B3886

DTC B3885 or B3886

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.

DTC Descriptors
DTC B3885 02
- Trailer Left Tail Lamp Circuit Short to Ground

DTC B3885 04
- Trailer Left Tail Lamp Circuit Open

DTC B3886 02
- Trailer Right Tail Lamp Circuit Short to Ground

DTC B3886 04
- Trailer Right Tail Lamp Circuit Open

Diagnostic Fault Information





Circuit/System Description

The trailer brake control module will receive a serial data message from the body control module (BCM) indicating that the vehicle park lamps have been activated. The trailer brake control module will then apply system voltage to the trailer tail lamps through their respective voltage supply circuits.

Conditions for Running the DTC

When the parking lamps are turned on.

Conditions for Setting the DTC

B3885 02 or B3886 02

The trailer brake control module detects a short to ground on the appropriate tail lamp control circuit.

B3885 04 or B3886 04

The trailer brake control module detects an open/high resistance in the appropriate tail lamp control circuit.

Action Taken When the DTC Sets

The appropriate trailer tail lamp will be inoperative.

Conditions for Clearing the DTC

* The DTC will be current for as long as the fault is present.
* When the fault is no longer present, the DTC will be a history DTC.
* A history DTC will clear after 40 ignition cycles.

Reference Information
Schematic Reference

Trailer Connector/Provision Schematics (Trailer Connector/Provision Schematics)
Connector End View Reference

Component Connector End Views (Connector End Views By Name)
Description and Operation

Exterior Lighting Systems Description and Operation (Exterior Lighting Systems)
Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information

Circuit/System Verification

Ignition ON, observe the function of the left trailer tail lamp and the right trailer tail lamp while commanding the Left Trailer Tail Lamp and the Right Trailer Tail Lamp ON and OFF with a scan tool. The left trailer tail lamp and the right trailer tail lamp should turn ON and OFF while changing between the commanded states.

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 listed below and ground:

* Right trailer park lamp control terminal 16
* Left trailer park lamp control terminal 4

• If 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 terminals listed below:

* Control terminal 16 at the K68 trailer lighting control module and control terminal 5 at the X88 trailer connector.
* Control terminal 4 at the K68 trailer lighting control module and control terminal 7 at the X88 trailer connector.

• If 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 (Verification Tests) after completing the diagnostic procedure.

Control Module References (Programming and Relearning) for trailer brake control module replacement, programming and setup