B1363

Code

Other B — Body

Ignition Start Circuit Failure

Brand: Other

Type: B — Body

Views: UK: 20 EN: 37 RU: 27

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Page language: EN

Causes

Blown fuse protecting ignition/start circuit
Open or shorted wiring between ignition switch, relay, BCM/PCM and starter solenoid
Faulty ignition switch or key cylinder
Failed starter relay or starter solenoid
Poor or corroded connector or ground at starter/relay/module
Body control module (BCM)/PCM fault or lost communication

Symptoms

No‑crank or intermittent crank when turning key to START
Starter click without engine turnover
Accessory or dash items powered but engine will not crank
Malfunction indicator or security/immobilizer lamp illuminated
Cranking only with jump start or multiple attempts

What to check

Verify battery voltage (resting and while cranking) and battery terminals are clean/tight
Inspect and test ignition/start fuses and starter relay
Visually inspect wiring harness, connectors and ground points for corrosion, damage or looseness
Use a scan tool to read B1363 and look for related communication/security/immobilizer codes
Measure voltage at starter control terminal (relay output and starter solenoid input) while attempting to start
Check continuity between ignition switch, relay coil, BCM/PCM and starter solenoid

Signal parameters

Key OFF: ~0 V on START circuit control line
Key ON (RUN): accessory circuits ~12 V (vehicle dependent)
Key START: control line to starter relay or starter solenoid commanded to battery voltage (~11–14 V) while cranking (voltage drop under load should be limited)
Starter solenoid coil: low resistance (manufacturer specific; typically a few ohms) — verifies coil continuity
CAN/Circuit messages: the BCM/PCM should report key/immobilizer and start request messages on bus (no lost‑comm faults)

Diagnostic algorithm

Safety first: park in gear/park, set parking brake, remove loose jewelry and use insulated tools when working near battery/starter.
Step 1 — Battery and basics: measure battery resting voltage and voltage while attempting to crank; confirm >11.5 V under load. Clean battery terminals.
Step 2 — Fuses/relay: inspect and test fuses and the starter/ignition relay; swap with known good relay if applicable.
Step 3 — Visual/wiring: inspect connectors at ignition switch, BCM/PCM, starter relay and starter solenoid for corrosion, pin damage or loose mates.
Step 4 — Control voltage: with a helper, monitor voltage at the relay control terminal and at the starter solenoid input while turning key to START; no control voltage indicates upstream fault (switch/BCM/immobilizer).
Step 5 — Continuity/grounds: with ignition OFF and battery isolated where required, check continuity from ignition switch to relay and from relay to starter solenoid; check ground straps and chassis grounds for low resistance.
Step 6 — Module/communication: check for U‑codes or lost communication with scan tool; verify immobilizer recognizes the key and is not inhibiting start.
Step 7 — Component substitution/repair: if wiring and control signals are correct but starter/solenoid or relay fail bench tests, replace component. Repair or replace wiring/connectors/relays as required.
Step 8 — Confirm: clear codes, verify proper operation through multiple start cycles and re‑scan for recurrence.

Likely causes

Blown or loose fuse on ignition/start circuit
Corroded connector or broken wire at starter relay or starter solenoid
Failed starter relay or starter solenoid
Faulty ignition switch or worn key/immobilizer antenna
Loss of comm from BCM/PCM to starter control

Fault status

⚠️ Status

Ignition start circuit failure — control signal open/short or communication/security inhibition detected; starter commanded state not verified or unexpected voltage present.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.5 hours