PCM Controlled Generator Diagnosis

Schematic:

CIRCUIT DESCRIPTION
The generator communicates to the Powertrain Control Module (PCM) over one line, the L or lamp circuit. The PCM uses the L circuit to monitor faults in the charging system. The generator L terminal indicates whether the PCM is allowing the generator to operate. The PCM can disable the generator under certain conditions in order to ease starting. Active indicates that the PCM is allowing generator operation, while inactive indicates that the PCM is not allowing generator operation.

DIAGNOSTIC AIDS
^ An Intermittent problem may be caused by a poor connection, rubbed through wire insulation, or a broken wire that inside the insulation.
^ Any circuitry, that is suspected as causing the intermittent complaint, should be thoroughly inspected for the following items:
- Improper mating
- Broken locks
- Poor terminal to wiring connections
- Physical damage to the wiring harness

Diagnostic Chart (Part 1 Of 2):

Diagnostic Chart (Part 2 Of 2):

TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table:
4. If the volts telltale lamp is not operating, either a short circuit or the IPC is malfunctioning. This determines whether the L circuit, generator, or IPC is malfunctioning.
5. If the charging system is not functioning, system voltage cannot be maintained above 12 V. Turning OFF all accessories assures that the system voltage is not being drawn down by an accessory that normally draws a large current.
8. If the lamp circuit is not shorted to ground, the volts telltale lamp will go OFF until the next key cycle when the test lamp is probed into terminal B. Be careful not to probe terminal C with the test lamp, this will turn off the volts telltale lamp whether or not the lamp circuit is shorted.
11. The PCM supplies a voltage to the generator. If voltage is available to the generator at this terminal, then the PCM and wiring are OK.
16. The replacement PCM must be programmed and the Crankshaft Position System Variation Learn procedure.