Buick Regal: Rear Wiper System Malfunction
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 Information
1. Rear Wiper Inoperative.
2. Rear Wiper Always ON.
Circuit/System Description
The rear wiper motor is controlled by the body control module (BCM) via a
printed circuit board (PCB) relay. The
BCM will respond by commanding the specific rear wiper function based on an
input from the rear wiper switch,
which is part of the windshield wiper/washer switch. The rear wiper switch uses
a resistor ladder to determine low
speed, intermittent, and rear washer operation. A constant B+ and ground are
supplied to the rear wiper motor. When
the rear wiper switch is placed in the low speed, intermittent, or rear washer
position, the voltage is pulled down
through a different resistor in the resistor ladder, reducing the voltage seen
at the BCM.
The BCM monitors the liftgate ajar signal circuit, and the BCM will disable the
function of the rear wiper motor if
the liftgate or liftglass is ajar or open
Diagnostic Aids
If the vehicle is a HATCHBACK, The rear liftgate must be closed in order for
the rear wiper to work. The liftgate
ajar switch signal circuit provides information to the rear window wiper module
about the status of the liftgate. If the
liftgate or liftglass is open the rear wiper operation is not performed.
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 Verification
1. Ignition ON.
2. Verify the scan tool Rear Closure Ajar Switch parameter changes between
Inactive and Active when opening
and closing the liftgate.
- If the parameter does not change
Refer to Rear Hatch/Gate Ajar Indicator Malfunction
(With TB5) Rear Hatch/Gate Ajar Indicator
Malfunction (Without TB5)
- Go to next step: If the parameter changes
3. Verify that DTC B370B is not set.
Refer to DTC B370B
- Go to next step: If DTC B370B is not set
4. Verify the scan tool Rear Wiper Switch parameter
changes between Off and On when turning the rear wipers
ON and OFF.
- If the parameter does not change
Refer to Circuit/System Testing - Rear Wiper/Washer
Switch Malfunction.
- Go to next step: If the parameter changes
5. Verify the Rear Wiper Motor turns On when commanding
the Rear Wiper Active with a scan tool.
- If the Rear Wiper Motor does not turn ON
Refer to Circuit/System Testing - Rear Wiper Motor
Malfunction
- Go to next step: If the Rear Wiper Motor turns ON
6. All OK.
Circuit/System Testing
Rear Wiper/Washer Switch Malfunction
1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector
at the S82 Windshield
Wiper/Washer Switch. It may take up to 11 min for all vehicle systems to power
down.
2. Test for less than 10 Ω between the low reference circuit terminal 1 and
ground.
- Ignition OFF.
- 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.
- Go to next step: If less than 10 Ω
3. Ignition ON.
4. Test for greater than 8 V between the signal circuit terminal 5 and ground.
- Ignition OFF, disconnect the harness connector at the K9 Body Control
Module.
- Test for infinite resistance between the signal 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 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.
Go to next step: If 8 V or greater
5. Ignition OFF, disconnect the X2 harness connector at the K9 Body Control
Module, ignition ON.
6. Test for less than 1 V between the S82 Windshield Wiper/Washer Switch signal
circuit terminal 5 and ground.
Repair the short to voltage on the circuit.
- Go to next step: If less than 1 V
7. Test or replace the S82 Windshield Wiper/Washer Switch.
Rear Wiper Motor Malfunction
1. Ignition OFF, and all vehicle systems OFF. Disconnect the X1 harness
connector at the X50A Fuse Block -
Underhood. It may take up to 2 min for all vehicle systems to power down.
2. Test for less than 10 Ω between the X50A Fuse Block - Underhood ground
circuit terminal 53 and ground.
- 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. Disconnect the harness connector at the M45 Rear Wiper Motor and connect
the X1 harness connector at the
X50A Fuse Block - Underhood. It may take up to 2 min for all vehicle systems to
power down.
4. Test for less than 10 Ω between the ground circuit terminal B and ground.
- 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
5. Ignition ON.
6. Verify a test lamp illuminates between the ignition circuit terminal C and
ground.
- If the test lamp does not illuminate and the circuit fuse is good
- Ignition OFF.
- Test for less than 2 Ω in the ignition circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, refer to Retained Accessory Power Malfunction.
- If the test lamp does not illuminate and the circuit fuse is open
- Ignition OFF, disconnect the M45 Rear Wiper Motor.
- Test for infinite resistance between the ignition circuit and ground.
- If less than infinite resistance, repair the short to ground on the
circuit.
- If infinite resistance, replace the M45 Rear Wiper Motor.
- Go to next step: If the test lamp illuminates
7. Verify a test lamp illuminates between the B+ circuit terminal A and the
ground circuit terminal B.
- If the test lamp does not illuminate
- Ignition OFF, remove the test lamp. Disconnect the X2 harness connector
at the X50A Fuse Block -
Underhood.
- 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 X50A Fuse Block - Underhood.
- Go to next step: If the test lamp illuminates
8. Connect a test lamp between the control circuit terminal C and the ground
circuit terminal A.
9. Verify the test lamp does NOT turn ON and OFF when commanding the Rear Wiper
On and Off with a scan
tool.
- If the test lamp turns ON and OFF
Test or replace the M45 Rear Wiper Motor.
- Go to next step: If the test lamp does NOT turn ON and OFF
10. Ignition OFF, connect the harness connector at the M45 Rear Wiper Motor,
ignition ON.
11. Verify the M45 Rear Wiper Motor is NOT activated.
- If the M45 Rear Wiper Motor is activated
- Ignition OFF, disconnect the harness connector at the M45 Rear Wiper
Motor, ignition ON.
- Test for less than 1 V between the control circuit terminal C and
ground.
- If 1 V or greater, repair the short to voltage on the circuit.
- If less than 1 V, replace the M45 Rear Wiper Motor.
- Go to next step: If the M45 Rear Wiper Motor is not activated
12. Connect a 20 A fused jumper wire between the circuit terminal 19 X2 and
B+.
13. Verify the M45 Rear Wiper Motor activates.
- If the M45 Rear Wiper Motor does not activate
- Ignition OFF, remove the jumper wire, disconnect the harness connector
at the M45 Rear Wiper Motor,
ignition ON.
- 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 M45 Rear Wiper Motor.
- Go to next step: If the M45 Rear Wiper Motor activates
14. Ignition OFF, connect the X2 harness connector at the X50A Fuse Block -
Underhood. Disconnect the X4
harness connector at the K9 Body Control Module, ignition ON.
15. Verify the M45 Rear Wiper Motor is not activated.
- If the M45 Rear Wiper Motor is activated
- Ignition OFF, disconnect the X2 harness connector at the X50A Fuse Block
- Underhood, ignition ON.
- Test for less than 1 V between the control circuit terminal 16 and
ground.
- If 1 V or greater, repair the short to voltage on the circuit.
- If less than 1 V, replace the X50A Fuse Block - Underhood.
- Go to next step: If the M45 Rear Wiper Motor is not activated
16. Connect a 10 A fused jumper wire between the control circuit terminal 8
and B+.
17. Verify the M45 Rear Wiper Motor activates.
- If the M45 Rear Wiper Motor does not activate
- Ignition OFF, remove the jumper wire, disconnect the X2 harness
connector at the X50A Fuse Block -
Underhood.
- Test for infinite resistance between the control circuit terminal 16 and
ground.
- If less than infinite resistance, repair the short to ground on the
circuit.
- Go to next step: If less than 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, test or replace the X50A Fuse Block - Underhood.
- Go to next step: If the M45 Rear Wiper Motor activates
18. Test or replace the K9 Body Control Module.
Component Testing
Windshield Wiper/Washer Switch
1. Ignition OFF, disconnect the harness connector at the S82 Windshield
Wiper/Washer Switch.
2. Test for infinite resistance between the signal terminal 5 and the low
reference terminal 1 with the rear
window washer switch in the open position.
- If less than infinite resistance
Replace the S82 Windshield Wiper/Washer Switch.
- Go to next step: If infinite resistance
3. Verify the resistance reading is within the range specified below between
the signal circuit terminal 5 and the
low reference circuit terminal 1 by cycling the switch between Rear Wiper
position and Rear Washers
position.
- Rear Wiper : 624-644 Ω
- Rear Wiper Sweep : 1.99-2.01 kΩ
- Rear Washer : 6.11-6.13 kΩ
- If not within range specified
Replace the S82 Windshield Wiper/Washer Switch.
- Go to next step: If within range specified
4. All OK
Repair Instructions
Perform the Diagnostic Repair Verification after completing the repair.
- Rear Window Wiper Motor Replacement (5-Door Hatchback 68)Rear Window
Wiper Motor
Replacement (5-Door Wagon 35)
- Windshield Wiper and Washer Switch Replacement
- Control Module References or 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
SEE MORE:
NOTE: Examples used in this article are general in nature and do not
necessarily
relate to a specific engine or system. Illustrations and procedures have
been chosen to guide mechanic through engine overhaul process.
Descriptions of processes of cleaning, inspection, assembly and machine
shop prac
Diagnostic Instructions
Perform the Diagnostic System Check prior to using this diagnostic
procedure:Diagnostic System
Check - Vehicle
Review the description of Strategy Based Diagnosis:Strategy Based
Diagnosis
An overview of each diagnostic category can be found here:Diagnostic
Procedure