P2535: Run/start input stays high after the reported run/crank state becomes inactive

P2535 identifies inconsistent high ignition run/start information in the reviewed GM module strategies. The code does not necessarily mean that a mechanical ignition switch is defective; the monitored relationship includes a hardwired input and communicated engine-controller state.

Two documented implementations

In the transmission controller, failure means run/crank input remains true while the ECM reports run/crank inactive. The TCM requires 280 failures out of 280 samples at 25-millisecond intervals, with Type A, one-trip behavior.

The brake-controller version instead specifies a hardwired ignition input above 4.5 V while the engine-controller CAN run/crank status is low. That row uses a 2.5-second decision and Type B, two trips. These limits must remain associated with their reporting modules.

Context distinguishes a fault from normal operation

A high input during a valid active ignition state is expected context, not the discrepancy these checks describe. Capture the transition and both representations of run/crank state rather than testing the input at an arbitrary moment.

Identify the storing module before choosing a test procedure. An input-to-message mismatch does not establish whether the physical circuit, switch path or status information is responsible. The TCM enable-column wording also calls its enable a low-circuit diagnostic; that label should not be used to select an electrical test by itself.

Verification should establish consistent input and reported state across the applicable transition and no returning fault after the appropriate monitor completes. No part replacement is established by this summary.

Source and applicability

Confirm the reporting module, system and calibration before applying these diagnostic limits. GM diagnostic table, PDF page 37. GM diagnostic table, PDF page 1168.