What Does B1287 Mean?
This code indicates that the Body Control Module (BCM) has detected a short to ground in the potentiometer circuit of the left air intake servo motor. The potentiometer provides position feedback for the servo motor that controls air distribution in the HVAC system. The BCM detected that the signal voltage from the potentiometer is being pulled to ground, preventing proper position sensing and control of the air intake door.
Common Causes
40%
Damaged or chafed wiring harness causing the potentiometer signal wire to contact ground
35%
Failed servo motor with internal potentiometer short to ground
15%
Corroded or moisture-damaged connector pins creating a ground path
10%
Failed or damaged Body Control Module with internal circuit fault
Diagnostic Steps
1
Step 1: Perform visual inspection of the left air intake servo motor, connector, and wiring harness for obvious damage, chafing, water intrusion, or corrosion. Pay special attention to areas where wiring passes through metal panels or near sharp edges.
2
Step 2: Disconnect the left air intake servo motor connector and measure resistance between the potentiometer signal wire (typically center pin) and ground with a digital multimeter. Should read open circuit (OL or >10k ohms); if continuity exists, trace the wiring harness for the short location.
3
Step 3: With connector still disconnected, measure resistance across the servo motor potentiometer terminals. Compare readings to manufacturer specifications (typically 1-10k ohms variable resistance). If shorted to ground internally or readings are abnormal, replace the servo motor.
4
Step 4: Reconnect servo motor and backprobe the signal wire at the BCM connector with a multimeter set to DC voltage. Key on, engine off, measure voltage while manually actuating the servo motor door (if accessible). Should see varying voltage between 0.5-4.5V; constant 0V indicates short to ground in harness.
5
Step 5: If wiring and servo motor test normal, suspect BCM internal fault. Check BCM ground connections and power supply circuits. Replace BCM only after confirming all external circuits are intact.
6
Step 6: After repair, clear codes, cycle HVAC through all modes and positions, verify smooth operation of air intake door, and road test to confirm code does not return.
Estimated Repair Cost
$150 - $650
Parts + labor, varies by vehicle and location
This code indicates that the Body Control Module (BCM) has detected a short to ground in the potentiometer circuit of the left air intake servo motor. The potentiometer provides position feedback for the servo motor that controls air distribution in the HVAC system. The BCM detected that the signal ...
The most common cause of B1287 (Servo Motor Potentiometer Airintake Left Circuit Short To Ground) is: Damaged or chafed wiring harness causing the potentiometer signal wire to contact ground
Typical repair costs for B1287 range from $150 to $650, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to continue driving as this affects only HVAC air distribution functionality. Climate control may not direct air properly to selected vents, but vehicle operation and safety systems are not impacted. Repair at convenience, though comfort may be reduced.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1287 to identify the root cause.
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Quick Info
Category
Body
System
HVAC Climate Control System
Difficulty
Type
Manufacturer
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