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Home >> Buick >> 2007 >> Lucerne CX >> Repair and Diagnosis >> External Pages >> Different car >> Section 117 (Wiper System & Washer System) >> Diagnostic Information and Procedures >> DTC B3874 - Wiper Low Speed Relay Circuit >> Diagnostic Aids

Diagnostic Aids

WARNING: This page is about a different car, the 2006 Buick LaCrosse and 2006 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.

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

DTC B3874

Step Action Yes No
Schematic Reference: Wiper/Washer System Schematics 
Connector End View Reference: Master Electrical Component List in Wiring Systems
1 Did you perform the Diagnostic System Check - Vehicle? Go to Step 2  Go to Diagnostic System Check - Vehicle in Vehicle DTC Information
2
  1. Turn the ignition to the ON position.
  2. On the wiper switch, select a low speed.
Do the windshield wipers operate?		 Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems Go to Step 3 
3
  1. Turn the ignition to the OFF position.
  2. Turn the wiper switch OFF.
  3. Remove the WIPER relay from the underhood fuse block.
  4. Using a test lamp connected to ground, probe the WIPER relay control circuit at the underhood fuse block.
Does the test lamp illuminate?		 Go to Step 8  Go to Step 4 
4
  1. Leave the test lamp connected.
  2. Turn the ignition to the ON position.
  3. Turn the wiper switch to a low position.
Does the test lamp illuminate?		 Go to Step 5  Go to Step 6 
5
  1. Turn the wiper switch to the OFF position.
  2. Turn the ignition to the OFF position.
  3. Using a test lamp, probe the WIPER relay control circuit and the ground circuit of the WIPER relay at the underhood fuse block.
  4. Turn the ignition to the ON position.
  5. Turn the wiper switch to a low position.
Does the test lamp illuminate?		 Go to Step 9  Go to Step 7 
6 Test for a poor connection, an open or short to ground in the WIPER relay control circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 Go to Step 12  Go to Step 10 
7 Test for a poor connection or an open in the ground circuit of the WIPER relay. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 Go to Step 12  Go to Step 11 
8 Repair a short to battery positive voltage in the WIPER relay control circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you complete the repair?		 Go to Step 12  -
9
  1. Replace the WIPER relay. Refer to Relay Replacement (Within an Electrical Center) or Relay Replacement (Attached to Wire Harness) in Wiring Systems.
  2. Operate the vehicle within the Conditions for Running the DTC.
Does the DTC reset?		 Go to Step 11  Go to Step 12 
10 Replace the body control module (BCM). Refer to Control Module References in Computer/Integrating Systems 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 in Wiring Systems.
Did you complete the replacement?		 Go to Step 12  -
12
  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
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