Circuit Description
The L-terminal circuit 225 is a two-way link between the PCM and generator.
The PCM supplies the generator with 5 volts whenever the ignition is On.
The PCM will not supply 5 volts to the generator during engine cranking if
battery voltage is below 9.6 volts. Once the engine is running, the generator
must have the 5 volt supply to charge. If the generator stops charging while
the engine is running, it will ground this 5 volt supply from the PCM. When
the PCM detects this ground, it will send a message to the I/P cluster over the Class II
link to illuminate the Charge telltale. The PCM determines electrical system load
by monitoring the generator pulse width modulated (PWM) output on the F-terminal circuit 23.
Conditions for Setting the DTC
| • | DTC P0622 will set if generator F-terminal duty cycle is less than
5% when: |
| - | Condition exists for longer than 30 seconds |
| - | Engine speed is between idle and 3000 rpm |
| • | DTC P0622 will set if generator F-terminal duty cycle is greater
than 65% when: |
| - | Condition exists for longer than 5 seconds |
| • | DTC P0622 diagnostic runs continuously with ignition On. |
| • | P0622 is a (type D) DTC |
Diagnostic Aids
If DTC P0621 is also set, diagnose that DTC first. The generator will
output a 0% duty cycle if it does not have 5 volts at the generator L-terminal
while the engine is running.
If a low circuit fault occurs in the F-terminal circuit while the engine is
running, the Charge telltale will illuminate, however, the generator will still charge.
This only applies if the L-terminal circuit is functioning properly.
An open/short to ground or short to voltage on circuit 23 will set this
DTC.
GENERATOR F-TERMINAL DC on the scan tool should read near 17% with
ignition On and engine Off.
DTC P0622
