Chart C-4C, Distributor Ignition (Di) System Check (Remote Coil)
NOTE:
Test numbers refer to test numbers on diagnostic chart.
- Two wires are checked to ensure that an open is not present in a spark plug wire. 1A) If spark occurs with 4 terminal distributor connector disconnected, pick-up coil output is too low for EST operation.
- A spark indicates the problem must be distributor cap or rotor.
- Normally, there should be battery voltage at "C" and "+" terminals. Low voltage would indicate an open or a high resistance circuit from the distributor to coil or ignition switch. If "C" terminal voltage was low, but "+" terminal voltage is 10 volts or more, circuit from "C" terminal to ignition coil or ignition coil primary winding is open.
- Check for a shorted module or grounded circuit from ignition coil to module. The distributor module should be turned "OFF." Normal voltage should be about 12 volts. If module is turned "ON," voltage would be low, but above 1 volt. This could cause ignition coil to fail from excessive heat. With an open ignition coil primary winding, a small amount of voltage will leak through the module from the "BATT" to "tach" terminal.
- Applying voltage (1.5 to 8 volts) to module terminal "P" should turn module "ON" and tachometer terminal voltage should drop to about 7-9 volts. This test will determine whether module or coil is faulty, or if pick-up coil is not generating proper signal to turn module "ON." This test can be performed by using a DC battery with a rating of 1.5 to 8 volts. The use of test light is mainly to allow the "P" terminal to be probed more easily. Some digital multi-meters can also be used to trigger module by selecting ohms, usually diode position. In this position the meter may have a voltage across its terminals which can be used to trigger module. The voltage in the ohms position can be checked by using a second meter or by checking manufacturer's specifications of tool being used.
- This should turn "OFF" module and cause a spark. If no spark occurs, the fault is most likely in ignition coil because most module problems would have been found before this point in procedure. A module tester (J 24642) could determine which is at fault.