1. Battery Issues:
* Dead or weak battery: The most common cause. Test the battery voltage with a multimeter. It should read around 12.6V when fully charged. A lower reading indicates a weak or dead battery.
* Loose or corroded battery terminals: Check the terminals for corrosion and ensure they are clean and tightly connected to both the battery and the cables.
2. Wiring Problems:
* Broken or corroded wires: Inspect the wiring leading to the starter, including the main power cable from the battery, the ignition switch wiring, and the ground wire. Look for breaks, fraying, corrosion, or loose connections. Pay close attention to the area where the wires connect to the starter solenoid.
* Bad starter solenoid: The solenoid is an electromagnet that engages the starter motor. Internal failure can prevent power from reaching the starter. A clicking sound when you turn the key is often a sign of a failing solenoid.
* Faulty ignition switch: This switch controls the power flow to the starter. A malfunctioning switch can prevent the starter circuit from completing.
* Neutral Safety Switch (NSS): This switch prevents the starter from engaging unless the transmission is in park or neutral. A faulty NSS will prevent the starter from receiving power.
* Poor ground connection: A poor ground connection anywhere in the circuit will disrupt the flow of electricity to the starter. Check the ground strap from the engine to the chassis for corrosion or looseness.
3. Fuses and Circuit Breakers:
* Blown fuse or tripped circuit breaker: Check the fuse box for any blown fuses related to the ignition system or starter circuit. Some older vehicles might use a circuit breaker instead of a fuse.
4. Starter Motor Issues (Less Likely if no power at all):
* While less likely to cause a complete lack of power, a completely dead starter motor *could* prevent a current from flowing through the entire circuit (though you'd still likely see some voltage drop across the circuit).
Troubleshooting Steps:
1. Check the battery: Test voltage. Jump-start the car to rule out a weak battery as the problem.
2. Check the battery terminals: Clean and tighten them.
3. Inspect wiring: Carefully examine all wiring related to the starter for damage or corrosion.
4. Check the fuses and circuit breakers: Replace any blown fuses or reset any tripped breakers.
5. Test for power at the starter solenoid: Use a multimeter to check for power at the large terminal on the starter solenoid when the ignition is turned to the "start" position. If no power is present here, the problem lies before the solenoid (battery, wiring, ignition switch, NSS, fuses).
6. Check for power at the ignition switch: This requires some electrical knowledge and the correct wiring diagram for your Trans Am. It's usually easier to work backward from the starter to the source of power.
If you're not comfortable working with automotive electricity, it's best to take your Trans Am to a qualified mechanic for diagnosis and repair. Working on the electrical system can be dangerous if not done correctly.
