What Does B1842 Mean?
This diagnostic trouble code indicates the Body Control Module (BCM) has detected an abnormal voltage condition in the front windshield wiper power supply circuit. Specifically, the circuit is showing voltage when it should be off, suggesting an unintended connection to battery voltage. This typically means current is flowing through the wiper motor circuit even when the wiper switch is in the off position.
Common Causes
40%
Damaged or chafed wiring harness causing direct short to battery voltage in wiper power feed circuit
30%
Faulty wiper motor with internal short circuit creating path to battery voltage
20%
Failed multifunction switch or wiper control stalk with internal short to power
10%
Defective Body Control Module with failed internal wiper relay or driver circuit
Diagnostic Steps
1
Step 1: Perform visual inspection of the wiper motor wiring harness from the BCM connector to the wiper motor, checking for chafed, melted, or damaged insulation, paying special attention to areas where harness passes through firewall or contacts metal edges
2
Step 2: Disconnect the wiper motor connector and use a digital multimeter to measure voltage at the wiper motor power feed wire with ignition on and wiper switch off; reading should be 0V (battery voltage indicates wiring harness short upstream of motor)
3
Step 3: With wiper motor disconnected, measure resistance between the wiper motor power feed circuit and battery positive at the BCM harness connector; reading should be infinite ohms (low resistance confirms short to battery in harness)
4
Step 4: If harness tests good, reconnect wiper motor and backprobe the connector to measure current draw with wipers off using amp clamp meter; any current flow indicates failed wiper motor with internal short
5
Step 5: If motor tests good, remove and inspect multifunction switch connector for corrosion or terminal damage, then test switch resistance between power feed and output terminals in off position; should read infinite ohms
6
Step 6: After repair, clear codes and operate wipers through all switch positions to verify proper operation and confirm no voltage present at motor connector when switch is off
Estimated Repair Cost
$120 - $650
Parts + labor, varies by vehicle and location
This diagnostic trouble code indicates the Body Control Module (BCM) has detected an abnormal voltage condition in the front windshield wiper power supply circuit. Specifically, the circuit is showing voltage when it should be off, suggesting an unintended connection to battery voltage. This typical...
The most common cause of B1842 (Wiper Front Power Circuit Short To Battery) is: Damaged or chafed wiring harness causing direct short to battery voltage in wiper power feed circuit
Typical repair costs for B1842 range from $120 to $650, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle is safe to drive, but wipers may operate unexpectedly or not function when needed, which could significantly impair visibility during inclement weather. Repair should be completed promptly before rainy conditions to maintain safe operation.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1842 to identify the root cause.
OBDHut Mobile App
Scan codes directly from your car with the OBDHut app.
Coming Soon
Quick Info
Category
Body
System
Body Control System - Wiper/Washer
Difficulty
Type
Manufacturer
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
