What Does B2187 Mean?
This diagnostic trouble code indicates that the Body Control Module (BCM) has detected an abnormal electrical condition in the rear wiper select switch circuit labeled 'B'. Specifically, the circuit voltage has dropped below the expected threshold, suggesting the signal wire is making unintended contact with vehicle ground. This prevents the BCM from properly interpreting the switch position and controlling rear wiper operation.
Common Causes
45%
Damaged or chafed wiring harness between rear wiper switch and BCM causing short to ground
30%
Failed rear wiper switch with internal short circuit to ground
15%
Corroded or moisture-damaged connector pins at switch or BCM causing ground path
10%
Body Control Module internal fault on switch input circuit
Diagnostic Steps
1
Step 1: Perform visual inspection of rear wiper switch assembly, connectors, and accessible wiring for obvious damage, corrosion, water intrusion, or chafing against sharp edges or moving components
2
Step 2: Disconnect the rear wiper switch connector and measure resistance between the switch signal circuit B terminal and vehicle ground using a digital multimeter - should read infinite resistance (open circuit) if wiring is intact
3
Step 3: If Step 2 shows low resistance, inspect and trace the wiring harness from switch to BCM for pinch points, damage, or ground contact. If infinite resistance is found, test the switch itself by measuring resistance across terminals while cycling through positions per manufacturer specifications
4
Step 4: Reconnect components if wiring and switch test good, then monitor live data on scan tool while operating rear wiper switch through all positions to verify BCM receives proper voltage signals (typically 0V, 2.5V, 5V reference depending on position)
5
Step 5: If all previous tests pass but code persists, suspect BCM internal fault - verify proper ground and power supply to BCM, then consider BCM replacement or professional reprogramming/repair
6
Step 6: After repair, clear codes, cycle rear wiper through all functions multiple times, and road test to confirm proper operation and verify code does not return
Estimated Repair Cost
$75 - $450
Parts + labor, varies by vehicle and location
This diagnostic trouble code indicates that the Body Control Module (BCM) has detected an abnormal electrical condition in the rear wiper select switch circuit labeled 'B'. Specifically, the circuit voltage has dropped below the expected threshold, suggesting the signal wire is making unintended con...
The most common cause of B2187 (Rear Wiper Select Switch "B" Short to Ground) is: Damaged or chafed wiring harness between rear wiper switch and BCM causing short to ground
Typical repair costs for B2187 range from $75 to $450, depending on the vehicle, location, and whether you do it yourself or go to a shop.
This code does not affect vehicle safety or drivability and it is safe to continue operating the vehicle. Rear wiper functionality may be inoperative or erratic, which could reduce rear visibility in inclement weather, but this is not a critical safety concern requiring immediate repair.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B2187 to identify the root cause.
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Quick Info
Category
Body
System
Body Control System / Wiper/Washer System
Difficulty
Type
Generic (SAE)
Recommended Tools
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