* Worn or Broken Ignition Switch: This is the most probable cause. Over time, the internal components of the ignition switch wear out. The detents (the mechanisms that hold the switch in each position) can become worn, broken, or springy, preventing it from staying in the "run" position. This is a common failure point in older vehicles.
* Broken or Damaged Ignition Switch Wiring: The wires connecting the ignition switch to other parts of the car (like the starter and the ignition system) can become frayed, broken, or corroded. A bad connection or short circuit could interrupt the power flow, causing the ignition to disengage. Check for any obvious damage to the wiring harness near the steering column.
* Steering Column Issues: Sometimes, problems within the steering column itself can interfere with the ignition switch's operation. This might involve issues with the lock cylinder, the steering column lock, or other mechanisms within the column. A binding or damaged steering column can put extra stress on the ignition switch.
* Ignition Cylinder Problems: While less likely to be the direct cause of the switch not staying engaged, a worn or damaged ignition cylinder (the part where the key goes) can put strain on the switch mechanism. A difficult-to-turn key could indicate a problem here.
* Low Battery Voltage (Less Likely): While less probable, an extremely low battery voltage could theoretically cause the ignition system to not receive enough power to hold the switch engaged. However, this usually manifests as other electrical problems as well (dim headlights, slow cranking, etc.).
What to do:
1. Check the Key: Make absolutely sure your key is in good condition and not worn down. A damaged key can struggle to engage the tumbler and put additional stress on the mechanism.
2. Inspect the Wiring: Carefully examine the wiring harness around the steering column. Look for any visible damage, fraying, or corrosion.
3. Try Wiggling the Key: Gently jiggle the key while in the "run" position. If the ignition cuts out, it's a strong indication of a worn ignition switch.
4. Professional Diagnosis: The most reliable way to diagnose the problem is to have a qualified mechanic inspect the vehicle. They have the tools and expertise to test the ignition switch, wiring, and other related components accurately. Replacing the ignition switch is often the solution, but this is a relatively involved repair best left to a professional in most cases due to its location and security implications.
Replacing the ignition switch is a moderately advanced repair and requires some mechanical skill. Unless you're experienced with automotive repairs, it's strongly recommended to have a qualified mechanic handle this. Attempting the repair yourself without the proper knowledge can lead to further damage.
