Electronic Calibration Unit (PROM) Replacement Service Number:1226551

THE IGNITION SHOULD ALWAYS BE OFF WHEN INSTALLING OR REMOVING THE ECM CONNECTORS

Figure 1:

Figure 2:

Remove or Disconnect (Figures 1 and 2)
1. Connectors from ECM
2. ECM mounting hardware

Important

Figure 1:

ELECTRONIC CONTROL MODULE (ECM) MOUNTING HARDWARE NOT ILLUSTRATED. HARDWARE CONFIGURATION WILL VARY WITH CAR DIVISION.
3. ECM from passenger compartment
4. PROM access cover

Figure 2:

5. PROM removal

Figure 2:

Using the PROM extraction/insertion tool (Figure 2), start at the opposite end from the reference mark and gently work the extraction tool tang under the PROM with a slight side-to-side rocking motion.
Important
DO NOT ATTEMPT TO LIFT THE MODULE OUT AT THIS POINT! Go to the reference end of the PROM. Push the extraction tang firmly under the PROM, with the thumb pressing on the tool as close to the tang end as possible. Make sure the tang is completely under the PROM, but above the mating socket. Grasp the PROM firmly between thumb and forefinger while pulling upward, removing the PROM from the mating socket.
Remove or Disconnect
1. New module out of its packaging
Important
Check the part number making sure it is the same as the one removed.

Figure 3:

Assemble (Figure 3)
1. PROM insertion tool to PROM.

Place PROM with the leads pointing downward on a flat surface. Press insertion tool down firmly over the PROM, making sure the reference end can be seen at the tool cut out end.

Assemble
Important (Before installing new PROM)
ANY TIME THE PROM IS INSTALLED BACKWARDS AND THE IGNITION SWITCH TURNED ON, THE PROM IS DESTROYED.

Figure 4:

1. PROM in PROM socket (Figures 4 and 5) Mate the PROM held by the insertion tool to the PROM socket on the circuit board. Make sure reference ends of both PROM and socket are aligned in the same direction.
Important
THE MODULE WILL NOT BE FULLY SEATED AT THIS POINT.
Turn the insertion tool over and using the blunt end press the PROM down until fully seated.

Figure 5:

Inspect (Figure 5)
For bent pins, properly seated in socket or installed with PROM and socket ends aligned.
2. Access cover on ECM
3. ECM in passenger compartment
4. Connectors to ECM
Measure or Check
1. Ignition on
2. Diagnostics
A. Code 12 should flash four times, (No other codes present.) This indicates the PROM is installed properly.
B. If trouble code 51 occurs or if the check engine light is on constantly with no codes, the PROM is not fully seated, installed backwards, has bent pins, or is defective, ^ If not fully seated, press firmly on PROM
^ If it is necessary to remove the PROM, follow instructions.
^ If installed backwards, REPLACE THE PROM.
^ If pins bend, remove PROM, straighten pins, and reinstall. If bent pins break or crack during straightening, discard PROM and replace it.
Important (Before installing new PROM)
ANY TIME THE PROM IS INSTALLED BACKWARDS AND THE IGNITION SWITCH TURNED ON, THE PROM IS DESTROYED.