FixItFor.Us
P codepowertrainMedium severity

P0615Starter Relay Circuit

The engine computer has detected a general fault in the starter relay control circuit.

Definition

On vehicles where the PCM (or body/theft module) controls starter engagement through a relay, the module monitors the relay control circuit for correct voltage in both the commanded-on and commanded-off states. P0615 sets when the circuit shows an open, an unexpected level, or feedback that does not match the command. The typical symptom is an intermittent or complete no-crank condition, though the code can also be stored with no symptom if the fault is transient. The engine runs normally once started, and the MIL may or may not be commanded on depending on the manufacturer.

Common causes

  • Failed starter relay or corroded relay socket terminals
  • Open or chafed wiring in the relay control circuit
  • Blown fuse feeding the starter relay circuit
  • Faulty ignition switch or park/neutral (transmission range) switch input preventing a valid crank request
  • Anti-theft/immobilizer system blocking the crank signal
  • Faulty PCM relay driver (least common)

Common misdiagnoses

  • Replacing the starter motor when the relay control circuit is the fault
  • Replacing the battery for a no-crank with a healthy, fully charged battery
  • Replacing the neutral safety switch without testing the relay circuit itself
  • Replacing the ignition switch before checking the relay and its wiring

Troubleshooting steps

  1. 1.Verify the symptom and scan all modules

    Attempt a start and note whether the starter clicks, cranks, or does nothing, and check for companion theft/immobilizer codes that would block cranking.

  2. 2.Test the starter relay and socket

    Bench-test the relay (coil typically 50-120 ohms, contacts close at 12 V) and inspect the socket for heat discoloration or corrosion.

  3. 3.Check power and control sides of the circuit

    Verify battery voltage at the relay feed and confirm the control terminal changes state when the key is turned to START in Park.

  4. 4.Confirm the crank request inputs

    Watch the scan tool for ignition-switch START and transmission range (P/N) PIDs while turning the key, since a missing input keeps the PCM from grounding the relay.

  5. 5.Test wiring to the PCM and starter solenoid

    Check the control wire for opens and shorts, and verify voltage reaches the starter solenoid S-terminal when the relay closes.

Related codes