Timing Control Systems

Ignition timing is electronically controlled by Powertrain Control Module (PCM). Base ignition timing is NOT adjustable with this system. PCM controlled ignition system consists of engine coolant temperature sensor, crankshaft position sensor, distributor (except Grand Cherokee), camshaft position sensor, ignition coil, manifold absolute pressure sensor and throttle position sensor. See ENGINE SENSORS, SOLENOIDS & SWITCHES  for component testing.