What this code means
P0615 may indicate that the PCM is seeing an unexpected signal on the starter cut relay diagnosis circuit while starter operation is being commanded.
What the vehicle may do
- The vehicle may not crank or may not start.
- The engine may still start while the PCM detects an issue in the starter cut relay feedback or control-related circuit.
- The warning may be intermittent if the circuit or connector condition changes with vibration, temperature, or load.
Possible fault areas
- Possible starter cut relay circuit issue.
- Possible relay circuit board or connector issue.
- Possible wiring issue between the relay circuit and PCM.
- Possible power supply issue for the starter cut relay circuit.
- Possible PCM-side issue after the external circuit checks are normal.
Diagnostic path
Opening context
On this Civic, P0615 points to the PCM watching the starter cut relay diagnosis circuit and seeing something that does not match what it expects while the starter is commanded on. The driver may see a no-crank or no-start complaint, or the engine may still start while the PCM flags the starter cut relay feedback side. Broadly, this can involve the starter cut relay circuits, the relay circuit board side, wiring between the relay circuit and PCM, connector condition, power supply to the circuit, or a possible PCM-side fault. Start with the basic system checks, then follow a structured diagnostic approach so you do not chase the wrong side of the circuit.
Handle related starter cut relay faults first
Before you focus on P0615 by itself, look for any other starter cut relay faults or indicated starter cut relay systems. If those are present, check what they mean first. That matters because a related starter cut relay problem can steer the rest of this diagnosis and may explain why P0615 set.
Confirm the symptom and choose the path
Next, confirm the condition by trying to start the engine. The first split is simple: does the engine start or not? If it does not start, stay on the no-start circuit inspection path. If it does start, move to the open-wire inspection path for the relay-to-PCM side. Keep the paths separate, because the test direction depends on the actual vehicle behavior.
No-start path: starter cut relay circuit voltage check
If the engine does not start, inspect the IG1_ST_CUT_RLY and IG1_STARTER_CUT circuit. Disconnect relay circuit board connector B, the 12-pin connector, then test the disconnected female terminals with IG Mode ON. A normal result for this circuit type is 12 V battery voltage. If that inspection is abnormal, treat it as a circuit problem. If the power supply part of the table is abnormal, continue with the additional power supply inspection to locate the failure.
Before disconnecting the PCM connector
Before you disconnect the PCM connector for the open-wire inspection, jump the SCS line with the HDS and wait more than 1 minute. Do not skip that setup step. Also make sure the connector and terminal locations are positively identified before probing. If the terminal identification is not clear, pause, recheck the earlier diagnostic path, and avoid guessing.
Engine-starts path: relay-to-PCM open-wire inspection
If the engine starts, perform the ST_RLY_1_TO_2 open-wire inspection. Disconnect relay circuit board connector B, the 12-pin connector, and PCM connector A, the 50-pin connector. With IG Mode OFF, check the disconnected female terminals. A normal result is less than 1 Ω. If the inspection is abnormal, there is a problem in the circuit.
PCM inspection and wrap-up
If the other inspection items all show normal, then continue with the PCM inspection. At that point, the diagnostic path has narrowed away from the external circuit checks and points to a PCM problem. Keep verification separate from the circuit testing: after the fault path is addressed, verify the repair and confirm P0615 stays gone. The takeaway is to let the start-or-no-start condition choose the path, prove the circuit results, and only move toward the PCM after the earlier inspections are normal. For more diagnostic training, visit stepdiagnostics.com.
Final check
P0615 diagnosis often depends on first confirming whether the engine starts, then following the correct circuit test path before considering a PCM-side problem.
For more guided automotive diagnostics, visit STEP Diagnostics.
