What it means
The ignition switch run/start-position circuit signal is above the expected limit. The code does not establish the switch state or resulting behavior.
At a glance
- Usually lights the check-engine light
How it works
The ignition switch sends a run/start signal to the receiving module when the key or start control is in Run or Start. P2535 sets when that monitored signal rises above its expected limit, which can happen if the On/Start wire contacts battery voltage; it does not establish the actual switch position.
Common causes
Most likely first.
- On/Start wire shorted to battery voltage
- Connector pins corroded - high contact resistance
- Supply wire pinched against B+ source
Symptoms
- Check-engine or electrical-system warning light
- Starting or engine operation may be inconsistent
- Run/start accessories may remain powered unexpectedly
How to diagnose it
- Record freeze-frame data and determine whether the high signal appeared with the key off, in Run, during cranking, or while driving.
- Compare scan-tool run/start status with the selected key position and check for related electrical faults.
- Inspect the On/Start harness for pinching against a battery-positive feed, damaged insulation, and corroded or loose connector pins.
- With the wiring diagram, test whether the circuit is shorted to battery voltage and check switch output against the manufacturer's specification.
- If no harness short is found, verify the receiving module connector and input before diagnosing a module fault.
Common fixes
- Repair or reroute a pinched On/Start wire that is contacting a battery-positive source.
- Clean and secure corroded or loose connector pins.
- Repair damaged wiring or a short between the run/start circuit and a supply wire.
- Replace a faulty ignition switch or repair the receiving module circuit only after confirming the source of the high signal.
Can I keep driving?
Unexpected run/start signal behavior can cause inconsistent starting or engine operation, and accessories may stay powered after shutdown. If the engine stalls or the vehicle will not shut down normally, stop in a safe place and have the fault diagnosed.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.