Rear Wiper Switch Signal B Short to Ground
The Body Control Module (BCM) has detected a short to ground on the 'B' signal circuit of the rear wiper selector switch. This circuit typically corresponds to a specific switch position such as 'Intermittent' or 'Low'. The fault prevents the BCM from correctly interpreting the driver's request, disabling the affected wiper function.
1. Commonly Affected Makes
2. Most Common Causes
- Faulty rear wiper switch (on steering column or console) with internal short
- Chafed or pinched wiring in the signal 'B' circuit contacting chassis/body ground
- Corrosion, moisture, or bent terminals at the switch or BCM connector
- Internal BCM failure in the pull-up driver for that circuit
3. Symptoms You Will Notice
- Rear wiper does not operate in one or more positions
- Rear wiper may run continuously or not at all
4. Step-by-Step Diagnosis
Check for technical service bulletins (TSBs) related to the rear wiper system
Inspect the rear wiper switch and its connector for damage, corrosion, or bent pins
Test the signal 'B' circuit for continuity to ground using a multimeter
If wiring is intact, substitute a known-good switch to isolate the fault
If switch replacement does not resolve, test BCM output and consider BCM replacement
5. Frequently Asked Questions
Is it safe to drive?▼
Yes, the vehicle remains safe to drive. The rear wiper function may be partially or fully inoperative, but it does not affect braking, steering, or other critical systems.
How much does it cost to fix?▼
Repair costs typically range from $100 to $400, depending on whether the issue is a simple wiring repair, switch replacement, or BCM replacement.