Chevrolet Trax: DTC B257A
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 Descriptor
DTC B257A 00
Headlamp Switch Input Signals Correlation Malfunction
Diagnostic Fault Information
Circuit/System Description
For headlamp operation, the body control module (BCM) monitors three signal
circuits from the headlamp
switch. When the headlamp switch is in the AUTO position, the three signal
circuits are unaffected and the
BCM relies on the ambient light sensor input to turn the headlamps and daytime
running lamps ON and OFF.
When the headlamp switch is placed in the OFF position, the headlamp switch
headlamps OFF signal circuit is
grounded, indicating to the BCM that the exterior lamps should be turned OFF.
With the headlamp switch in the
PARK LAMPS position, the headlamp switch park lamps ON signal circuit is
grounded, indicating that the park
lamps have been requested. When the headlamp switch is in the HEADLAMP position,
both the headlamp
switch park lamps ON signal circuit and the headlamp switch headlamps ON signal
circuit are grounded. The
BCM responds by commanding the park lamps and headlamps ON.
Conditions for Running the DTC
Battery voltage must be between 9-16 V.
Conditions for Setting the DTC
- The BCM detects an open/high resistance in the headlamp switch park
lamps ON signal circuit.
- The BCM detects a short to ground in the headlamp switch headlamps ON
signal circuit.
- The BCM detects a short to ground in the headlamp switch headlamps OFF
signal circuit.
Actions Taken When the DTC Sets
- When DTC B257A 00 is present on the headlamp switch headlamps OFF
signal circuit, the low beam
headlamps are always ON in the AUTO position. The headlamp switch operates
in all positions other
than AUTO. The AUTO headlamp defeat is inoperative.
- When DTC B257A 00 is present on the headlamp switch headlamps ON
signal circuit, the low beam
headlamps are always ON. The BCM disregards all headlamp switch inputs.
- When DTC B257A 00 is present on the headlamp switch park lamps ON
signal circuit, the park lamps
and low beam headlamps are inoperative in the PARK and HEAD positions.
Headlamps and park lamps
operate in AUTO position.
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
Headlights/Daytime Running Lights (DRL) Schematics (Encore) ,
Headlights/Daytime Running Lights
(DRL) Schematics (Trax)
Connector End View Reference
WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS -
INDEX - ENCORE WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT
CONNECTOR END VIEWS - INDEX - TRAX
Description and Operation
Exterior 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
- Ignition OFF, all doors closed, all accessories OFF, disconnect the
harness connector at the S30
Headlamp Switch. It may take up to 2 min for all vehicle systems to power
down.
- Test for less than 15 ohms between the ground circuit terminal 6 and
ground.
- Ignition OFF.
- Test for less than 2 ohms in the ground circuit end to end.
- If 2 ohms or greater, repair the open/high resistance in the circuit.
- If less than 2 ohms, repair the open/high resistance in the ground
connection.
- If less than 15 ohms
- Ignition ON.
- Verify the scan tool Automatic Headlamps Disable Switch parameter
is Inactive.
- Ignition OFF, disconnect the X1 harness connector at the K9 Body Control
Module.
- Test for infinite resistance between the signal circuit terminal 5 and
ground.
- If less than infinite resistance, repair the short to ground on the
circuit.
- If infinite resistance, replace the K9 Body Control Module.
- If Inactive
- Install a 3 A fused jumper wire between the signal circuit terminal 5
and the ground circuit terminal 6.
- Verify the scan tool Automatic Headlamps Disable Switch parameter is
Active.
If not Active
- Ignition OFF, disconnect the X1 harness connector at the K9 Body Control
Module, ignition ON.
- Test for less than 1 V between the signal circuit terminal 5 and ground.
- If 1 V or greater, repair the short to voltage on the circuit.
- If less than 1 V
- Test for less than 2 ohms in the signal circuit end to end.
- If 2 ohms or greater, repair the open/high resistance in the circuit.
- If less than 2 ohms, replace the K9 Body Control Module.
- If Active
- Verify the scan tool Park Lamps Switch parameter is Inactive.
- Ignition OFF, disconnect the X1 harness connector at the K9 Body Control
Module.
- Test for infinite resistance between the signal circuit terminal 3 and
ground.
- If less than infinite resistance, repair the short to ground on the
circuit.
- If infinite resistance, replace the K9 Body Control Module.
- If Inactive
- Install a 3 A fused jumper wire between the signal circuit terminal 3
and the ground circuit terminal 6.
- Verify the scan tool Park Lamps Switch parameter is Active.
- Ignition OFF, disconnect the X1 harness connector at the K9 Body Control
Module, ignition ON.
- Test for less than 1 V between the signal circuit terminal 3 and ground.
- If 1 V or greater, repair the short to voltage on the circuit.
- If less than 1 V
- Test for less than 2 ohms in the signal circuit end to end.
- If 2 ohms or greater, repair the open/high resistance in the circuit.
- If less than 2 ohms, replace the K9 Body Control Module.
- If Active
- Verify the scan tool Headlamps On Switch parameter is
Inactive.
- Ignition OFF, disconnect the X1 harness connector at the K9 Body Control
Module.
- Test for infinite resistance between the signal circuit terminal 4 and
ground.
- If less than infinite resistance, repair the short to ground on the
circuit.
- If infinite resistance, replace the K9 Body Control Module.
- If Inactive
- Install a 3 A fused jumper wire between the signal circuit terminal 4
and the ground circuit terminal 6.
- Verify the scan tool Headlamps On Switch parameter is Active.
- Ignition OFF, disconnect the X1 harness connector at the K9 Body Control
Module, ignition ON.
- Test for less than 1 V between the signal circuit terminal 4 and ground.
- If 1 V or greater, repair the short to voltage on the circuit.
- If less than 1 V
- Test for less than 2 ohms in the signal circuit end to end.
- If 2 ohms or greater, repair the open/high resistance in the circuit.
- If less than 2 ohms, replace the K9 Body Control Module.
- If Active
- Test or replace the S30 Headlamp Switch.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the repair.
- Headlamp Switch Replacement (Encore) , Headlamp Switch Replacement (Trax)
- 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
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.
Diagnostic Fault