System Diagnosis

NOTE: You will not get a code 88 if you are using the "CHECK ENGINE LIGHT" to diagnose the engine control system. There will be a 2-second bulb check, followed by the codes and ending with a code 55. A code 88 will only be set when using Chrysler's DRB: II Tester. Some other "SCAN" testers may also set a code 88 under certain conditions. Check manufacture equipment for specific instructions.

The self-diagnostic capabilities of this system, if properly used, can greatly simplify testing. If, at any time, the logic module receives an incorrect signal or no signal from either the coolant temperature sensor, charge temperature sensor (turbo), MAP sensor or TPS, Power Loss Light on the instrument panel is illuminated.

This light 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 attempts to compensate for the failure of the particular component by substituting information from other sources. Ideally, this will allow the vehicle to be operated until proper repairs can be made.

If the Power Loss Light 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 trouble codes as they are displayed. Trouble codes may be displayed on the Chrysler Diagnostic Readout Box (C-4805) or to a limited extent be flashed on the Power Loss Light.

Once these codes are known, refer to the trouble codes listed in this article to determine the questionable circuit. Then use the wiring diagrams to locate testing points for each circuit. Test circuits and repair or replace as needed. If the problem is repaired or ceases to exist, the logic module cancels the trouble code after 30 ignition on/off cycles.