Buick Regal: DTC B3715 or B3875
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 B3715
Windshield Wiper Relay Circuit
DTC B3875
Windshield Wiper High Speed Relay Circuit
For symptom byte information, refer to Symptom Byte List.
Diagnostic Fault Information
Circuit/System Description
The windshield wiper motor is controlled by the body control module (BCM)
through the windshield wiper relay
and the windshield wiper speed control relay. When low speed windshield wiper
operation is requested, the BCM
will apply voltage to the windshield wiper relay control circuit. This will
cause the contacts in the windshield wiper
relay to close and apply B+ to the windshield wiper motor through the windshield
wiper low speed control circuit,
enabling low speed wiper operation. When high speed windshield wiper operation
is requested, the BCM continues
to apply voltage to the windshield wiper relay control circuit and also applies
ground to the windshield wiper speed
control relay control circuit. This will cause the contacts in the windshield
wiper speed control relay to close and
apply B+ to the windshield wiper motor through the windshield wiper high speed
control circuit, enabling high
speed wiper operation. When the windshield wiper request is no longer present.
the BCM uses an algorithm to keep
relays engaged to keep wiper motor going at the last required speed until it
sees that the motor is in the park position
and then it will remove the necessary control drivers to stop the motor.
Conditions for Running the DTC
- The DTC runs only when a wiper output is actively being requested by the
BCM.
- The system voltage is between 9 - 16 V.
Conditions for Setting the DTC
B3715 01
A short to voltage is detected in the windshield wiper relay control circuit.
B3715 02
A short to ground is detected in the windshield wiper relay control circuit.
B3715 04
An open or high resistance is detected in the windshield wiper relay control
circuit.
B3875 01
A short to voltage is detected in the windshield wiper high speed relay
control circuit.
B3875 02
A short to ground is detected in the windshield wiper high speed relay
control circuit.
B3875 04
An open or high resistance is detected in the windshield wiper high speed
relay control circuit.
Action Taken When the DTC Sets
The BCM will not activate the wiper output.
Conditions for Clearing the DTC
- A current DTC will clear when the condition for setting the fault is no
longer present.
- A history DTC will clear after 50 consecutive ignition cycles without a
fault present.
Reference Information
Schematic Reference
Wiper/Washer Wiring Schematics
Connector End View Reference
COMPONENT CONNECTOR END VIEWS - INDEX
Description and Operation
Wiper/Washer System 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
DTC B3715
1. Ignition OFF and all vehicle systems OFF, disconnect the KR12B Windshield
Wiper Relay. It may take up to
2 min for all vehicle systems to power down.
2. Test for less than 10 Ω between the ground circuit terminal 85 and ground.
- Ignition OFF.
- Test for less than 2 Ω in the ground circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, repair the open/high resistance in the ground
connection.
- Go to next step: If less than 10 Ω
3. Ignition ON. Connect a test lamp between the control circuit terminal 86
and the ground circuit terminal 85.
4. Verify the test lamp turns ON and OFF when commanding the Windshield Wiper
Motor Relay On and Off
with a scan tool.
- If the test lamp is always OFF
- Ignition OFF, remove the test lamp, and disconnect the X4 harness
connector at the K9 Body Control
Module.
- Test for infinite resistance between the control circuit 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 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, remove the test lamp, and disconnect the X4 harness
connector at the K9 Body Control
Module, ignition ON.
- Test for less than 1 V between the control circuit 16 X4 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 turns ON and OFF
5. Test or replace the KR12B Windshield Wiper Relay.
DTC B3875
1. Ignition OFF and all vehicle systems OFF, disconnect the KR12C Windshield
Wiper Speed Control Relay.
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. Ignition ON. Connect a test lamp between the control circuit terminal 85
and the B+ circuit terminal 86.
4. Verify the test lamp turns ON and OFF when commanding the Windshield Wiper
Motor Relay High and Stop
with a scan tool.
- If the test lamp is always OFF
- Ignition OFF, remove the test lamp, disconnect the X5 harness connector
at the K9 Body Control
Module, ignition ON.
- Test for less than 1 V between the control circuit terminal 24 X5 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, remove the test lamp, disconnect the X5 harness connector
at the K9 Body Control
Module.
- Test for infinite resistance between the control circuit terminal 24 X5
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
5. Test or replace the KR12C Windshield Wiper Speed Control Relay.
Component Testing
Relay Test
1. Ignition OFF, disconnect the appropriate relay.
2. Test for 60 - 200 Ω between terminals 85 and 86.
- If less than 60 or greater than 200
Replace the relay.
- Go to next step: If between 60 - 200 Ω
3. Test for infinite resistance between the terminals listed below:
- 30 and 86
- 30 and 87
- 30 and 85
- 85 and 87
- If less than infinite resistance
Replace the relay.
- Go to next step: If infinite resistance
4. Test for less than 5 Ω between terminals 30 and 87A.
Replace the relay.
- Go to next step: If less than 5 Ω
5. Install a 10 A fused jumper wire between relay terminal 85 and 12 V.
Install a jumper wire between relay
terminal 86 and ground.
6. Test for less than 5 Ω between terminals 30 and 87.
Replace the relay.
- Go to next step: If less than 5 Ω
7. All OK
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic
procedure.
- Relay Replacement (Attached to Wire Harness) Relay Replacement (Within
an Electrical Center)
- Control Module References for BCM replacement, setup, and programming
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
NOTE: The following steps must be completed before using the symptom
tables:
1. Perform Diagnostic System Check - Vehicle , in order to verify that all of
the following conditions are true:
No DTC
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 Descriptor
DT
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