What Does B1343 Mean?
This diagnostic trouble code indicates the Body Control Module (BCM) has detected an electrical fault in the heated rear window (backlite) control circuit. The BCM monitors the input signal from the heated backlite switch or relay and has detected an abnormal voltage, open circuit, or short circuit condition. This prevents the heated rear window system from functioning properly, which is used to defog or de-ice the rear glass.
Common Causes
35%
Faulty heated backlite relay or control module
30%
Damaged wiring harness or corroded connector between BCM and heated backlite switch/relay
20%
Defective heated backlite switch or button
10%
Blown fuse or fusible link in heated backlite circuit
5%
Failed Body Control Module (BCM)
Diagnostic Steps
1
Step 1: Inspect the heated backlite fuse in the fuse panel and verify continuity using a test light or multimeter; replace if blown and identify cause of overload
2
Step 2: Locate the heated backlite switch and inspect the connector for corrosion, bent pins, or loose connections; clean or repair as needed
3
Step 3: Using a digital multimeter, test for proper voltage at the heated backlite relay or control module input terminal with the switch activated; should see battery voltage (12-14V)
4
Step 4: Check wiring harness continuity between the BCM connector and heated backlite switch using a multimeter in ohms mode; should read less than 5 ohms for good connection
5
Step 5: Test the heated backlite relay by swapping with an identical relay from another system or bench-test with power and ground; relay should click and show continuity when energized
6
Step 6: Clear codes, operate the heated backlite system, and verify repair by monitoring live data for proper switch input signal at BCM
Estimated Repair Cost
$75 - $350
Parts + labor, varies by vehicle and location
This diagnostic trouble code indicates the Body Control Module (BCM) has detected an electrical fault in the heated rear window (backlite) control circuit. The BCM monitors the input signal from the heated backlite switch or relay and has detected an abnormal voltage, open circuit, or short circuit ...
The most common cause of B1343 (Heated Backlite Input Circuit Failure) is: Faulty heated backlite relay or control module
Typical repair costs for B1343 range from $75 to $350, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to continue driving as this only affects rear window defrosting capability. However, reduced rear visibility in cold or humid weather due to fog or ice accumulation on the rear window may present a safety concern and should be repaired promptly.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1343 to identify the root cause.
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Quick Info
Category
Body
System
Body Electrical System
Difficulty
Type
Manufacturer
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