FixItFor.Us
P codepowertrainMedium severity

P0616Starter Relay Circuit Low

The starter relay control circuit is stuck at a lower voltage than the engine computer expects.

Definition

The PCM monitors the starter relay control circuit and expects defined voltage levels in the relay's off and commanded states. P0616 sets when the circuit reads low when it should not — typically a short to ground in the control wire, a shorted relay coil, or a stuck-on driver. Depending on the design, the result is either a no-crank condition or, in the worst case, a starter that engages or stays engaged when it should not, which can destroy the starter and flexplate. The code should be diagnosed promptly for that reason.

Common causes

  • Starter relay control wire shorted to ground
  • Shorted starter relay coil pulling the circuit low
  • Corroded or water-contaminated connector grounding the control circuit
  • Chafed harness where it routes near the engine block or body panels
  • Faulty PCM driver stuck in the on (grounded) state

Common misdiagnoses

  • Replacing the starter motor for a circuit-side fault
  • Replacing the ignition switch without testing the relay control wire
  • Replacing the battery for a no-crank with normal battery voltage
  • Condemning the PCM before checking the harness for a short to ground

Troubleshooting steps

  1. 1.Measure the control circuit voltage key-on

    With the relay installed and the key on (not START), the control circuit should sit at its specified rest voltage; near 0 V indicates the short-low condition.

  2. 2.Isolate the relay from the wiring

    Remove the relay and re-measure: if the low reading disappears, the relay coil is shorted; if it persists, the fault is in the harness or PCM.

  3. 3.Test the control wire for a short to ground

    With the relay and PCM disconnected, measure resistance from the control wire to chassis ground; a low reading confirms a harness short to locate and repair.

  4. 4.Inspect harness routing and connectors

    Trace the circuit for chafe points, water intrusion, and rodent damage, paying attention to areas near the starter and along the frame rail.

  5. 5.Verify the repair

    Reassemble, clear the code, and confirm normal cranking plus no code reset across several key cycles.

Related codes