OBD Code B1345: Heated Backlite Input Circuit Short To Ground

Q: What does OBD code B1345 mean?

Heated Backlite Input Circuit Short To Ground. The heated rear window circuit is shorted to ground, meaning the electrical signal wire is touching a metal surface it shouldn't. It's like a power cord with damaged insulation touching a metal pipe.

Q: What are the symptoms of fault code B1345?

Rear defroster not functioning, B1345 fault code stored in ECU memory, Possible blown fuse or tripped circuit breaker for rear window heater

Q: How do I fix OBD fault code B1345?

Inspect and replace the rear defroster fuse if blown; check for correct amperage rating.. Visually inspect the heated backlite wiring for cuts, abrasion, or moisture damage and repair insulation as needed.. Replace the switch or control module if wiring is intact but short persists.

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What This Actually Means

In plain language — no jargon

The heated rear window circuit is shorted to ground, meaning the electrical signal wire is touching a metal surface it shouldn't. It's like a power cord with damaged insulation touching a metal pipe.

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Symptoms You May Notice

3 known symptoms for this code

Rear defroster not functioning

B1345 fault code stored in ECU memory

Possible blown fuse or tripped circuit breaker for rear window heater

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Embedded Systems Insight

What the ECU/ECM is actually computing

The ECU monitors the input signal voltage from the heated backlite switch circuit. When activated, it expects a normal operating voltage; if the circuit shorts to ground, voltage drops to 0V or near-ground potential. The ECU detects this abnormal low-voltage condition and triggers the fault code.

Voltage & Parameter Thresholds

Parameter	Normal Range	Fault Condition
Circuit Voltage (Active)	12V or signal present	0V or near-ground short
Circuit Resistance	>1000 ohms	<10 ohms (short to ground)

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Diagnostic & DIY Fix Guide

Check these in order — from cheapest to most complex

1

Fuse/Circuit Breaker

Inspect and replace the rear defroster fuse if blown; check for correct amperage rating.

2

Wiring harness and connectors

Visually inspect the heated backlite wiring for cuts, abrasion, or moisture damage and repair insulation as needed.

3

Heated backlite switch or module

Replace the switch or control module if wiring is intact but short persists.