P0616: starter relay low voltage is judged in the off state

P0616 detects a ground-short signature on the starter relay's low-side control circuit in the cited GM strategy. The driver is off when this check runs. That state is essential because a low control voltage has a different meaning when the driver is intentionally switched on.

Detection and timing

The controller-specific voltage decision corresponds to a short-to-ground impedance of no more than 0.5 ohm. The table is describing the controller's fault-detection capability, not a safe live-circuit resistance-test procedure.

Eight failures in ten samples, taken every fifty milliseconds, form the documented sample decision. Run/crank voltage must be at least 6.41 volts. This enabling value is lower than the 11 volts used by the nearby P0615 open-circuit monitor, so the two codes need not run under identical supply conditions.

Interpreting a starting event

Record the actual relay command and available supply voltage with the fault. A low reading captured while the output was commanded on does not reproduce the defining off-state mismatch. Similarly, the code is about the relay driver circuit and does not establish that the starter motor's mechanical or high-current path is defective.

A repair should be verified with the off-state circuit diagnostic enabled and passing, followed by the applicable starting-system checks. The source lists Type B over two trips. It supplies no universal relay location, pinout or replacement instruction, and starter control should not be bypassed to reproduce the fault.

Source and applicability

Documented monitors in gm-2025-03a, gm-2025-04b, model year 2025. These are module/calibration examples; vehicle, engine and transmission applicability must be confirmed independently. GM 2025-03a, page 404. GM 2025-04b, page 619.