B1346

Code

Other B — Body

Heated Backlite Input Circuit Short To Battery

Brand: Other

Type: B — Body

Views: UK: 29 EN: 29 RU: 21

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Damaged or frayed wiring harness contacting a constant 12V source
Shorted connector or terminal on the heated backlite switch, relay, or control module
Failed relay stuck closed or shorted internally to battery voltage
Corroded or bridged connector pins that supply battery voltage
Aftermarket accessory or recent repair introduced a short to battery

Scan tool: read B1346 and any related codes, note freeze frame/voltage data
Visual inspection of backlite wiring, connectors, and relay for damage or corrosion
Check fuses and fusible links for proper rating and signs of bypassing
Measure voltage at the heated backlite connector and control module pin with switch off/on
Continuity and resistance check of relay coil and switch circuits
Inspect for recent repairs or aftermarket additions near the rear wiring

Input/control line expected: ~0 V (inactive) and ~12 V (active) relative to vehicle ground
Fault condition: input reads constant battery voltage (~11–14.5 V) when it should be low
Defogger element resistance typically low-ohms (varies by vehicle); control signal is low-current for logic input
Relay coil continuity: typically several ohms to a few tens of ohms depending on design

Read and record all stored codes and freeze-frame data with a scan tool. Note battery voltage at time of fault.
Visually inspect rear window harness, connectors, switch, and relay for burn, corrosion, or damage.
With ignition ON, back-probe the heated backlite input/control pin at the BCM or relay connector. Verify voltage with defogger switch OFF — a fault will show ~battery voltage.
Disconnect the heated backlite connector at the rear element and re-check the input/control line voltage. If voltage drops to 0 V, the element or its harness is likely shorting to battery; if still at battery, fault is upstream (switch/relay/BCM).
Inspect and test the defogger relay: remove relay, test coil and contact continuity, and isolate relay socket wiring. Replace relay if contacts are welded.
If harness suspected, perform resistance/continuity checks to battery positive to locate short. Wiggle test along harness while monitoring voltage to find intermittent contact.
Repair damaged wiring, replace corroded connectors, or replace faulty relay/switch/module as indicated. Use proper gauge wire and insulated terminals.
After repairs, clear codes, perform functional test of defogger operation and re-scan to confirm no return of B1346. Monitor for parasitic drain if circuit was powered with ignition OFF.
Safety: disconnect battery before performing major harness repairs to avoid shorts and injury.

Backlite relay control circuit wire chafed and contacting a battery-fed conductor
Backlite input connector pin pushed into another terminal supplying battery voltage
Switch or relay welded internally causing continuous battery feed to input circuit
Fuse or fusible link bypassed or bridged, feeding battery voltage into the input circuit