B1364

Code

FIAT B — Body

Ignition start circuit

Brand: FIAT

Type: B — Body

Views: UK: 5 EN: 6 RU: 5

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Open or short in ignition start wiring (broken conductor, chafing, pinched cable)
Corroded or loose connector at ignition switch, starter relay or starter solenoid
Faulty ignition switch (start position contact)
Defective starter relay or relay socket
Blown fuse protecting the start circuit
Poor ground or battery negative connection

Symptoms

No-crank or intermittent crank when turning key to START
Starter does not engage but accessories and dash lights work
Clicking from relay/solenoid or no click at all
Engine starts only when tapping starter or wiggling key/harness
Immobiliser/anti-theft warning light or related messages on dash
Random or intermittent no-start conditions

What to check

Scan for stored codes and freeze frame data; note any related U or B codes
Visual inspection of ignition switch, fusebox, starter relay, starter and associated connectors for corrosion, damage or water
Check battery voltage and state of charge (resting and cranking voltage)
Verify fuses and relays for the start circuit (replace or bench-test relay if unsure)
Check continuity and resistance of ignition start feed wiring from switch to relay/solenoid
Measure voltage at ignition switch START terminal with key in START position

Signal parameters

Battery resting voltage: ~12.4–12.8 V (vehicle-specific)
Battery voltage while cranking: typically >= 9.0 V under load (depends on battery/vehicle)
Ignition switch START terminal: battery voltage present only with key in START
Starter relay coil terminal: ~12 V when start command issued; 0 V when not
Starter solenoid control: battery voltage present at solenoid trigger when start commanded
Continuity: low resistance path between ignition switch START terminal and relay coil/solenoid (near 0 Ω through proper connections)

Diagnostic algorithm

Safety: Park secure, engage parking brake and take basic battery safety precautions.
Read codes from all modules; record B1364 and any related codes (immobiliser, BCM, U-codes). Clear codes if appropriate and attempt to reproduce.
Check battery condition and battery terminal connections for corrosion and tightness. Confirm voltage at rest and while cranking.
Inspect fuses and relays in the fuse/relay box for the start circuit. Swap or bench-test suspect relay with known-good unit.
With a test light or DVOM, measure voltage at the ignition switch START terminal while an assistant turns key to START. Confirm battery voltage appears only in START.
Trace/measure continuity from ignition switch START terminal to starter relay coil and to starter solenoid trigger. Repair any open or high-resistance wiring or poor terminal connections.
Probe relay coil and contact terminals: with START command, coil should see ~12 V and relay contacts should pass battery voltage to solenoid. If relay behaves incorrectly, replace.
Check starter solenoid input under cranking attempt; verify solenoid actuates and supplies battery voltage to starter motor. If solenoid/starter draws excessive current or fails to actuate, test/replace starter per service procedure.
Inspect and test immobiliser/key transponder function and related antenna/module if vehicle shows immobiliser errors or if start signal is blocked. Try a known-good programmed key if available.
If wiring, relays, battery and starter are good but fault persists, inspect BCM/engine control module connections and communication lines (CAN); consider module diagnostic data and software updates.
After repairs, clear fault codes and perform repeated start tests to confirm repair. Document findings and replaced parts.

Likely causes

Faulty ignition switch or start-contact inside switch
Open/ intermittent wire between ignition switch and starter relay/solenoid
Defective starter relay or blown fuse in start feed
Poor ground or battery connection causing low voltage to start circuit
Immobiliser not releasing start circuit (key transponder, antenna or module issue)

Fault status

⚠️ Status

Ignition start circuit fault — start signal missing, open or shorted; check ignition switch, wiring, relay, starter and immobiliser.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours

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