What Does B1345 Mean?
This code indicates that the Body Control Module (BCM) has detected a short to ground condition in the heated rear window (backlite) input circuit. The control module expected to see a specific voltage or resistance on the circuit that activates the rear window defroster, but instead detected an abnormally low voltage consistent with the circuit being grounded. This prevents proper operation of the heated rear window system.
Common Causes
45%
Damaged or chafed wiring harness causing short to ground between BCM and rear window defroster grid
25%
Faulty heated backlite relay with internal short to ground
20%
Corroded or moisture-damaged connector at rear window defroster creating ground path
10%
Failed rear window defroster grid or switch with internal short circuit
Diagnostic Steps
1
Step 1: Perform visual inspection of rear window defroster wiring harness from BCM to rear window, paying special attention to areas where harness passes through body panels, trunk hinges, and lift gate areas for chafing, pinching, or damaged insulation
2
Step 2: Using a digital multimeter, disconnect the heated backlite relay and measure resistance from the BCM input circuit terminal to ground with defroster switch off - should read open circuit (OL) or very high resistance; reading below 10 ohms confirms short to ground
3
Step 3: If relay tests good, disconnect the rear window defroster grid connector and retest circuit resistance to ground - if short disappears, problem is in grid or connections; if short remains, problem is in wiring harness between BCM and grid
4
Step 4: Inspect all connectors in the circuit for moisture intrusion, corrosion, or bent pins causing ground contact - clean and apply dielectric grease as needed
5
Step 5: If wiring harness is damaged, repair or replace affected section, ensuring proper routing away from sharp edges and securing with appropriate clips
6
Step 6: Clear codes, operate heated backlite system through multiple cycles, and verify code does not return and system functions properly
Estimated Repair Cost
$100 - $450
Parts + labor, varies by vehicle and location
This code indicates that the Body Control Module (BCM) has detected a short to ground condition in the heated rear window (backlite) input circuit. The control module expected to see a specific voltage or resistance on the circuit that activates the rear window defroster, but instead detected an abn...
The most common cause of B1345 (Heated Backlite Input Circuit Short To Ground) is: Damaged or chafed wiring harness causing short to ground between BCM and rear window defroster grid
Typical repair costs for B1345 range from $100 to $450, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to continue driving as this affects only rear window defroster operation. Reduced rear visibility in cold or wet weather conditions may occur until repaired, but does not present immediate safety concern in normal conditions.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1345 to identify the root cause.
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Quick Info
Category
Body
System
Body Electrical System
Difficulty
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