System Diagnosis

The self-diagnostic capabilities of this system, if properly utilized, can greatly simplify testing.

If, at any time, the logic module receives an incorrect signal or no signal from either the Coolant Temperature Sensor, MAP sensor or TPS, a Power Loss Lamp on the instrument panel is illuminated. This lamp acts as a warning device to inform the operator that a malfunction in the system has occurred and immediate service is required.

When certain malfunctions occur, the logic module enters the "Limp-In Mode". In this mode, the logic module compensates for failure of components by substituting information from other sources. This allows vehicle to be operated until proper repairs can be made.

If Power Loss Lamp comes on, or if certain driveability or engine performance difficulties exist, the probable source of these difficulties may be determined by entering "On Board Diagnosis" and recording the fault codes as they are displayed.

Once these codes are known, refer to the Trouble Shooting section to determine the questionable circuit. Then use Fig. 5 and Component Connector Identification Charts to locate testing points for each circuit. Test circuits and repair or replace as needed.