What Does B1549 Mean?
This diagnostic trouble code indicates that the Body Control Module (BCM) has detected an abnormal voltage condition in the power window master switch circuit, specifically a short to battery voltage. The BCM monitors the master window switch control circuits and has identified that one or more circuits are receiving constant battery voltage when they should be at a lower voltage or ground. This condition typically affects the driver's side master window control panel which operates all windows in the vehicle.
Common Causes
40%
Damaged or pinched wiring harness between the master window switch and BCM, causing chafing and exposure of copper wire to battery voltage
35%
Faulty power window master switch with internal short circuit creating unintended battery voltage path
15%
Water intrusion or liquid damage to master window switch causing corrosion and short circuit to power supply
10%
Failed or shorted Body Control Module internal window control driver circuit
Diagnostic Steps
1
Step 1: Perform visual inspection of the master window switch assembly and connector for signs of water damage, corrosion, burnt pins, or physical damage. Remove switch from door panel and inspect for liquid intrusion or debris.
2
Step 2: Disconnect the master window switch connector and use a digital multimeter to check for battery voltage (12-14V) on any of the control circuit pins at the BCM side of the harness with ignition on. All control circuits should read 0V or near ground with switch disconnected.
3
Step 3: Inspect the wire harness routing from driver's door through the door jamb boot to the body, looking for pinched, crushed, or chafed wires. Flex the harness while monitoring voltage on suspect circuits to identify intermittent shorts.
4
Step 4: If wiring tests normal, test the master switch itself by measuring resistance between the battery feed pin and each control circuit pin with the switch in rest position. Readings should be open circuit (infinite resistance), not low resistance indicating internal short.
5
Step 5: If all external components test normal, suspect BCM internal fault. Verify BCM ground circuits are intact and measure voltage at BCM connector pins corresponding to window control outputs with switch disconnected to confirm BCM is source of fault.
6
Step 6: After repair, clear codes, operate all windows through complete cycles, and monitor for code return. Verify proper window operation from all switch positions and confirm BCM shows no active faults.
Estimated Repair Cost
$150 - $800
Parts + labor, varies by vehicle and location
This diagnostic trouble code indicates that the Body Control Module (BCM) has detected an abnormal voltage condition in the power window master switch circuit, specifically a short to battery voltage. The BCM monitors the master window switch control circuits and has identified that one or more circ...
The most common cause of B1549 (Power Window Master Circuit Short To Battery) is: Damaged or pinched wiring harness between the master window switch and BCM, causing chafing and exposure of copper wire to battery voltage
Typical repair costs for B1549 range from $150 to $800, depending on the vehicle, location, and whether you do it yourself or go to a shop.
This code does not affect vehicle safety or driveability and the vehicle can be operated normally. The power windows may be inoperative or function erratically, which could be inconvenient but poses no immediate safety risk unless windows cannot be closed in inclement weather.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1549 to identify the root cause.
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Quick Info
Category
Body
System
Body Control / Power Window System
Difficulty
Type
Manufacturer
Recommended Tools
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