GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2005 🢒 Terraza - 4WD 🢒 Brakes 🢒 Park Brake 🢒 DTC B3922

Circuit Description

The body control module (BCM) monitors the windshield wiper switch low signal circuit. When the wiper switch is placed in a low position, a signal is applied to the BCM through the windshield wiper switch low signal circuit. The BCM then applies a battery positive voltage to the WPR1 relay control circuit which energizes the WPR1 relay, allowing the battery positive voltage from FTR WPR fuse through the switched side of the WPR1 relay to the windshield wiper motor.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B3922 Front Wiper Select Circuit

Conditions for Running the DTC
    • The ignition switch is in the ON position.
    • The ignition voltage is between 9-16 volts.

Conditions for Setting the DTC

The BCM detects an short to battery positive voltage on the windshield wiper switch low signal circuit.

Action Taken When the DTC Sets

The windshield wipers will only function in the high mode.

Conditions for Clearing the DTC
    • The DTC will clear on current status after the condition for setting the fault is corrected.
    • A history DTC will clear after 100 consecutive ignition cycles without a fault present.
    • History and current DTCs can be cleared using a scan tool.

Diagnostic Aids

Perform a visual inspection for loose or poor connections at all related components. Refer to Testing for Intermittent Conditions and Poor Connections .

Step

Action

Yes

No

Schematic Reference: Wiper/Washer Schematics

Connector End View Reference: Master Electrical Component List

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2
  1. Install a scan tool.
  2. Turn the ignition to the ON position.
  3. Using a scan tool observe the Wiper Washer Switch parameter in the input list.
  4. Rotate the wiper washer switch through all the positions.

Does the scan tool display the correct positions?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3
  1. Turn the ignition to the OFF position.
  2. Disconnect the body control module (BCM) connector C3.
  3. At the BCM connector C3, install a jumper between ground and ground supply circuit to the windshield wiper/washer switch.
  4. Turn the wiper washer switch to the off position.
  5. Using a test lamp connected to ground, probe the wiper switch low signal circuit at the BCM connector C3.

Does the test lamp illuminate?

Go to Step 7

Go to Step 4

4
  1. Remove the ground jumper.
  2. Using a test lamp connected to battery positive voltage, probe the wiper switch low signal circuit at the BCM connector C3.

Does the test lamp illuminate?

Go to Step 8

Go to Step 5

5
  1. Install a jumper between ground and the ground supply circuit to the wiper/washer switch.
  2. Using a test lamp connected to battery positive voltage, probe the wiper switch low signal circuit at the BCM connector C3.
  3. Turn the wiper switch to all of the low settings.

Does the test lamp illuminate at each switch position?

Go to Step 9

Go to Step 6

6

Test for a poor connection or an open in the wiper switch low signal circuit. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 11

Go to Step 10

7

Repair a short to battery positive voltage in the wiper switch low signal circuit. Refer to Circuit Testing and Wiring Repairs .

Did you complete the repair?

Go to Step 11

--

8

Repair a short to ground in the wiper switch low signal circuit. Refer to Circuit Testing and Wiring Repairs .

Did you complete the repair?

Go to Step 11

--

9

Replace the BCM. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 11

--

10

Replace the windshield wiper/washer switch. Refer to Turn Signal Multifunction Switch Replacement .

Did you complete the replacement?

Go to Step 11

--

11
  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

Go to Step 2

System OK