1. Faulty Ignition Switch:
* The Problem: The ignition switch has multiple contacts that provide power to different components depending on the key position. If these contacts are worn, corroded, or sticking, they might not provide a consistent connection when the key is released to the "ON" position.
* Diagnosis: Try wiggling the key while the engine is running. If the engine stutters or dies, it points to a faulty switch.
* Solution: Replace the entire ignition switch. This might require removing the steering column cover and the ignition lock cylinder.
2. Faulty Ignition Wiring:
* The Problem: The wiring leading to the ignition switch can become corroded, frayed, or damaged over time. This can interrupt the electrical flow and cause the engine to die.
* Diagnosis: Carefully inspect the wiring leading to the ignition switch for signs of damage. Check the connections for corrosion or loose terminals.
* Solution: Repair or replace any damaged wiring. Clean corroded connections with a wire brush and apply dielectric grease for protection.
3. Faulty Neutral Safety Switch:
* The Problem: This switch is located near the transmission and prevents the car from starting unless it's in park or neutral. If it fails, it might not signal the ignition system that it's safe to start the engine.
* Diagnosis: Check if the car starts when the transmission is in "Neutral" (N). If it does, the neutral safety switch could be at fault.
* Solution: Inspect the neutral safety switch for damage or corrosion. Replace it if necessary.
4. Faulty Starter Relay or Solenoid:
* The Problem: These components act as a switch, allowing the starter motor to draw power from the battery. A faulty relay or solenoid can cause the starter to disengage as soon as the key is released.
* Diagnosis: Listen carefully while cranking the engine. If you hear a clicking sound instead of the starter motor engaging, it might be a faulty relay or solenoid.
* Solution: Replace the starter relay or solenoid.
5. Faulty Ignition Control Module (ICM):
* The Problem: The ICM is responsible for controlling the timing and spark output of the engine. A faulty ICM can cause the engine to die after starting.
* Diagnosis: This is more difficult to diagnose without a code reader or testing equipment. You might need to take it to a mechanic for proper diagnosis.
* Solution: Replace the ICM if found to be faulty.
Remember:
* Safety First: Disconnect the battery before working on any electrical components.
* Professional Help: If you're not comfortable working on electrical systems, it's best to take your car to a qualified mechanic. They have the tools and expertise to diagnose and repair the issue properly.
By systematically checking these components, you should be able to pinpoint the cause of your 1986 Thunderbird Turbo Coupe's starting issue.
