Code
B1365
FIAT
B — Body
Engine start short to positive
AI status
Completed
Completed
100%
Causes
- Damaged wiring harness or rubbed-through insulation allowing contact with constant battery positive
- Faulty starter solenoid or starter motor with internal short to battery
- Faulty ignition switch or start push-button stuck/shorted
- Shorted relay contacts or welded relay supplying constant B+ to the start circuit
- Aftermarket accessory or improper repair bridged to battery positive
- Faulty body/engine control module applying incorrect voltage to the start line
Symptoms
- Engine will not crank when starter should be inactive, or starter engages unexpectedly
- Blown fuse in starter/start circuit or repeated electrical faults
- Battery drain or vehicle not going to sleep due to constant B+ on control line
- Stored multiple related B-codes or communication errors with BCM/ECM
- Intermittent no-start or starter remains engaged after key release
What to check
- Read and record all stored fault codes and freeze frame data; note whether code is current or historic
- Visual inspection of start circuit wiring, connectors, and harness routing for damage, heat marks or pinched sections
- Inspect starter, starter relay, and ignition switch for signs of damage or overheating
- Check fuses and fusible links related to the starter and control modules
- Disconnect battery before performing any high-current wiring repairs; use proper PPE
Signal parameters
- Start command line voltage at rest: ~0 V (no key/start request)
- Start command line voltage during start request: ~B+ (battery voltage ~11–14.5 V while cranking)
- Resistance/continuity from start command pin to starter solenoid: low continuity when activated, open when not
- Insulation/continuity test from start line to chassis: should be high resistance (no continuity) when not commanded
- Cranking current to starter: measured with clamp meter to compare against specification (identifies internal starter faults)
Diagnostic algorithm
- Read DTCs and note freeze-frame/conditions; clear codes and attempt to re-create the fault while observing behavior.
- Perform a careful visual inspection of all wiring from the ignition switch/BCM to the starter/solenoid and related relays; repair any damaged insulation or connectors.
- With key off and battery connected, measure voltage at the start command pin; it should be ~0 V. If B+ present with no request, isolate by disconnecting connectors in the circuit one at a time to find where B+ disappears.
- If short persists, disconnect the starter solenoid and relays to determine whether the short is in the harness or the component. If removing the starter eliminates B+ on the start line, suspect starter/solenoid internal short.
- Inspect and test the start relay and ignition switch: swap with a known-good same-type relay or verify switch continuity under the correct conditions.
- Check connectors for corrosion, bent pins or bridges between pins; repair or replace as needed and ensure proper sealing.
- Perform an insulation resistance or wiggle test while monitoring the start line voltage to find intermittent shorts (use caution to avoid creating sparks).
- If wiring and components check good, consider scanning for BCM/ECM firmware faults and consult technical bulletins; replace control module only after wiring/components are verified.
- After repairs, clear codes and perform several start cycles and a road test to confirm issue is resolved.
Likely causes
- Chafed wire where start command harness passes near chassis or engine components
- Failed starter solenoid with internal short feeding B+ back into control circuit
- Stuck/shorted start relay or ignition switch sending battery voltage when not commanded
- Connector corrosion or pin damage creating unintended continuity to B+
- Previous repair splice incorrectly insulated creating intermittent short
Fault status
Status
Fault stored when the engine start control circuit detects an unexpected connection to positive battery voltage (short-to-B+) on the start command line or related wiring, indicating possible harness damage, faulty starter/relay, or erroneous module output.
Repair difficulty: Medium
Diagnostic time: 0.5-2.5 hours
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