Pinpoint Test 5: DTC P065B - Generator Control Circuit Range/Performance

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PINPOINT TEST 5: DTC P065B - GENERATOR CONTROL CIRCUIT RANGE/PERFORMANCE

Normal Operation

With the engine running, the PCM expects to receive a valid generator monitor (GENMON) signal with a duty cycle greater than 5% and less than 98%. The PCM also monitors the state of the generator command (GENCMD) signal line to make sure it is not stuck high or stuck low. If the GENMON or GENCMD signal fluctuates between out-of-valid range, or stuck high, or stuck low, or some combination and normal, a DTC will be set. When engine speed rises above approximately 2,000 RPM, the generator will default to a steady voltage of approximately 13.5 volts and the PCM will send a request to the Instrument Cluster (IC) to illuminate the charging system warning indicator lamp

- DTC P065B Generator Control Circuit Range/Performance - If the input frequency was continuously less than 80 Hz or more than 200 Hz the PCM will set this DTC. Additionally, if the signal shows a faulted condition that is happening in a fluctuating manner, the PCM will track the fluctuations between faulted and normal conditions. If the fluctuations occur frequently within a short amount of time, this DTC will also be set.

Possible Causes
- 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.

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