Engine Control Module: Service and Repair

PCM Location.:

When replacing a production PCM with a service PCM, transfer the broadcast code and production number from the production unit to the service unit. The MEMCAL/PROM must be removed from the PCM being replaced and transferred to the new unit.

REMOVE
1. Disconnect battery ground cable.
2. Right hand kick panel.
3. Disconnect computer electrical connectors.
4. Remove computer mounting hardware.
5. Remove computer from passenger compartment.

INSTALL
1. Reverse procedure to install.
2. Perform FUNCTIONAL CHECK to verify proper installation.

Data Link Connector (DLC) - Located Underdash:

FUNCTIONAL CHECK
1. Turn ignition "ON."
2. Enter DIAGNOSTIC MODE by jumpering the Data Link Connector (DLC) terminals "A" to "B" with key "ON" engine "OFF." A code 12 should flash four times if no other codes are present. This indicates the MEM-CAL/PROM is installed correctly and the PCM is functioning.
3. If codes 19, 42, 43 or 51 occur, or if the "SERVICE ENGINE SOON" light is on consistently with no codes, the MEM-CAL/PROM is not seated properly or is defective. If not fully seated, press firmly on the ends of the MEM-CAL/PROM.
4. Before starting engine reset Idle Air Control valve pintle position:
A. Turn ignition switch to the "ON" position.
B. Ground diagnostic "test" terminal for five seconds.
C. Remove ground.
D. Turn ignition "OFF" for ten seconds.
E. Start engine and check for proper idle operation.
NOTE
Disconnecting PCM from it's power source will clear all PCM memories. Since some operations (particularly IAC valve idle control) are "learned", it may be necessary to partially depress the accelerator pedal when restarting the engine after PCM memory is cleared. It may also be necessary to release the accelerator pedal very slowly when returning to idle, to prevent a stall. This will allow the PCM to "relearn" IAC valve position.
5. Learned operations may be restored by normal driving.