REMOVAL & INSTALLATION
See Figures 1, 2 and 3
As stated earlier, all computer control modules container information regarding the correct parameters for engine and system operation based on vehicle applications. In most modules, this information takes the form of a PROM chip or MEM-CAL, though some modules also store this information in an EEPROM. Some later model vehicles, also include a Knock Sensor (KS) module which is replaced like the PROM and MEM-CAL.
Replacement computers are normally not equipped with this PROM/MEM-CAL/KS module; you must transfer the chip from the old component. The EEPROM is a permanent memory that is physically soldered within the PCM. Unlike the PROM used in some earlier applications or the MEM-CAL, the EEPROM is not serviceable. If the PCM is replaced, the new PCM will have to programmed using a Tech 1®or equivalent scan tool.
- Make sure the ignition switch is OFF , then remove the computer control module from the vehicle.
- Remove the access panel. Note the position of the MEM-CAL/PROM/KS module for proper installation in the new ECM.
- Using 2 fingers, carefully push both retaining clips back away from the MEM-CAL/PROM/KS module. At the same time, grasp it at both ends and lift it up out of the socket. Do not remove the cover of the MEM-CAL/PROM/KS module.
- Fit the replacement MEM-CAL/PROM/KS module into the socket.
The small notches in the MEM-CAL/PROM/KS module must be aligned with the small notches in the socket. Press only on the ends of the MEM-CAL/PROM/KS module until the retaining clips snap into the ends of the MEM-CAL/PROM/KS module. Do not press on the middle of the MEM-CAL/PROM/KS module, only the ends.
- Install the access cover and retaining screws.
- Make sure the ignition switch is still OFF , then install the ECM, as outlined earlier in this section.
1988-94 Vehicles, Except 1994 3.4L Engine
- Turn the ignition switch ON .
Enter diagnostics, as outlined later in this section.
- Allow Code 12 to flash 4 times to verify no other codes are present. This indicates the PROM/MEM-CAL is installed properly and the ECM is functioning.
- If trouble Codes 42, 43 or 51 occur, or if the Service Engine Soon light is ON constantly with no codes, the Mem-Cal is not fully seated or is defective.
- If it is not fully seated, press firmly on the ends of the PROM/MEM-CAL.
- If installed backwards, replace the PROM/MEM-CAL.
Any time the PROM is installed backwards and the ignition switch is turned ON, the PROM is destroyed.
- If the pins are bent, remove the PROM/MEM-CAL, straighten the pins and reinstall the PROM/MEM-CAL. If the bent pins break or crack during straightening, discard the PROM/MEM-CAL and replace with a new PROM/MEM-CAL.
To prevent possible electrostatic discharge damage to the PROM or MEM-CAL, do not touch the component leads and do not remove the integrated circuit from the carrier.1994 3.4L Engine and All 1995-96 Vehicles
- Using a Tech 1®or equivalent scan tool, perform the on-board diagnostic system check.
- Start the engine and run for one minute.
- Scan for DTC's using the Tech 1®or equivalent scan tool, as outlined later in this section.
- If trouble codes P0325, P1361, P1350, or P1623 occurs, or if the MIL (Service Engine Soon) is ON constantly with no diagnostic trouble codes, the PROM or KS module is not fully seated or is defective.
- If it is not fully seated, press firmly on the ends of the PROM/KS module.