Lighting and Horns System
DTC B1395
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions provides an overview of the diagnostic category.
DTC Descriptors
DTC B1395 03
- Voltage Below Threshold
DTC B1395 07
- Voltage Above Threshold
Diagnostic Fault Information
Circuit/System Description
The instrument panel (I/P) dimmer switch is used to increase and decrease the brightness of the interior backlighting components. The I/P dimmer switch provides a voltage signal that will increase as the brightness of the light are increased and decrease as the brightness of the lights are decreased. The body control module (BCM) provides a low reference signal and a B+ voltage reference to the I/P dimmer switch. When the I/P dimmer switch is placed in the desired position, the dimmed voltage setting is applied from the I/P dimmer switch through the I/P dimmer switch signal circuit to the BCM. The BCM interprets the signal and applies the dimmed voltage to the I/P lamps supply voltage circuit and the interior backlighting components dim to the requested level. For more detailed information concerning interior lamp operation refer to Interior Lighting Systems Description and Operation.
Conditions for Running the DTC
Battery voltage must be between 9-16 volts.
Conditions for Setting the DTC
B1395 03
DTC B1395 03 will set for the following conditions:
* The BCM detects a short to ground in the I/P dimming voltage reference circuit.
* The BCM detects a short to ground in the I/P dimmer switch signal circuit.
* The BCM detects a short to ground or an open/high resistance in the BCM 1 fuse B+ circuit.
B1395 07
The DTC will set when the BCM detects a short to voltage in the I/P dimming voltage reference circuit or the vehicles system voltage exceeds the normal operating range of 16 volts.
Actions Taken When the DTC Sets
* The I/P dimmer switch will not operate.
* The I/P dimming lamps will not illuminate.
Conditions for Clearing the DTC
* The condition responsible for setting the DTC no longer exists.
* You issue a scan tool CLEAR DTCs command.
* A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.
Circuit/System Verification
1. Ignition ON, observe the scan tool Dimming Control Reference voltage. The reading should display battery voltage.
• If less than the specified range, refer to I/P Dimming Control Malfunction.
• If within the specified range, refer to I/P Dimmer Switch Malfunction.
Circuit/System Testing
I/P Dimmer Switch Malfunction
1. Ignition OFF, disconnect the harness connector at the I/P Dimmer switch.
2. Ignition OFF, verify that a test lamp illuminates between B+ and the ground circuit terminal 10.
• If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
3. Ignition ON, test for B+ between the I/P dimming voltage reference circuit terminal 5 and ground.
• If less than the specified range, test the voltage reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
• If greater than the specified range, test the voltage reference circuit for a short to voltage. If the circuit tests normal, replace the BCM.
4. Install a 3-A fused jumper wire between the signal circuit terminal 9 and the B+ voltage reference circuit terminal 5. Verify the scan tool dimming control signal parameter is greater than 2.5 volts.
• If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
5. If all circuits test normal, test or replace the I/P dimmer switch.
I/P Dimming Control Malfunction
1. Ignition OFF, disconnect the C3 harness connector at the BCM.
2. Ignition ON, verify that a test lamp illuminates between the BCM 1 fuse voltage supply circuit terminal 3 and ground.
• If the test lamp does not illuminate, test the voltage supply circuit for a short to ground or an open/high resistance.
3. If all circuit tests normal, replace the BCM.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests
* Instrument Panel Dimmer Switch Replacement (Left Hand Drive) Instrument Panel Dimmer Switch Replacement (Right Hand Drive)
* Control Module References for BCM replacement, setup, and programming. Programming and Relearning