P2535Ignition Switch On/Start Position Circuit High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P2535 means the run/crank input stays active while it should be off. GM's 2025 tables fail it in the TCM after 320 of 400 samples with run/crank true while the ECM reports it inactive, Type A, and in the brake control module (EBCM) when the primary wakeup line stays high for 3 s against the network status, Type B; the 2016 Volt uses more than 6.0 V on the line with run/crank inactive. GM bulletin PIT6396 describes a concrete backfeed: once a new K111 fuel pump driver module goes into 2020–2023 Silverado/Sierra with the 3.0L or 6.6L diesel, about 2 V return on ignition circuit 439 via the wiring of the sensor that detects water in the fuel once the key is off. Ram also lists P2535 for the 2021 1500 eTorque. Ford's BOSS 302S table shows no MIL marker.
- What you may notice
- MIL on, code returns at every key-on after clearing
- Modules stay awake, battery drain
- Likely causes
- LikelyVoltage backfeed from another module (GM K111 fuel pump driver via water-in-fuel sensor circuit)
- PossibleRun/crank relay stuck closed
- PossibleRun/crank wire touching a battery feed
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €0 – €500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.