Circuit Description
The body control module (BCM) controls and monitors the state of the WPR2 relay control circuit. When the windshield wiper switch is placed in to a high speed setting, a signal is applied to the BCM through the windshield wiper switch high signal circuit. The BCM then applies battery positive voltage to the WPR2 relay through the WPR2 relay control circuit. This energizes the WPR2 relay, allowing battery positive voltage to be applies from the FRT WPR fuse, through the switched contacts of the WPR1 relay and through the switched contracts of the WPR2 relay to the windshield wiper motor. Ground is applied at all times to the coil side of the WPR2 relay and to the windshield wiper motor from G200.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC B3875 WPR2 Relay Circuit
Conditions for Running the DTC
| • | The ignition is in the ON position. |
| • | The ignition voltage is between 9-16 volts. |
Conditions for Setting the DTC
The following conditions will cause the DTC to set:
| • | The BCM detects an short to battery positive voltage in the WPR2 relay control circuit for over 1 second. |
| • | The BCM detects an open or a short to ground in the WPR2 relay control circuit for over 1 second. |
Action Taken When the DTC Sets
The BCM will not activate the WPR2 relay.
Conditions for Clearing the DTC
| • | A current DTC B3875 will clear if the short to battery, a short to ground or an open in the WPR2 relay control circuit is no longer detected by the BCM. |
| • | A history DTC B3875 will clear after 100 consecutive ignition cycles if the condition for the malfunction is no longer present. |
| • | The BCM receives a clear code command from the scan tool. |
Diagnostic Aids
| • | If the DTC B3875 is a history DTC, the fault may be intermittent. Refer to Testing for Intermittent Conditions and Poor Connections . |
| • | The following conditions may cause an intermittent malfunction or occur: |
| - | An intermittent short to battery, a short to ground or an open in the WPR2 relay control circuit. |
| - | The WPR2 relay coil is intermittently shorted to battery. |
| - | The BCM is intermittently shorted to battery, shorted to ground or an open. |
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 | |
2 |
Do the high speed wipers operate? | Go to Testing for Intermittent Conditions and Poor Connections | Go to Step 3 |
3 |
Does the test lamp illuminate? | Go to Step 6 | Go to Step 4 |
4 |
Does the test lamp illuminate? | Go to Step 5 | Go to Step 7 |
5 | Using a test lamp, probe between the WPR2 relay control circuit and the WPR2 relay ground circuit. Does the test lamp illuminate? | Go to Step 9 | Go to Step 8 |
6 | Test for a short to battery positive voltage in the WPR2 relay control circuit. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 12 | Go to Step 10 |
7 | Test for a poor connection, an open, or a short to ground in the WPR2 relay control circuit. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 12 | Go to Step 10 |
8 | Test for a poor connection or an open in the ground circuit of the WPR2 relay. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 12 | Go to Step 11 |
9 | Replace the WPR2 relay. Refer to Relay Replacement . Did you complete the replacement? | Go to Step 11 | Go to Step 12 |
10 | Replace the body control module (BCM). Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 12 | -- |
11 | Replace the underhood electrical center. Refer to Underhood Electrical Center or Junction Block Replacement . Did you complete the replacement? | Go to Step 12 | -- |
12 |
Does the DTC reset? | Go to Step 2 | System OK |
