B3838

DTC B3838

Diagnostic Instructions

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

DTC Descriptor
DTC B3838
- Park Lamp Relay Control Circuit

Circuit/System Description

The body control module (BCM) turns on the PARK/LAMP relay when the ambient light sensor senses a dark condition or the park lamps are requested ON. Battery positive voltage is supplied to the PARK/LAMP relay at all times. The BCM grounds the PARK/LAMP relay control circuit in order to activate the relay.

Conditions for Running the DTC

* The ignition switch is in the ON position.
* The ambient light sensor senses a dark condition (automatic lamp control (ALC) park lamps ON).

Conditions for Setting the DTC

* The BCM detects a short to voltage, short to ground, open, or high resistance in the park lamp relay control circuit.
* The condition above must be present for more than 0.3 second.

Action Taken When the DTC Sets

The park lamps will not operate or will remain always ON.

Conditions for Clearing the DTC

* The conditions for setting the DTC are no longer present.
* A history DTC clears after 100 malfunction-free ignition cycles.

Reference Information
Schematic Reference

Exterior Lights Schematics (Exterior Lights Schematics)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

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

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

Scan Tool Reference

Control Module References (Programming and Relearning) for Scan Tool Information

Circuit/System Testing

1. Ignition OFF, disconnect the PARK/LAMP relay.
2. Ignition ON, verify that a test lamp illuminates between the B+ circuit of the PARK/LAMP relay and ground.

• If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.

3. Connect a test lamp between the B+ circuit of the PARK/LAMP relay and the control circuit of the PARK/LAMP relay.
4. Command the backup lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

• If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM.

• If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.

5. If all circuits test normal, replace the PARK/LAMP relay.

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Control Module References (Programming and Relearning)
* Relay Replacement (Attached to Wire Harness) (Relay Replacement (Attached to Wire Harness))Relay Replacement (Within an Electrical Center) (Relay Replacement (Within an Electrical Center))