B1492

Code

FIAT B — Body

Ignition cylinder sensor open circuit

Brand: FIAT

Type: B — Body

Views: UK: 3 EN: 4 RU: 3

AI status

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Page language: EN

Broken or disconnected wiring between ignition cylinder sensor and control module
Corroded or bent connector pins at ignition lock or module
Failed ignition cylinder sensor (internal open circuit)
Water ingress or contamination in the lock assembly / connector
Blown fuse or loss of reference/ground to the sensor
Damage from steering column repair, aftermarket alarm/immobilizer installation or impact

MIL/airbag/immobilizer warning light or specific instrument cluster warning
No crank or intermittent starter operation
Key position not recognized (accessory/on/start) or random loss of key functions
Vehicle may fail immobilizer checks or refuse to start
Possible intermittent operation when wiggling key or turning steering column

Read and record all related codes and freeze frame data with a diagnostic scanner
Inspect ignition lock area, harness and connectors for corrosion, damage or water
Verify fuses and power/ground to the circuit feeding the ignition cylinder sensor
Perform continuity/resistance check of the sensor wiring (pin-to-pin) with connector disconnected
Measure sensor reference voltage and signal while turning key through positions
Wiggle test wiring while monitoring signal to reproduce the fault

Reference supply: typically ~5 V (check vehicle wiring diagram for exact value)
Signal: changes with key position, expected ~0.2 V (OFF) up to ~4.8 V (ON/START) depending on design
Open-circuit condition: infinite resistance; signal reads no continuity or signal missing
Typical continuity: low ohms between sensor signal and module pin when connected; open if wires broken

Retrieve DTCs and note any other related codes (immobilizer, CAN communication, power/ground faults).
Visually inspect the ignition cylinder, connector and wiring for damage, corrosion, pin deformation or water ingress.
With ignition off, disconnect sensor connector and check for bent/missing pins and secure mating at both ends.
Check fuses and verify sensor reference power and ground at the connector (use wiring diagram to identify pins).
With connector connected, back-probe the signal wire and measure voltage while rotating the key through OFF/ACC/ON/START — confirm expected changing voltage. If no signal, proceed.
Perform continuity test between the sensor signal pin and the receiving module pin. Repair any open circuits found.
If wiring and connectors are good but signal is absent or out of range, bench-test or replace the ignition cylinder sensor assembly per service manual.
After repair, clear codes and perform functional test and road/start cycles to confirm fault does not return.
If intermittent or communication-related faults persist, inspect related modules and CAN/bus connections and test for loss of communications or module faults.

⚠️ Status

Ignition cylinder sensor circuit open — no valid signal detected from ignition lock sensor.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours

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