Code
B1344
FIAT
B — Body
Heated rear window input open circuit
Views:
UK: 3
EN: 7
RU: 6
AI status
Completed
Completed
100%
Causes
- Open wire or connector in heated rear window input circuit (broken/loose connection)
- Faulty/heavily corroded connector or pin at switch, relay or control module
- Failed rear window heater switch or selector (no output)
- Faulty body control module (input circuit)
- Blown fuse or failed relay controlling the heater circuit
- Detached or damaged ground at control module or heater circuit
Symptoms
- Rear window defogger/heater does not activate when selected
- Defogger indicator lamp may not illuminate or may flash
- No clicking from relay when switch is operated
- DTC stored in body/control module relating to heater input open
- Heater works intermittently or only after manipulating connectors
What to check
- Read and record freeze-frame and live data with a diagnostic scan tool; confirm B1344 is current or historical
- Visually inspect fuse(s) and relay(s) for the heated rear window circuit and replace if blown/faulty
- Inspect wiring harness and connectors at the rear window switch, relay/fuse junction and body control module for damage, corrosion, or loose pins
- Operate the rear window heater switch and observe indicator lamp and listen for relay click
- Measure voltage at the switch input and at the connector to the body control module with switch ON and OFF
- Check continuity between switch and control module input; check for short to ground or open circuit
Signal parameters
- Switch input: ~0 V with switch OFF; ~battery voltage (≈12–14 V) with switch ON (measured at the module/switch input pin)
- Control module input: digital/low-voltage signal or switched battery depending on vehicle design — should mirror switch output when healthy
- Heater element current draw when active: typically several amps (usually in the range of 5–20 A depending on vehicle) — verify with clamp meter
- Open circuit indication: infinite/very high resistance or no voltage where voltage is expected
- Expected connector pin voltages and resistances: consult Fiat wiring diagram/specs for exact values
Diagnostic algorithm
- Retrieve and record codes and freeze-frame data with a scan tool; note whether B1344 is current or historic.
- Visually inspect fuses/relays for the heated rear window circuit; replace any blown fuse or suspect relay and retest.
- With ignition ON, operate the rear window heater switch and check for voltage at the switch output terminal; expected ≈ battery voltage when ON. If no voltage, suspect switch.
- Check for voltage at the body control module input pin for the heated rear window signal while operating the switch. If switch output is present but module input is not, inspect/measure continuity between switch and module; repair open or damaged wiring/connectors.
- If there is no output from the switch, remove and bench-test or replace the switch. Inspect connector pins for corrosion or damage.
- Check grounds related to the heater and control module for good connection and low resistance to chassis ground.
- If wiring and switch check OK, test relay activation and measure current to the heater element when commanded ON. If the module does not receive an input but all wiring is intact, consider module fault.
- After repairs, clear the fault code, operate the system through several cycles and confirm the DTC does not return.
- If uncertain, consult Fiat wiring diagrams and pinouts before replacing major components.
Likely causes
- Broken/strained wire to rear window heater switch or module
- Corroded connector pin at switch or central junction block
- Failed heater switch (internal contact open)
- Intermittent connection at relay or fuse box
- Open circuit inside body control module (less common)
Fault status
Status
Open circuit detected on heated rear window input. The control module did not detect the expected input/signal from the rear window heater switch/wiring. Check switch, wiring, fuse/relay and module input.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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