If your 1999 Pontiac Firebird won't turn over, you must troubleshoot the ignition system. Four key components force the engine to turn over. The battery, ignition switch, starter motor and starter solenoid all play an important part of turning the engine crankshaft. If you engine doesn't even turn over, the likely cause is one of these parts. Troubleshooting, starting with the battery, will lead you to a quick resolution of your issue.
Place the black lead of your multimeter onto the negative battery terminal and then place the red lead of the multimeter onto the positive battery terminal. Turn the meter to 20V and inspect the Firebird's battery output. If it reads less than 12 volts, charge the battery. If it is more than 12 volts, or the Firebird still does not start after charging, move to the next step. The battery is not the issue.
Turn on the Firebird's headlights so you can test the ignition switch. With the headlight on, turn the ignition key. If the headlights do not dim, the ignition key does not send electricity to the starter motor and the starter solenoid. The switch is defective. If the lights do dim, the switch works. Move to the next step in the process.
Locate the starter motor under the motor, bolted to the transmission housing on the driver's side. On top of the starter motor, you will locate the starter solenoid.
Place a metal screwdriver across the two metal wire contacts on the back of the starter solenoid. This prevents the solenoid from kicking the starter gear into the transmission housing. However, with the solenoid disabled, when you attempt to start the Firebird, the starter motor should turn on.
Tell to the second person to start the engine while you have the screwdriver across the two metal contacts. Listen to the starter motor. If the starter motor turns on and makes a humming sound, the starter motor is fine and the solenoid is defective. If the starter motor fails to turn on or the humming sound is choppy. The starter motor is defective and the solenoid is fine.
