What Does B1550 Mean?
This code indicates the Body Control Module (BCM) has detected a short to ground condition in the power window master switch circuit. The master switch, typically located in the driver's door, controls all vehicle windows and sends signals to the BCM. When the circuit voltage drops below expected parameters due to a direct ground connection, the BCM sets this fault code and may disable window operation to prevent component damage.
Common Causes
45%
Damaged or chafed wiring in the driver's door harness causing short to ground
30%
Failed power window master switch with internal short circuit
15%
Water intrusion or corrosion in master switch connector causing ground path
10%
Faulty Body Control Module with internal circuit failure
Diagnostic Steps
1
Step 1: Perform visual inspection of the driver's door wiring harness, particularly in the door jamb area where flexing occurs. Look for pinched, chafed, or damaged wires, worn insulation, or signs of previous repairs. Check for water intrusion in the door panel.
2
Step 2: Disconnect the power window master switch connector and inspect terminals for corrosion, water damage, or bent pins. Using a digital multimeter set to ohms, test for continuity between each switch circuit terminal and ground with switch disconnected. Any continuity indicates a short to ground in the wiring harness.
3
Step 3: If harness tests good, perform resistance testing on the master switch itself. With switch disconnected, measure resistance between the BCM control circuit terminals and the switch ground terminal in various switch positions. Compare readings to manufacturer specifications; near-zero resistance indicates internal switch failure.
4
Step 4: If switch and visible wiring are intact, test the circuit at the BCM connector. Disconnect BCM and measure resistance from the master switch control circuit pins to chassis ground. Reading should be infinite (open circuit). Low resistance confirms wiring fault between BCM and switch.
5
Step 5: After locating and repairing the short circuit (wire repair, switch replacement, or connector cleaning), reconnect all components, clear codes, and verify proper window operation in all positions. Cycle each window multiple times and verify code does not return.
Estimated Repair Cost
$100 - $600
Parts + labor, varies by vehicle and location
This code indicates the Body Control Module (BCM) has detected a short to ground condition in the power window master switch circuit. The master switch, typically located in the driver's door, controls all vehicle windows and sends signals to the BCM. When the circuit voltage drops below expected pa...
The most common cause of B1550 (Power Window Master Circuit Short To Ground) is: Damaged or chafed wiring in the driver's door harness causing short to ground
Typical repair costs for B1550 range from $100 to $600, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to continue driving as this is a convenience feature failure. Windows may be inoperative or function intermittently, which could affect ventilation and emergency exit capability. Repair at earliest convenience, prioritize if driver's window is completely inoperable.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1550 to identify the root cause.
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Quick Info
Category
Body
System
Body Control and Convenience Systems
Difficulty
Type
Manufacturer
Recommended Tools
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