High-Probability Issues:
* Ignition Coil: This is a primary suspect. The coil transforms the low voltage from the ignition system into the high voltage needed for spark. A faulty coil will produce weak or no spark. Testing the coil's resistance (using a multimeter) is crucial.
* Ignition Control Module (ICM) or PCM (Powertrain Control Module): The ICM (sometimes integrated into the PCM) controls the ignition coil's firing. A faulty ICM/PCM will prevent the coil from receiving the signal to create a spark. Diagnosing ICM/PCM issues is more complex and often requires a scan tool to check for trouble codes.
* Crank Position Sensor (CKP): This sensor tells the PCM the position of the crankshaft, which is essential for proper timing of the spark. A faulty CKP will prevent the PCM from triggering the ignition system. Testing involves checking the sensor's output voltage.
* Wiring and Connections: Look for damaged, corroded, or loose wires and connectors throughout the ignition system. Focus on the connections between the ignition coil, ICM/PCM, distributor, crankshaft position sensor, and the battery. A simple loose connection can cause a no-spark condition.
Less Likely, But Possible Issues:
* Distributor Cap and Rotor: While you mentioned the distributor, it's still worth inspecting the cap and rotor for cracks, wear, or carbon buildup. These can prevent proper spark delivery.
* Ignition Switch: A faulty ignition switch can prevent power from reaching the rest of the ignition system.
* Fuse or Relay: Check the fuses and relays related to the ignition system. A blown fuse or faulty relay can interrupt power.
Troubleshooting Steps:
1. Visual Inspection: Carefully inspect all wiring and connections for damage.
2. Check for Codes: Use an OBD-I scanner (appropriate for a 1994 vehicle) to check for diagnostic trouble codes (DTCs) from the PCM. These codes can provide valuable clues.
3. Testing with a Multimeter: Test the ignition coil resistance, and the CKP sensor's voltage output according to factory specifications (found in a repair manual).
4. Component Replacement: If testing reveals faulty components, replace them one by one, starting with the most likely culprits (coil, then ICM/PCM).
Important Note: Working on automotive electrical systems can be dangerous. If you are not comfortable working with electricity, it is best to take your vehicle to a qualified mechanic for diagnosis and repair. A repair manual specific to your 1994 Ford Probe GT will be invaluable in performing these tests.
