Buick Regal: DTC B260B or B260C
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 B260B 02
Left Daytime Running Lamp Relay Control Circuit Short to Ground
DTC B260B 04
Left Daytime Running Lamp Relay Control Circuit Open
DTC B260C 02
Right Daytime Running Lamp Relay Control Circuit Short to Ground
DTC B260C 04
Right Daytime Running Lamp Relay Control Circuit Open
Diagnostic Fault Information
1. Daytime Running Lamps Malfunction
Circuit/System Description
The ambient light sensor is used to monitor outside lighting conditions. The
body control module
(BCM) provides a low reference ground and 5 V reference signal to the ambient
light sensor. Depending
on outside lighting conditions, the ambient light sensor provides a voltage
signal to the BCM that will
vary between 0.2 and 4.9 V. The BCM monitors the ambient light sensor signal
circuit to determine if
outside lighting conditions are correct for either daytime running lamps or
automatic headlamp system
control when the headlamp switch is in the AUTO position. In daylight
conditions, the BCM responds
by applying battery voltage to the left and right daytime running lamp relay
control circuits which
energizes both daytime running lamp relays. With the daytime running lamp relays
energized, the switch contacts close allowing battery voltage to flow to the
daytime running lamp control circuits illuminating
the left and right daytime running lamp.
Conditions for Running the DTC
- Battery voltage must be between 9 - 16 V.
- Engine ON.
- Headlamp switch in AUTO position.
- Ambient light is day.
Conditions for Setting the DTC
DTC B260B 02
The BCM detects a short to ground in the left daytime running lamp relay
control circuit.
DTC B260B 04
The BCM detects an open/high resistance in the left daytime running lamp
relay control circuit.
DTC B260C 02
The BCM detects a short to ground in the right daytime running lamp relay
control circuit.
DTC B260C 04
The BCM detects an open/high resistance in the right daytime running lamp
relay control circuit.
Actions Taken When the DTC Sets
The appropriate daytime running lamp is inoperative.
Conditions for Clearing the DTC
- The condition responsible for setting the DTC no longer exists and the
ignition is cycled.
- A history DTC will clear once 100 consecutive malfunction-free ignition
cycles have occurred.
Reference Information
Schematic Reference
Exterior Lights Wiring Schematics
Connector End View Reference
COMPONENT CONNECTOR END VIEWS - INDEX
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
Circuit/System Testing
DTC B260B
1. Ignition OFF, disconnect the KR42L Daytime Running Lamp Relay - Left.
2. Verify a test lamp illuminates between the B+ circuit terminal 86 and ground.
- If the test lamp does not illuminate
Replace the X50A Fuse Block - Underhood.
- Go to next step: If the test lamp illuminates
3. Verify a test lamp illuminates between the B+ circuit terminal 30 and
ground.
- If the test lamp does not illuminate
Replace the X50A Fuse Block - Underhood.
- Go to next step: If the test lamp illuminates
4. Connect a test lamp between the control circuit terminal 85 and B+,
ignition ON.
5. Verify the test lamp turns ON and OFF when commanding the Left Daytime
Running Lamp ON
and OFF with a scan tool.
- If the test lamp is always OFF
- Ignition OFF, disconnect the X5 harness connector at the K9 Body Control
Module, ignition
ON.
- Test for less than 1 V between the control circuit terminal 21 and
ground.
- If 1 V or greater, repair the short to voltage on the circuit.
- Go to next step: If less than 1 V
- Ignition OFF.
- Test for less than 2 Ω in the control 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.
- If the test lamp is always ON
- Ignition OFF, disconnect the X5 harness connector at the K9 Body Control
Module.
- Test for infinite resistance between the control circuit terminal 21 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 turns ON and OFF
6. Test or replace the KR42L Daytime Running Lamp Relay - Left.
DTC B260C
1. Ignition OFF, disconnect the KR42R Daytime Running Lamp Relay - Right.
2. Verify a test lamp illuminates between the B+ circuit terminal 86 and ground.
- If the test lamp does not illuminate
Replace the X50A Fuse Block - Underhood.
- Go to next step: If the test lamp illuminates
3. Verify a test lamp illuminates between the B+ circuit terminal 30 and
ground.
- If the test lamp does not illuminate
Replace the X50A Fuse Block - Underhood.
- Go to next step: If the test lamp illuminates
4. Connect a test lamp between the control circuit terminal 85 and B+,
ignition ON.
5. Verify the test lamp turns ON and OFF when commanding the Right Daytime
Running Lamp ON
and OFF with a scan tool.
- If the test lamp is always OFF
- Ignition OFF, disconnect the X5 harness connector at the K9 Body Control
Module, ignition
ON.
- Test for less than 1 V between the control circuit terminal 15 and
ground.
- If 1 V or greater, repair the short to voltage on the circuit.
- Go to next step: If less than 1 V
- Ignition OFF.
- Test for less than 2 Ω in the control 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.
- If the test lamp is always ON
- Ignition OFF, disconnect the X5 harness connector at the K9 Body Control
Module.
- Test for infinite resistance between the control circuit terminal 15 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 turns ON and OFF
6. Test or replace the KR42R Daytime Running Lamp Relay - Right.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the repair.
- Relay Replacement (Attached to Wire Harness) Relay Replacement (Within
an Electrical
Center)
- 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:
SPECIFICATIONS
FASTENER SPECIFICATIONS
Single Use Non-Threaded Fasteners/Components
NOTE:
All fasteners/components listed in this table MUST BE DISCARDED and replaced
with NEW after removal.
Application
Power Steering Assist Motor SealSteering Gear BeltSteering Gear Boot Inner ClampSteering Gear Bus
SPECIFICATIONS
FASTENER TIGHTENING TORQUE SPECIFICATIONS
Reusable Threaded Fastener Tightening Specifications
NOTE:
All fasteners listed in this table can be reused after removal.
SCHEMATIC WIRING DIAGRAMS
DRIVER SEAT WIRING SCHEMATICS
Power, Ground, Serial Data and Seat Memory Switch (A45/A44)
Se