What it means
Auxiliary ignition switch On/Start input reads stuck low — short to ground or stuck-closed contact. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
At a glance
- Usually lights the check-engine light
How it works
The auxiliary ignition switch sends a Run/Start request from a second operating station to the controller. This code sets when the controller reads the On/Start input as continuously low, which can happen if the signal wire is grounded or the switch circuit is stuck in its inactive state.
Common causes
Most likely first.
- Wire shorted to ground
- Connector pins corroded - high contact resistance
- Harness chafing through insulation
Symptoms
- Auxiliary ignition or start function may be unavailable
How to diagnose it
- Use a scan tool to record freeze-frame data and watch the auxiliary On/Start input while switching the auxiliary ignition on and off.
- Check whether the auxiliary station’s Run/Start function is unavailable and whether the primary ignition still operates normally.
- Inspect the auxiliary switch connector and harness for chafing, moisture, corrosion, pushed-back pins, or a wire contacting ground.
- Using the wiring diagram and manufacturer’s procedure, check whether the input wire is shorted to ground and whether the switch changes the circuit state when operated.
- If the harness and switch pass, test the controller input circuit and connector for a grounded pin or internal fault.
Common fixes
- Clean and secure a corroded or loose auxiliary switch connector, replacing damaged terminals as needed.
- Repair insulation damage where the auxiliary On/Start signal wire is contacting ground.
- Replace a faulty auxiliary ignition switch if it holds the circuit low when disconnected from the harness.
- Repair the controller connector or input circuit if testing isolates the fault there.
Can I keep driving?
The auxiliary start function may not work, though the primary ignition may still operate normally. Avoid relying on the auxiliary station until the circuit is repaired.
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.