Engine Control Module: Service and Repair

Figure 1:

*** THIS PROCEDURE HAS BEEN UPDATED BY TSB # 88-42, dated 9/87

Some replacement ECM's may come with a replacement PROM already installed in them. If this situation occurs, remove prom from old ECM and install in rebuilt ECM.


When replacing a production ECM with a service ECM, transfer the broadcast code and production number from the production unit to the service unit. Also, during replacement, the PROM, and if equipped, the CALPAK must be removed from the ECM being replaced and transferred to the new unit. Refer to "PROM, REPLACE" and "CALPAK, REPLACE" for procedure.

1. Disconnect battery ground cable.
2. Locate ECM on passenger side under the instrument panel hush panel. (see figure 1.).
3. Remove ECM mounting hardware.
4. Remove ECM from passenger compartment.
5. Reverse procedure to install.