Ignition Switch On/Start Position Circuit High
What it means
P2535 means the ECM sees an abnormally high voltage on the ignition switch On/Start position circuit — the signal that tells the computer the key is in the run or start position. Because this circuit is part of the starting and power-up chain, a fault can cause hard starting, an intermittent no-start, or stalling. The cause is usually the switch, its wiring, a connector, or a related relay.
Can I keep driving? Maybe — the car often runs, but an ignition-switch circuit fault can cause hard starting, no-start, or stalling, so address it soon.
Real-world scan data
Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.
Common symptoms
What you'll notice
- Check-engine light on
- Hard starting or an intermittent no-crank / no-start
- Occasional stalling
- Accessories or warning lights behaving oddly with the key position
Common causes
Most likely first
- Short-to-voltage in the ignition On/Start signal wiringLikely
- Faulty or worn ignition switchCommon
- Faulty ignition or ECM power relayCommon
- Corroded or loose connector at the switchLess often
- Faulty ECM (least common)Less often
How to diagnose & fix
Work through it in order
- Scan and read freeze-frame data to capture when it sets.
- Inspect and wiggle-test the ignition switch connector and wiring.
- Measure the On/Start signal voltage in each key position (off, run, start).
- Check the related fuses and power relays.
- Replace the ignition switch if it tests faulty; consider the ECM last.
FAQ
Quick answers
Is it safe to drive with P2535?+
Can I just clear P2535?+
Related codes
Read & clear P2535 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.