Ignition Switch Run Position Circuit

Possible causes

• CommonWorn ignition switch contacts
• CommonHeavy keyring wearing the switch, or pulling it out of position
• CommonWiring or connector fault at the switch
• PossibleCorroded connector behind the steering column
• PossibleAftermarket alarm, immobiliser or remote start spliced into the circuit
• RareFailed control module input

What you might notice

• Engine cutting out while driving
• Engine will not start, or starts intermittently
• Electrical accessories cutting in and out
• Dashboard warning lights flickering
• Key feeling loose or vague in the barrel

What to check, in order

1. Take everything except the key off your keyring and see whether the fault changes. A heavy bunch of keys hanging from the barrel wears the switch and can drag it out of the run position over a bump - this is a real and well-documented failure, and it costs nothing to test.
2. Watch the ignition position states on the live data screen while turning the key slowly through each position.
3. Check for a position that reads ambiguously between detents - the classic sign of worn contacts.
4. Inspect the connector behind the steering column.
5. Ask whether an aftermarket alarm or remote start has been fitted.
6. If the engine has cut out while driving even once, treat this as urgent rather than intermittent.