* Ignition Switch: A faulty ignition switch can prevent power from reaching the ignition system components, including the coil and module. Test the switch for proper power output in different ignition positions.
* Wiring: Broken, corroded, or poorly connected wires anywhere in the ignition system are very common causes of no spark. Inspect all wires leading to and from the coil, module, distributor, and ignition switch. Pay close attention to connections and look for any signs of damage. A wiring diagram will be helpful here.
* Distributor Cap and Rotor: These components distribute the high voltage to the spark plugs. Worn, cracked, or corroded caps and rotors can prevent spark. Inspect for any visible damage or carbon tracking.
* Pick-up Coil (in Distributor): This coil in the distributor senses the position of the rotor and triggers the ignition module. A faulty pick-up coil will prevent the module from sending the signal to fire the coil. Testing this requires an ohmmeter.
* Crankshaft Position Sensor (CMP Sensor): Some 1987 Bronco IIs might use a CMP sensor (depending on the engine). This sensor tells the computer the engine's rotational position, influencing ignition timing. A faulty sensor could prevent a spark signal. This requires testing with a multimeter or scan tool.
* Ignition Control Module (Even Though Replaced): It's possible the *new* module is defective. While less likely, it's a possibility to consider. Return it for testing or replacement if possible.
* Computer/ECU (PCM): The PCM controls many aspects of the ignition system. A faulty PCM could prevent spark generation. Diagnosing this typically requires a scan tool.
* Insufficient Fuel Pump Pressure: While this seems unrelated to spark, a no-start situation could also be due to a lack of fuel, and you'll be chasing spark issues when the problem is elsewhere.
Troubleshooting Steps:
1. Visual Inspection: Thoroughly inspect all wiring, connectors, the distributor cap and rotor for any obvious damage.
2. Power Checks: Use a multimeter to test for power at the coil's positive terminal when the ignition is turned on. If no power, trace back the wiring toward the ignition switch.
3. Continuity Tests: Use a multimeter to check for continuity in the wiring between the ignition switch, coil, module, and distributor. A wiring diagram is essential here.
4. Distributor Tests: If you have access to a test light or multimeter, check for continuity and voltage on the pick-up coil inside the distributor.
5. Testing the coil and module with a multimeter (this needs to be done based on the specific testing instructions for your vehicle's components): This checks for proper resistance values. There are detailed procedures online for testing these components.
6. Consult a Repair Manual: A Haynes or Chilton repair manual specific to your 1987 Ford Bronco II will provide detailed wiring diagrams and testing procedures.
Start with the simpler checks (visual inspection, power checks, and wiring) before moving to more complex component testing. If you're not comfortable working on automotive electrical systems, it's best to take the vehicle to a qualified mechanic. Troubleshooting ignition systems requires patience and a systematic approach.
