B3874
DTC B3874
Circuit Description
The body control module (BCM) controls and monitors the state of the wiper control circuit. When the windshield wiper switch is placed in to a low speed setting, a signal is applied to the BCM. The BCM then applies battery positive voltage to the coil side of the WPR1 relay through the WPR1 relay control circuit. This energizes the WPR1 relay, allowing battery positive voltage from the FRT WPR fuse through the switched side of the WPR1 relay to the windshield wiper motor. Ground is applied at all times to the coil side of the WPR1 relay and the windshield wiper motor form G200.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC B3874 Wiper Low Speed 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 WPR1 relay control circuit for over 1 second.
* The BCM detects a short to ground or an open in the WPR1 relay control circuit.
Action Taken When the DTC Sets
The BCM will not activate the output.
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. Component Tests and General Diagnostics
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