Central Control Module (CCM)

Diagnostic Chart:

Wiring Diagram:

CIRCUIT DESCRIPTION

The (FEDS) Fuel Enable System uses the serial data communication link between the CCM and the ECM to perform a password exchange routine when the ignition is turned "ON." If the password exchange routine is successfully completed, the ECM can pulse the fuel injectors "ON."

If the FEDS Fuel Enable routine is not successfully completed within 2 seconds, DTC 54 will set and both the "SECURITY" and "SYS" indicators will flash together.

TEST DESCRIPTION

Number(s) below refer to circled number(s) on the diagnostic chart.

1. Checks for ECM operation. If the Malfunction Indicator Lamp (MIL) "Service Engine Soon" is not "ON," the ECM may not be available for FEDS exchange for one of many reasons. Perform the "On-Board Diagnostic (OBD) System Check" in "Computers and Control Systems" to determine if there is a problem with the ECM. Testing and Inspection

2. Checks for an ECM DTC 51. If ECM DTC 51 is set, the ECM and/or PROM may have a problem which could prohibit successful FEDS exchange. Repair the ECM DTC 51 condition using the ECM DTC 51 chart in "Computer and Control Systems" before continuing. Computers and Control Systems

3. Checks for CCM DTCs 51, 52 or 53. These DTCs define a problem with the PASS-Key(R) itself or the PASS-Key(R) detection circuitry. If the PASS-Key(R) is not correct, the FEDS exchange will not take place.

4. Checks for a CCM DTC 54 reset after most items that could affect FEDS fuel enable have checked out as OK. If DTC 54 resets, replace the CCM.

DIAGNOSTIC AIDS

It is very important that a thorough inspection of the wiring and connectors be performed. Failure to carefully and fully inspect wiring and connectors may result in misdiagnosis, causing part replacement with reappearance of the malfunction. See "Intermittents and Poor Connections" in DIAGRAMS.

If a serial data link malfunction occurs while the vehicle is running, FEDS will keep ECM fuel enabled to prevent a no-start condition on the next start attempt. The "SECURITY" and "SYS" indicators will flash to indicate a CCM problem has been noted and that the problem affects vehicle security. If the serial data link malfunction occurs with the vehicle at rest and the engine not running, FEDS will not enable fuel.

If the vehicle exhibits a cranks but won't run condition, the FEDS exchange has not been successfully completed. If the vehicle will not crank, the CCM is not satisfied with the PASS-Key(R) and is not allowing cranking, or there is a problem in the cranking system itself.