
B3890
DTC B3890
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptors
DTC B3890 02
- Trailer Backup Lamps Circuit Short to Ground
DTC B3890 04
- Trailer Backup Lamps Circuit Open
Diagnostic Fault Information
Circuit/System Description
The trailer brake control module will receive a serial data message from the BCM indicating that the vehicle backup lamps have been activated. The
trailer brake control module will then apply system voltage to the trailer backup lamps through their respective voltage supply circuits.
Conditions for Running the DTC
When the trailer backup lamps are turned on.
Conditions for Setting the DTC
B3890 02
The trailer brake control module detects a short to ground on the trailer backup lamp control circuit.
B3890 04
The trailer brake control module detects an open/ high resistance on the trailer backup lamp control circuit.
