B1346
Heated Backlite Input Circuit Short To Battery
Body Chassis/Safety Rear Defroster Circuit 🟢 Low — Fix at next service
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What This Actually Means
In plain language — no jargon

The heated rear window circuit is detecting full battery voltage when it shouldn't be, like a switch that's stuck in the 'on' position. This means there's likely a wiring short or component failure preventing normal current flow control.

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Symptoms You May Notice
3 known symptoms for this code
Rear window defroster stays on continuously or won't turn off
Rear window defroster doesn't work at all
Warning light or fault code displayed on dashboard
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Embedded Systems Insight
What the ECU/ECM is actually computing

The ECU monitors the heated backlite circuit voltage and current draw. It expects controlled voltage levels when the defroster is commanded on or off. A short to battery causes the ECU to detect continuous maximum voltage instead of normal modulated signals.

Voltage & Parameter Thresholds

Parameter Normal Range Fault Condition
Circuit Voltage 0V (off) to 12-14V (on, controlled) Continuous 12-14V regardless of command
Current Draw 0A (off) to controlled amperage (on) Sustained high current unrelated to input signal
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Diagnostic & DIY Fix Guide
Check these in order — from cheapest to most complex
1
Wiring harness connectors
Inspect and reseat all connectors at the rear defroster switch and module for corrosion or loose terminals.
2
Heated backlite switch
Replace the faulty defroster switch if it's stuck closed or showing continuity when off.
3
Wiring harness
Repair or replace damaged wiring between the switch, relay, and rear window heating element if visible chafing or shorts are found.