What Does B1839 Mean?
This code indicates that the Body Control Module (BCM) has detected an electrical fault in the rear wiper motor circuit. The BCM monitors voltage, current, and continuity in the rear wiper motor circuit and sets this code when it detects an open circuit, short to ground, short to power, or excessive current draw. This is a manufacturer-specific body control code that affects the rear window wiper system functionality.
Common Causes
35%
Failed rear wiper motor with internal short or open winding
30%
Damaged wiring harness or corroded connector between BCM and rear wiper motor
20%
Blown fuse or faulty relay in rear wiper motor circuit
10%
Failed BCM output driver circuit for rear wiper control
5%
Binding or seized rear wiper linkage causing motor overcurrent
Diagnostic Steps
1
Step 1: Perform visual inspection of rear wiper motor, wiring harness, and connectors for obvious damage, corrosion, water intrusion, or disconnected plugs. Check rear wiper fuse for continuity and verify proper fuse amperage rating.
2
Step 2: Disconnect rear wiper motor connector and use a digital multimeter to measure resistance across motor terminals. Expected reading should be 2-8 ohms typically; infinite resistance indicates open motor winding, near-zero resistance indicates shorted windings.
3
Step 3: With motor disconnected, turn ignition on and activate rear wiper switch while measuring voltage at motor connector harness side. Should see battery voltage (12-14V) when activated; no voltage indicates wiring/relay/BCM fault upstream of motor.
4
Step 4: Check for proper ground circuit by measuring voltage drop between motor ground terminal and battery negative with motor operating (reconnect motor temporarily). Voltage drop should be less than 0.2V; higher reading indicates poor ground connection.
5
Step 5: If wiring and ground circuits test good, perform current draw test on rear wiper motor. Connect ammeter in series with motor power supply and operate wiper. Normal draw is typically 2-5 amps; excessive current (8+ amps) indicates binding linkage or failing motor.
6
Step 6: After repairs, clear codes, cycle rear wiper through all modes multiple times, and verify code does not return. Monitor BCM data stream for proper motor circuit feedback signals during operation.
Estimated Repair Cost
$120 - $450
Parts + labor, varies by vehicle and location
This code indicates that the Body Control Module (BCM) has detected an electrical fault in the rear wiper motor circuit. The BCM monitors voltage, current, and continuity in the rear wiper motor circuit and sets this code when it detects an open circuit, short to ground, short to power, or excessive...
The most common cause of B1839 (Wiper Rear Motor Circuit Failure) is: Failed rear wiper motor with internal short or open winding
Typical repair costs for B1839 range from $120 to $450, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to continue driving as this only affects rear window visibility cleaning. Repair when convenient, though reduced rear visibility in rain or snow may increase accident risk in poor weather conditions.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1839 to identify the root cause.
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Quick Info
Category
Body
System
Body Control/Rear Wiper System
Difficulty
Type
Manufacturer
Recommended Tools
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