What Does B1344 Mean?
This code indicates the Body Control Module (BCM) has detected an open circuit in the heated rear window (backlite) defogger input circuit. The BCM monitors the control circuit for the rear window defogger relay or switch and has detected a break in continuity, preventing proper operation of the heated rear window system. This is a body system fault that affects passenger comfort but not vehicle operation or safety systems.
Common Causes
35%
Broken or corroded wiring between BCM and rear window defogger relay/switch, including damaged connectors or terminals
30%
Failed rear window defogger relay or control switch with internal open circuit
20%
Faulty Body Control Module (BCM) with failed input driver or internal circuit fault
10%
Blown fuse or fusible link in the defogger control circuit
5%
Loose or corroded ground connection in the defogger control circuit
Diagnostic Steps
1
Step 1: Visually inspect all fuses related to the rear window defogger system in both underhood and interior fuse boxes. Check for blown fuses, corrosion, or loose fuse connections. Replace any blown fuses and retest.
2
Step 2: Locate the rear window defogger relay (typically in underhood fuse/relay box). Remove relay and test relay coil resistance with multimeter (should be 60-120 ohms typically). Test relay operation by applying 12V to coil terminals and verifying contacts close with audible click and continuity.
3
Step 3: With relay removed, check for battery voltage at the relay socket power supply terminal (key on) using multimeter. Verify ground circuit has less than 0.5 ohms resistance to battery negative. Check BCM trigger circuit for continuity to BCM connector.
4
Step 4: Inspect BCM connector for corrosion, bent pins, or moisture intrusion. Backprobe the BCM defogger input circuit wire (consult wiring diagram for specific terminal) and check for proper voltage signal when defogger switch is activated. Expected reading should be 0V or 12V depending on switch position.
5
Step 5: Trace wiring harness from BCM to defogger relay/switch checking for breaks, chafing, or damage. Pay special attention to areas where harness passes through bulkheads, door jambs, or near sharp edges. Check all inline connectors for corrosion and proper pin tension.
6
Step 6: If all wiring, relay, and connections test good, suspect BCM internal fault. Verify BCM software is up to date and perform BCM reset/relearn procedure per manufacturer specifications before replacing BCM.
Estimated Repair Cost
$75 - $650
Parts + labor, varies by vehicle and location
This code indicates the Body Control Module (BCM) has detected an open circuit in the heated rear window (backlite) defogger input circuit. The BCM monitors the control circuit for the rear window defogger relay or switch and has detected a break in continuity, preventing proper operation of the hea...
The most common cause of B1344 (Heated Backlite Input Circuit Open) is: Broken or corroded wiring between BCM and rear window defogger relay/switch, including damaged connectors or terminals
Typical repair costs for B1344 range from $75 to $650, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle is completely safe to drive with this fault. The only impact is loss of heated rear window defogger function, which may affect rear visibility in cold or humid weather conditions. Repair can be scheduled at convenience unless driving in conditions requiring rear window defogging.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1344 to identify the root cause.
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Quick Info
Category
Body
System
Body Electrical System
Difficulty
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Manufacturer
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