Operation CHARM: Car repair manuals for everyone.
Manuals through 2025 now available!

Our trusted friends have launched a new website named LEMON, which has newer manuals. It also contains all the CHARM manuals.

LEMON is the logical successor to CHARM, I recommend you try it!

Link: lemon-manuals.la

Engine Controls - ECM May Contain Wrong PROM

87chevy26
Number: 88-42

Section: 6E

Date: Sept., 1987
Subject: SERVICE REPLACEMENT ELECTRONIC MODULES (ECM) WITH PROM INSTALLED


Model and Year: 1981-88 ALL MODELS
TO: ALL CHEVROLET DEALERS


It has been brought to our attention that some service replacement electronic control modules (ECM's) have contained a PROM. A PROM should not have been included in a replacement ECM as it may not be the correct PROM for the vehicle.

When this situation is encountered, the PROM should be removed from the replacement ECM and the PROM from the vehicle should be installed.