Several things could be causing the smoke:
* Wiring harness fire: This is the most likely and dangerous culprit. The wiring harness in the steering column is complex and susceptible to wear and tear, especially in older vehicles. Chafing against metal, damaged insulation, or short circuits can cause overheating and fire.
* Turn signal switch: The turn signal switch is located within the steering column and can overheat and fail, potentially resulting in smoke.
* Ignition switch: Similar to the turn signal switch, a faulty ignition switch can cause overheating and smoke.
* Column bearing failure: While less likely to cause smoking, a severely damaged column bearing could produce some smoke due to extreme friction. This would probably smell more like burning grease.
* Other electrical components: Other smaller electrical components within the steering column could also be failing and causing smoke.
What you should do:
1. Stop driving the truck immediately. A steering column fire is extremely dangerous.
2. Disconnect the battery's negative terminal. This will help prevent further damage or fire.
3. Inspect the steering column carefully (after disconnecting the battery). Look for any signs of burning, melting plastic, or exposed wires. Try to pinpoint the location of the smoke's origin. Take pictures.
4. Do not attempt to repair it yourself unless you're a qualified auto electrician. The steering column's wiring is complex and working on it incorrectly could worsen the problem or cause injury.
5. Take the truck to a qualified mechanic or auto electrician as soon as possible. Describe the problem clearly, including when the smoking occurred, and any other related symptoms.
The cause needs professional diagnosis to ensure it's fixed correctly and safely. Ignoring this issue could lead to a significant fire hazard and potentially expensive repairs.
