Code
B1363
FIAT
B — Body
Ignition start circuit
Views:
UK: 4
EN: 7
RU: 4
AI status
Completed
Completed
100%
Causes
- Open or short in ignition start wiring harness
- Faulty ignition switch (START position) or ignition barrel
- Defective starter relay or starter solenoid
- Poor battery connection, low battery voltage or blown fuse
- Bad ground(s) or corroded connector(s) in the start circuit
- Faulty body control module (BCM)/ignition control module or immobiliser/antitheft unit
Symptoms
- No crank when key is turned to START
- Intermittent cranking or starting; sometimes starts normally
- Starter relay not clicking when key turned
- Accessory power present but engine won’t engage starter
- Instrument cluster/immobiliser warning or start-inhibit indicator may be present
What to check
- Verify battery state-of-charge and terminal tightness/corrosion
- Check for blown fuses and fusible links related to START/IGN circuits
- Scan vehicle for additional codes (including immobiliser/BCM/engine control codes)
- Inspect ignition switch connector, harness and starter relay for damage or corrosion
- Check ground straps at engine/chassis and at battery
Signal parameters
- Battery voltage at ignition switch: ~12.4–12.8 V (engine off); >11 V while cranking
- Voltage on START feed at switch in START position: close to battery voltage (
- Continuity between ignition switch START terminal and starter relay coil/starter solenoid
- Starter relay coil resistance: typically tens to hundreds of ohms (refer to service data)
- CAN/LIN messages present if vehicle uses networked start inhibit (verify with scan tool)
Diagnostic algorithm
- Record freeze frame/related codes with a proper scan tool; note any immobiliser or BCM messages.
- Confirm battery voltage and load-test or perform a manual crank test (bench test) to rule out weak battery.
- Visually inspect connectors, fuses and wiring on ignition switch, starter relay, starter solenoid and associated grounds.
- With a DVOM, check for battery voltage at ignition switch INPUT and measure voltage at the START terminal while an assistant turns the key to START. If no voltage, suspect the switch or upstream protection.
- Check continuity between ignition switch START terminal and starter relay coil/starter solenoid. Repair any opens or shorts.
- Probe starter relay coil circuit: verify relay activation voltage at relay coil when key is in START. If coil energises but starter does not engage, check starter solenoid wiring and starter unit.
- If the relay does not energise but wiring is good, bench-test/replace the relay. If relay and wiring are good, inspect BCM/immobiliser outputs and relevant network messages with a capable scan tool.
- Inspect and test starter solenoid and engine grounds. Repair corroded connectors and tighten grounds.
- After repairs, clear codes and perform repeated start tests; confirm code does not return.
- If all wiring, relays, starter and battery check good and code persists, consider module-level diagnosis (BCM/immobiliser) per factory procedures.
Likely causes
- Open/shorted wire between ignition switch and starter relay or BCM
- Failed starter relay or starter solenoid
- Corroded connector at ignition switch, relay or fusebox
- Weak battery or poor battery negative/positive connections
- Faulty ignition switch contacts in START position
Fault status
Status
Ignition start circuit malfunction detected — abnormal/start-inhibit signal or wiring fault in START circuit. Further electrical diagnosis required.
Repair difficulty: Medium
Diagnostic time: 1.0 - 3.0 hours
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