Pcm & Generator Shearing Inspection
- Measure the generator terminal "B" voltage when the electrical loads (Headlights, blower motor, rear window defroster, and brake lights) on and then off. If more than 15 volts exists, go to next step. If less than 13 volts exists, go to step 3.
- Monitor the ALTTV (generator output voltage) PID using Worldwide Diagnostic System (WDS) or equivalent scan tool, or measure the voltage at PCM terminal 2AM using a DVOM. See Fig 1. If the voltage is 13-15 volts, go to step 4. If voltage is not 13-15 volts, check PCM input error.
- Monitor the ALTTV (generator output voltage) PID using Worldwide Diagnostic System (WDS) or equivalent scan tool, or measure the voltage of PCM terminal 2AM using a DVOM. See Fig 1. If voltage is 13-15 volts, go to step 5. If voltage is not 13-15 volts, check PCM input error.
- Using scan tool, monitor the ALTF (generator field coil control duty value) PID, or calculate the duty value of the PCM terminal 2AQ using a oscilloscope. See Fig 2. If the duty value is 100 percent, check for PCM input error. If duty value is not 100 percent, PCM and/or generator may be faulty.
- Using scan tool, monitor the ALTF (generator field coil control duty value) PID, or calculate the duty value of the PCM terminal 2AQ using a oscilloscope. See Fig 2. If the duty value is zero percent, check PCM input error. If the duty value in not zero percent, PCM and/or generator may be faulty.
NOTE:
If the generator field coil duty value does not change when electrical loads (headlights, blower motor, rear window defroster , brake lights etc.) are on or off, inspection with discharged battery is needed.