What Does B1819 Mean?
This code indicates the Body Control Module (BCM) has detected an open circuit in the relay coil that controls the rear wiper motor's upward or park position. The BCM attempted to energize the relay coil to operate the rear wiper but detected no current flow or infinite resistance, suggesting a broken wire, failed relay, or poor connection in the control circuit. This is a manufacturer-specific code, so exact implementation varies by vehicle make.
Common Causes
40%
Open circuit in wiring between BCM and rear wiper relay coil due to broken wire, chafed insulation, or corroded connector pins
35%
Failed rear wiper motor relay with open coil winding or internal relay failure
15%
Corroded or loose ground connection for the relay coil circuit
10%
Failed BCM with internal driver circuit failure preventing relay coil energization
Diagnostic Steps
1
Step 1: Locate the rear wiper relay (typically in underhood fuse/relay box or rear cargo area). Visually inspect relay and connector for corrosion, heat damage, or loose fit. Remove relay and check socket terminals for damage or pushed-back pins.
2
Step 2: Using a digital multimeter, measure resistance across the relay coil terminals (typically pins 85 and 86). Normal reading should be 50-120 ohms. Infinite resistance confirms failed relay coil.
3
Step 3: With relay removed and ignition on, use multimeter to check for battery voltage on the relay socket power supply pin and continuity to ground on the ground pin. Then backprobe the BCM control wire pin and activate rear wiper function to verify BCM is providing ground or voltage signal (depending on relay type).
4
Step 4: If no control signal present from BCM, trace wiring harness from relay socket back to BCM connector, checking for opens, shorts, or damaged wiring. Pay special attention to areas where harness flexes or passes through grommets near liftgate hinge.
5
Step 5: Check BCM connector terminals for corrosion, bent pins, or water intrusion. If wiring and connections are intact but BCM provides no output signal, BCM internal driver circuit may be failed and requires module replacement or reprogramming.
6
Step 6: After repairs, clear codes, cycle rear wiper through all modes multiple times, and verify code does not return. Test in various weather conditions if possible to ensure reliable operation.
Estimated Repair Cost
$75 - $450
Parts + labor, varies by vehicle and location
This code indicates the Body Control Module (BCM) has detected an open circuit in the relay coil that controls the rear wiper motor's upward or park position. The BCM attempted to energize the relay coil to operate the rear wiper but detected no current flow or infinite resistance, suggesting a brok...
The most common cause of B1819 (Wiper Rear Motor Up Relay Coil Circuit Open) is: Open circuit in wiring between BCM and rear wiper relay coil due to broken wire, chafed insulation, or corroded connector pins
Typical repair costs for B1819 range from $75 to $450, depending on the vehicle, location, and whether you do it yourself or go to a shop.
This is not a safety-critical issue and the vehicle is safe to drive. Rear visibility may be compromised during inclement weather if rear wiper is inoperative, which could pose a minor safety concern in rain or snow.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1819 to identify the root cause.
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Quick Info
Category
Body
System
Body Control System - Rear Wiper
Difficulty
Type
Manufacturer
Recommended Tools
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