How are Distributor Assembly issues diagnosed?
Diagnostics will take one of two paths for a distributor, mechanical or electrical. If the distributor is suspected of mechanical failure, including failure of the vacuum canister, mechanical advance, bearing, or drive shaft, the distributor may be inspected in or out of the engine. The vacuum advance canister can be tested with a vacuum gauge to ensure there are no leaks in the diaphragm. If damage to the ignition distributor drive shaft is suspected, it must be removed and inspected. Electrical diagnosis begins by testing the ignition coil in most cases, and if the ignition coil and primary ignition wire are working correctly, the distributor cap and rotor will be inspected, as well the ignition module. Finally, the pickup coil will be tested for proper resistance across the coil, or proper voltage production when signaling the ignition module to fire. Note, the majority of these components can be replaced individually, but when multiple components are found to be faulty, it may be more economical to replace the ignition distributor assembly.