Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
1987 Chevrolet Chevette L4-98 1.6LFACTORY OEM SERVICE PROCEDURE
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.
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.
Factory Service Tools
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.