What Does B1236 Mean?
B1236 indicates the Body Control Module (BCM) has detected a loss of feedback signal from a power window motor or position sensor. The BCM monitors window position through feedback circuits to detect obstructions and control auto-up/down functions. When this signal is lost, the BCM cannot determine window position or verify motor operation, triggering this fault code.
Common Causes
35%
Faulty window motor with worn brushes or failed internal position sensor/hall effect sensor
30%
Damaged or corroded wiring harness between BCM and window motor, including broken wires or poor connections at connectors
20%
Failed window regulator with broken feedback mechanism or damaged position encoder
15%
BCM internal circuit failure or corrupted software requiring reprogramming
Diagnostic Steps
1
Step 1: Perform visual inspection of affected door's window motor connector and wiring harness for corrosion, water intrusion, or physical damage. Check connector pins for proper seating and signs of burning or corrosion
2
Step 2: Using a digital multimeter, backprobe the window motor feedback signal wire at the motor connector while operating the window switch. Verify voltage changes smoothly (typically 0.5-4.5V range) as window moves, indicating feedback signal generation
3
Step 3: Remove door panel and inspect window motor and regulator assembly for mechanical binding, damaged gears, or broken position sensor components. Manually move window to check for smooth operation without obstruction
4
Step 4: Test window motor independently by applying direct 12V power to motor terminals. If motor runs but feedback signal remains absent on signal wire, replace window motor assembly
5
Step 5: If wiring and motor test good, use bidirectional controls in scan tool to command window operation while monitoring BCM data stream for feedback signal reception. Compare to opposite door's values if available
6
Step 6: After repair, clear codes, perform window auto-up/down initialization procedure per manufacturer specifications, cycle window through full range 10 times, and verify code does not return
Estimated Repair Cost
$150 - $650
Parts + labor, varies by vehicle and location
B1236 indicates the Body Control Module (BCM) has detected a loss of feedback signal from a power window motor or position sensor. The BCM monitors window position through feedback circuits to detect obstructions and control auto-up/down functions. When this signal is lost, the BCM cannot determine ...
The most common cause of B1236 (Window Feedback Loss of Signal) is: Faulty window motor with worn brushes or failed internal position sensor/hall effect sensor
Typical repair costs for B1236 range from $150 to $650, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to drive. Window may not operate in auto mode or may lack anti-pinch protection. Manual window operation may be limited or non-functional on affected window. Repair at convenience but address before inclement weather.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1236 to identify the root cause.
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Quick Info
Category
Body
System
Body Control/Power Window System
Difficulty
Type
Manufacturer
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