What causes GM code 85?

Loose or corroded PROM or MEMCAL in the ECM Wrong PROM for the vehicle Failed PROM chip Poor ECM connector contact

How do I fix GM code 85?

Read codes with a paperclip jumper Remove ECM power, reseat the PROM or MEMCAL carefully Inspect PROM pins and socket for corrosion Verify the PROM matches the vehicle calibration Replace with the correct PROM if the error persists Do not drive far with this code since fueling may be wrong

85 PROM Error

Q: What does GM code 85 mean?

GM code 85 — PROM Error. Applies to 1988-1995 C/K trucks, Camaro, Corvette, Caprice.

Make: GM (1982-1995)
Category: Powertrain - Computer and Auxiliary Controls
Severity: Check Engine Light
Applies to: 1988-1995 C/K trucks, Camaro, Corvette, Caprice

How to read it

Code 85 reads as 8 flashes, pause, 5 flashes on the check-engine light. Jump terminals A and B on the ALDL connector with the key off, then turn the key on with the engine off and count the check-engine flashes.

What does GM code 85 mean?

85 — PROM Error. This code sets when your vehicle computer detects prom error.

Common causes of 85

Loose or corroded PROM or MEMCAL in the ECM
Wrong PROM for the vehicle
Failed PROM chip
Poor ECM connector contact

How to fix 85

Read codes with a paperclip jumper
Remove ECM power, reseat the PROM or MEMCAL carefully
Inspect PROM pins and socket for corrosion
Verify the PROM matches the vehicle calibration
Replace with the correct PROM if the error persists
Do not drive far with this code since fueling may be wrong