Diagnostic Instructions

DTC Descriptors

DTC B1395 03: Device Voltage Reference Output 1 Circuit Below Threshold

DTC B1395 07: Device Voltage Reference Output 1 Circuit Above Threshold

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
BCM Supply Voltage	B1395 03, B3600 03	B1395 03, B3600 03	--	--
I/P Dimming Voltage Reference	B1395 03, B3600 03	B3600 03	--	B1395 07
Stop Lamp Switch Signal	B1395 03, B3600 03	2	2	--
Instrument Panel Lamps Dimmer Switch Signal	B3600 03	B3600 03	1	--
1. Interior Backlighting Malfunction 2. Stop Lamps Malfunction

Circuit/System Description

The body control module (BCM) supplies a voltage reference through the instrument panel (I/P) dimming voltage reference circuit to the interior lamp dimmer switch, which is part of the headlamp switch. When the dimmer switch is placed in a desired brightness position, reference voltage is applied through the dimmer switch rheostat and the I/P lamps dimmer switch signal circuit to the BCM. The BCM interprets this voltage signal, then applies a pulse width modulated (PWM) voltage through the I/P lamps supply voltage circuit and the LED dimming supply circuit to all related interior lamps, illuminating them to the desired level of brightness.

Conditions for Running the DTC

Ignition ON.

Conditions for Setting the DTC

B1395 03

The BCM detects a voltage that is lower than 9 volts on the I/P dimming voltage reference circuit.

B1395 07

The BCM detects a voltage that is greater than 14 volts on I/P dimming voltage reference circuit.

Action Taken When the DTC Sets

The I/P lamps are not illuminated.

Conditions for Clearing the DTC

Reference Information

Schematic Reference

Interior Lights Dimming Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Interior Lighting Systems Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Ignition ON, cover the ambient light sensor, vary the interior lamp dimming switch from dim to full bright. The I/P lamps should dim and then become full bright.

Circuit/System Testing

1. Ignition OFF, disconnect the X3 harness connector at the BCM
2. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal 3 and ground.

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

3. Ignition OFF, connect the X3 harness connector at the BCM and disconnect the harness connector at the headlamp switch.
4. Ignition ON, verify that a test lamp illuminates between the B+ reference circuit terminal 15 and ground.

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

5. Ignition OFF, disconnect the harness connector at the stop lamp switch.
6. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal C and ground.

⇒	If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.

7. Install a 3A fused jumper wire between the signal circuit terminal D and the B+ circuit terminal C. Verify that the scan tool Stop Lamp Switch Status parameter is 1023 counts.

⇒	If not the specified value, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.

8. If all circuits test normal, replace the headlamp switch.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.