Pinpoint Test 3: DTC P0620 - Generator Control Circuit

PINPOINT TEST 3: DTC P0620

Normal Operation

The PCM monitors the generator output via the GENMON circuit. The PCM uses the GENCOM circuit to command the generator to either increase or decrease output. If the GENCOM circuit (generator control circuit) or the A sense circuit are open or shorted to ground, the PCM will be unable to control the generator output. When the engine speed rises above approximately 2,000 rpm, the generator will default to a steady voltage output of approximately 13.5 volts and the PCM will send a request to the Instrument Cluster (IC) to illuminate the charging system warning indicator. A GENCOM circuit fault can be confirmed by viewing the PCM PID generator command line fault (GENCMD_LF) (YES status indicator fault).

- DTC P0620 (Generator Control Circuit) - If the GENCOM circuit or A sense circuit are open or shorted to ground, the PCM will set this DTC.

Possible Causes
- Fuse
- Wiring, terminals or connectors
- Radial arm adapter
- Generator
- PCM

Diagnostic Procedure

NOTE:Make sure battery voltage is greater than 12.2 volts prior to carrying out this pinpoint test.
NOTE:Do not have a battery charger attached during vehicle testing.