B3801

DTC B3801

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 Descriptor
DTC B3801
^ Passenger Compartment Lamp Request Circuit

Circuit/System Description

The body control module (BCM) monitors the courtesy lamp switch signal circuit in order to determine when the courtesy/dome lamps should be illuminated. When the BCM senses that the courtesy lamp switch signal circuit is grounded when the switch is activated, the BCM will directly illuminate the courtesy/dome lamps.

Conditions for Running the DTC

The battery voltage must be between 9-16 volts.

Conditions for Setting the DTC

The BCM detects the courtesy lamp switch is active while the IP lamp dimmer switch at the dim position.

Action Taken When the DTC Sets

The courtesy/dome lamps will be inoperative.

Conditions for Clearing the DTC

* This DTC will clear on current status after the condition for setting the fault is corrected.
* A history DTC will clear after 100 consecutive ignition cycles without a fault present.

Reference Information
Schematic Reference

Interior Lights Schematics (Wiring Diagram Index)
Connector End View Reference

Component Connector End Views ()
Description and Operation

Interior Lighting Systems Description and Operation (Interior Lighting Systems Description and Operation)
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 (Control Module References) for Scan Tool Information

Circuit/System Verification

1. Ignition ON, observe the scan tool dimming input parameter. The reading should be between 0.0 and 4.86 volts and change from low to high while the dimmer switch is rotated from bright to dim.

• If the parameter is always high, refer to the dimmer switch circuit test.

2. Observe the scan tool courtesy lamp switch parameter. The reading should change between active and inactive when turning the switch on and off.

• If the parameter is always active, refer to the courtesy lamp switch circuit test.

Circuit/System Testing

Dimmer Switch Circuit Test
1. Ignition OFF, disconnect the harness connector at the IP dimmer switch.
2. Ignition OFF, test for less than 1 ohm of resistance between the low reference circuit terminal 10 and ground.

• If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the BCM.

3. Verify the scan tool dimming input parameter is less than 1.0 volt.

• If greater than the specified range, test the signal circuit terminal 8 for a short to voltage. If the circuit tests normal, replace the BCM.

4. If all circuits test normal replace the IP dimmer switch.

Courtesy Lamp Switch Circuit Test
1. Ignition OFF, disconnect the harness connector at the IP dimmer switch.
2. Ignition ON, verify the scan tool courtesy lamp switch parameter is inactive.

• If not the specified value, test the signal circuit terminal 9 for a short to ground. If the circuit tests normal, replace the BCM.

3. If all circuits test normal replace the IP dimmer switch.

Repair Instructions

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

* Instrument Panel Lamp Dimmer Switch Replacement (Service and Repair)
* Control Module References (Control Module References) for BCM replacement, programming, and setup