Code
P1615
MITSUBISHI
P — Powertrain
Starter fail safe relay
Views:
UK: 15
EN: 32
RU: 20
AI status
Completed
Completed
100%
Causes
- Failed starter fail-safe relay (internal coil/contact failure)
- Blown fuse related to starter/relay circuit
- Open, shorted or high-resistance wiring between ECU, relay and starter
- Poor or corroded ground or power connections
- Faulty engine control module (ECM) or relay driver output
- Antitheft/immobilizer preventing starter relay operation
Symptoms
- Engine will not crank or cranks intermittently
- No audible click from starter relay when key is turned
- Starter motor receives no power despite correct starter switch operation
- Bus or system fault messages related to starter/immobilizer on dash
- Starter engages only when relay is tapped or connector reseated
What to check
- Read and record freeze frame and stored DTCs with an OBD-II scanner capable of manufacturer codes
- Verify battery state of charge and battery terminal tightness (>=12.4 V at rest)
- Inspect fuses and fusible links for starter/ECU power circuits
- Visually inspect starter relay, its socket and wiring for corrosion, damage or loose pins
- Check grounds at engine block, starter and chassis for tight, clean connections
- Attempt to operate relay while monitoring voltages/signals (see signal parameters)
Signal parameters
- Battery supply voltage at relay fuse: ~12.4–12.8 V at rest; >=11.5 V during cranking
- Control/driver voltage from ECU to relay coil: 0 V (off) or approximately battery voltage (on) when cranking request present — measure while cranking attempt
- Voltage at starter motor power terminal when cranking: near battery voltage when relay closes
- Coil resistance of relay (bench): typically tens to low hundreds of ohms (manufacturer specific) — compare with known-good relay
- Voltage drop across relay/power connections when cranking: should be minimal (
Diagnostic algorithm
- Verify DTC P1615 is current or stored; note any additional related codes (starter, fuse, immobilizer).
- Confirm battery health and charge. Poor battery can cause relay/ECU faults; correct if needed.
- Inspect fuses and fusible links for starter power and ECU power. Replace any blown fuses and re-test.
- Visually inspect relay, socket and harness for damage, corrosion or loose pins. Wiggle connectors while monitoring for intermittent behavior.
- With key off, remove the relay and bench-test coil continuity and contact switching if a service manual procedure or known-good relay is available. Replace relay if abnormal.
- With backprobe or meter, check for battery voltage at relay supply terminal and for ECU control signal at relay coil terminal while an assistant turns key to START. Record voltages.
- If control signal is present but relay does not engage, replace relay and retest. If relay engages but starter still does not crank, trace power feed to starter and check solenoid and starter motor.
- If no control signal from ECU, inspect wiring between ECU and relay for opens/shorts and check ECU ground/power. Check immobilizer/security system status and related modules.
- If wiring and relay are good but no proper ECU output, perform ECU/driver diagnostics per manufacturer procedures; consider module replacement only after wiring and power verified.
- Clear codes and perform multiple start attempts to confirm repair. Monitor for reoccurrence and related codes.
Likely causes
- Starter fail-safe relay has failed or intermittent contacts
- Loose, corroded or damaged connector at relay or starter
- Blown starter or ECU supply fuse
- Faulty relay driver transistor inside ECM
- Immobilizer or security system interrupting starter enable
Fault status
Status
Starter fail safe relay
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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