Rear Washer Relay Circuit
Table of contents
B3811 CADILLAC Possible Causes
- Faulty Rear Window Washer Pump
- Rear Window Washer Pump harness is open or shorted
- Rear Window Washer Pump circuit poor electrical connection
- Faulty Body Control Module (BCM)
How do I fix code B3811 CADILLAC?
Check the “Possible Causes” listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector’s pins.
Cost of diagnosing the B3811 CADILLAC code
The cost of diagnosing the B3811 CADILLAC code is 1.0 hour of labor. The auto repair labor rates vary by location, your vehicle’s make and model, and even your engine type. Most auto repairs shops charge between $75 and $150 per hour.
Possible Symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
B3811 CADILLAC Description
The Body Control Module (BCM) controls the rear washer based on an input from the rear wiper switch, which is part of the turn signal/multifunction switch. The BCM monitors the rear wiper switch through separate signal circuits and a ground circuit. The rear wiper switch uses a resistor ladder to determine low speed, intermittent, and rear washer operation. The BCM monitors applies and monitors voltage on the rear wiper switch signal circuit. 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 will respond by commanding the specific rear wiper function.
The rear window washer pump is controlled by the BCM controls through the rear washer pump relay. When the rear wash switch is pressed, ignition voltage from the BCM is applied to the rear washer relay control circuit. The rear washer relay control circuit is used to energize the relay coil and close the rear washer pump control circuit to B+.