- Diagnostic Procedure

DEFINITION
The problem may or may not turn ON the Malfunction Indicator Lamp (MIL) or store a Diagnostic Trouble Code (DTC).

PRELIMINARY CHECKS

^ Refer to Important Preliminary Checks. Testing and Inspection
^ Do not use the DTC tables. If a fault is an intermittent, the use of DTC tables may result in the replacement of good parts.

FAULTY ELECTRICAL CONNECTIONS OR WIRING
Faulty electrical connections or wiring can cause most intermittent problems.

^ Check the suspected circuit for the following conditions:

- Connectors poorly mated
- Terminals not fully seated in the connector body (backed out)
- Terminals improperly formed or damaged
- Terminal to wires poorly connected

^ Carefully reform all the connector terminals in the problem circuit in order to ensure the proper contact tension. If necessary replace all the connector terminals in the problem circuit in order to ensure the proper contact tension.
^ Checking for poor terminal to wire connections requires removing the terminal from the connector body in. Refer to the Wiring Repairs in Engine Electrical. Electrical Diagrams

ROAD TEST
If a visual and physical check does not locate the cause of the problem, drive the vehicle with a J 39200 connected to a suspected circuit or use a scan tool.

When the problem occurs, an abnormal voltage or scan reading indicates the problem may be in that circuit.

INTERMITTENT MALFUNCTION INDICATOR LAMP (MIL)
The following components can cause an intermillent MIL and no DTC(s):

^ A defective relay, Control Module driven solenoid, or a switch that can cause an electrical system interference. Normally, the problem will occur when the faulty component is operating.
^ The improper installation of electrical devices, such as lights, 2-way radios, electric motors, etc.
^ Route the Ignition Control (IC) wires away from the spark plug wires, ignition system components and the generator. The wire for the engine ground from the Control Module to the ignition system should be a good ground.
^ The ignition secondary voltage shorted to a ground.
^ The Malfunction Indicator Lamp (MIL) circuit or the Diagnostic Test Terminal intermittently shorted to a ground.
^ The Control Module grounds.

LOSS OF DTC MEMORY

1. In order to check for the loss of the DTC Memory, disconnect the Throttle Position (TP) sensor.
2. Idle the engine until the Malfunction Indicator Lamp illuminates.
3. The Vehicle Control Module (VCM) should store a Throttle Position DTC.
4. The Throttle Position DTC should remain in the memory when turning off the ignition.
5. If the Throttle Position DTC does not store and remain, the Control Module is faulty.

ADDITIONAL CHECKs
Check for an open diode across the A/C compressor clutch and for other open diodes. Refer to the Wiring Diagrams. Electrical Diagrams