Buick Regal: DTC B1395
Diagnostic Instructions
- Perform the Diagnostic System Check - Vehicle prior to using this
diagnostic procedure.
- Review Strategy Based Diagnosis for an overview of the diagnostic
approach.
- Diagnostic Procedure Instructions provides an overview of each
diagnostic category.
DTC Descriptors
DTC B1395 03
Control Module Voltage Reference Output 1 Circuit Low Voltage
DTC B1395 07
Control Module Voltage Reference Output 1 Circuit High Voltage
Diagnostic Fault Information
1. Interior Backlighting Malfunction
Circuit/System Description
The instrument panel dimmer switch is used to increase and decrease the
brightness of the interior
backlighting components. The instrument panel dimmer switch provides a voltage
signal to the body
control module (BCM) that will increase as the brightness of the lights are
increased and decrease as the
brightness of the lights are decreased. The BCM provides a low reference,
signal, and B+ voltage
reference to the instrument panel dimmer switch. When the instrument panel
dimmer switch is placed in
the desired position, the dimmed voltage setting is applied from the instrument
panel dimmer switch
through the instrument panel dimmer switch signal circuit to the BCM. The BCM
interprets the signal
and applies a pulse width modulated voltage through the LED dimming 1 and
dimming 2 control circuits
illuminating the interior backlighting to the requested level of brightness.
Conditions for Running the DTC
- Battery voltage must be between 9-16 V.
- Park Lamps ON.
Conditions for Setting the DTC
DTC B1395 03
- The BCM detects a short to ground in the instrument panel dimmer switch
B+ reference circuit.
- The BCM detects a short to ground in the instrument panel dimmer switch
signal circuit.
DTC B1395 07
- The BCM detects a short to voltage in the instrument panel dimmer switch
B+ reference circuit.
- The BCM detects a short to voltage in the instrument panel dimmer switch
signal circuit.
Actions Taken When the DTC Sets
The BCM will not dim any interior backlighting. All interior backlighting
will default to the FULL
bright.
Conditions for Clearing the DTC
- The condition responsible for setting the DTC no longer exists.
- A history DTC will clear once 100 consecutive malfunction-free ignition
cycles have occurred.
Reference Information
Schematic Reference
Interior Lights Dimming Wiring Schematics
Connector End View Reference
COMPONENT CONNECTOR END VIEWS - INDEX
Description and Operation
Interior Lighting Systems Description and Operation
Electrical Information Reference
- Circuit Testing
- Connector Repairs
- Testing for Intermittent Conditions and Poor Connections
- Wiring Repairs
Scan Tool Reference
Control Module References for scan tool information.
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the S30 Instrument Panel
Dimmer Switch,
ignition ON.
2. Test for B+ between the B+ reference circuit terminal 12 and ground.
- Ignition OFF, disconnect the X1 harness connector at the K9 Body Control
Module.
- Test for infinite resistance between the B+ reference circuit terminal
12 and ground.
- If less than infinite resistance, repair the short to ground on the
circuit.
- Go to next step: If infinite resistance
- Test for less than 2 Ω in the B+ reference circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, replace the K9 Body Control Module.
3. Verify a test lamp does not illuminate between B+ and the signal circuit
terminal 11.
- If the test lamp illuminates
- Ignition OFF, disconnect the X2 harness connector at the K9 Body Control
Module.
- Test for infinite resistance between the signal circuit terminal 11 and
ground.
- If less than infinite resistance, repair the short to ground on the
circuit.
- If infinite resistance, replace the K9 Body Control Module.
- Go to next step: If the test lamp does not illuminate
4. Test for B+ between the B+ reference circuit terminal 12 and the signal
circuit terminal 11.
- Ignition OFF, disconnect the X2 harness connector at the K9 Body Control
Module, ignition
ON.
- Test for less than 1 V between the signal circuit terminal 11 and
ground.
- If 1 V or greater, repair the short to voltage on the circuit.
- Go to next step: If less than 1 V
- Test for less than 2 Ω in the signal circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, replace the K9 Body Control Module.
5. Test for B+ between the B+ reference circuit terminal 12 and the low
reference circuit terminal 7.
- Ignition OFF, disconnect the X1 harness connector at the K9 Body Control
Module, ignition
ON.
- Test for less than 1 V between the low reference circuit terminal 7 and
ground.
- If 1 V or greater, repair the short to voltage on the circuit.
- Go to next step: If less than 1 V
- Test for less than 2 Ω in the low reference circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, replace the K9 Body Control Module.
6. Verify a test lamp does not illuminate between the B+ reference circuit
terminal 12 and ground.
- If the test lamp illuminates
- Ignition OFF, disconnect the X1 harness connector at the K9 Body Control
Module, ignition
ON.
- Test for less than 1 V between the B+ reference circuit terminal 12 and
ground.
- If 1 V or greater, repair the short to voltage on the circuit.
- If less than 1 V, replace the K9 Body Control Module.
- Go to next step: If the test lamp does not illuminate
7. Test or replace the S30 Instrument Panel Dimmer Switch.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the repair.
- Headlamp Switch Replacement
- Control Module References for BCM replacement, programming, and setup
READ NEXT:
Diagnostic Instructions
Perform the Diagnostic System Check - Vehicle prior to using this
diagnostic procedure.
Review Strategy Based Diagnosis for an overview of the diagnostic
approach.
Diag
Diagnostic Instructions
Perform the Diagnostic System Check - Vehicle prior to using this
diagnostic procedure.
Review Strategy Based Diagnosis for an overview of the diagnostic
approach.
Diag
Diagnostic Instructions
Perform the Diagnostic System Check - Vehicle prior to using this
diagnostic procedure.
Review Strategy Based Diagnosis for an overview of the diagnostic
approach.
Diag
SEE MORE:
Diagnostic Instructions
Perform the Diagnostic System Check - Vehicle prior to using this
diagnostic procedure.
Review Strategy Based Diagnosis for an overview of the diagnostic
approach.
Diagnostic Procedure Instructions provides an overview of each
diagnostic category.
DTC Descriptors
D
Special Tools
EL-35616 Terminal Test Probe Kit
For equivalent regional tools, refer to Special Tools.
When the condition is not currently present, but is indicated in DTC history,
the cause may be
intermittent. An intermittent may also be the cause when there is a customer
complaint, but the sympt