Diagnostic Test

CHECK FOR AN ACTIVE CONDITION
1. Start the engine and allow it to idle.
2. With the scan tool, read DTCs and record on the repair order.
  Is the DTC active or pending?
  
  Yes
  - Go To 2
  No
  - Perform the INTERMITTENT CONDITION diagnostic procedure. Refer to INTERMITTENT CONDITION .
CHECK THE ALTERNATOR DUTY CYCLE FOR PROPER OPERATION
1. With the scan tool, check the Duty Cycle reading for the Alternator.
  NOTE:
  During normal operation the typical duty cycle of the field control at idle with minimal loads is approximately 35-40%, which will equate to between 4.0 and 5.0 volts. Depending on the charging issue, the PCM can drive the duty cycle to off (0%), which will equate to zero volts, or full field (100%), which will equate to between 11.0 and 12.0 volts.
  
  What is the Alternator duty cycle on the scan tool?
  
  0%
  - Go To 3
  100%
  - Go To 5
CHECK THE (K20) ALTERNATOR FIELD CONTROL CIRCUIT FOR A SHORT TO VOLTAGE
WARNING:
When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts or fan. Do not wear loose clothing. Failure to follow these instructions may result in possible serious or fatal injury.
1. Measure the voltage on the (K20) Alternator Field Control circuit by back probing the Alternator harness connector while the engine is running.
  Is there any voltage present?
  
  Yes
  - Repair the (K20) Alternator Field Control circuit for a short to voltage.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  No
  - Go To 4
CHECK THE ALTERNATOR AND PCM HARNESS CONNECTORS
1. Check the Alternator and PCM harness connectors for conditions that could cause poor terminal contact or voltage leak to other circuits.
  Were any problems found with the harness connectors?
  
  Yes
  - Repair the Alternator or PCM harness connectors.
  - Perform the PCM VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  No
  - Replace the Alternator in accordance with the Service information.
    Refer to GENERATOR, REMOVAL AND INSTALLATION .
  - Perform the PCM VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
CHECK THE ALTERNATOR FIELD CONTROL CIRCUIT VOLTAGE
WARNING:
When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts or fan. Do not wear loose clothing. Failure to follow these instructions may result in possible serious or fatal injury.
1. Measure the voltage on the (K20) Alternator Field Control circuit by back probing the Alternator harness connector with the engine running.
  Is the voltage between 11.0 and 12.0 volts?
  
  Yes
  - Go To 6
  No
  - Go To 7
CHECK THE ALTERNATOR AND PCM HARNESS CONNECTORS
1. Check the Alternator and PCM harness connectors for conditions that could cause poor terminal contact or voltage leak to other circuits.
  Were any problems found with the harness connectors?
  
  Yes
  - Repair the Alternator or PCM harness connectors.
  - Perform the PCM VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  No
  - Replace the Alternator in accordance with the Service information.
    Refer to GENERATOR, REMOVAL AND INSTALLATION .
  - Perform the PCM VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
CHECK THE (K20) ALTERNATOR FIELD CONTROL CIRCUIT FOR AN OPEN/HIGH RESISTANCE
1. Turn the ignition off.
2. Disconnect the Alternator harness connector.
3. Disconnect the PCM C2 harness connector.
  CAUTION:
  Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install the GPEC Diagnostic Adaptor to perform the diagnosis.
4. Connect the (special tool #10436, Adapter, GPEC Diagnostic) to the engine harness side of the PCM C2 harness connector. Do not connect the GPEC Diagnostic Adaptor to the PCM.
5. Measure the resistance on the (K20) Alternator Field Control circuit between the Alternator harness connector and the GPEC Adaptor.
  Is the resistance below 3.0 Ohms?
  
  Yes
  - Go To 8
  No
  - Repair the (K20) Alternator Field Control circuit for an open or high resistance.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
CHECK THE (K20) ALTERNATOR FIELD CONTROL CIRCUIT FOR A SHORT TO GROUND
1. Check for continuity between ground and the (K20) Alternator Field Control circuit at the GPEC Adaptor.
  Is there continuity between ground and the (K20) Alternator Field Control circuit?
  
  Yes
  - Repair the (K20) Alternator Field Control circuit for a short to ground.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  No
  - Go To 9
CHECK RELATED HARNESS CONNECTIONS
1. Disconnect all PCM harness connectors.
2. Disconnect all related in-line harness connections (if equipped).
3. Disconnect the related component harness connectors.
4. Inspect harness connectors, component connectors, and all male and female terminals for the following conditions:
  - Proper connector installation.
  - Damaged connector locks.
  - Corrosion.
  - Other signs of water intrusion.
  - Weather seal damage (if equipped).
  - Bent terminals.
  - Overheating due to a poor connection (terminal may be discolored due to excessive current draw).
  - Terminals that have been pushed back into the connector cavity.
  - Check for spread terminals and verify proper terminal tension.
  Repair any conditions that are found.
5. Connect all PCM harness connectors. Be certain that all harness connectors are fully seated and the connector locks are fully engaged.
6. Connect all in-line harness connectors (if equipped). Be certain that all connectors are fully seated and the connector locks are fully engaged.
7. Connect all related component harness connectors. Be certain that all connectors are fully seated and the connector locks are fully engaged.
8. With the scan tool, erase DTCs.
9. Test drive or operate the vehicle in accordance with the when monitored and set conditions.
10. With the scan tool, read DTCs.
  Did the DTC return?
  
  Yes
  - Replace and program the Powertrain Control Module (PCM) in accordance with the Service Information. Refer to MODULE, POWERTRAIN CONTROL (PCM), REMOVAL AND INSTALLATION .
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  No
  - The wiring or poor connection problem has been repaired.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .