How many miles is too many on 84 4 speed transmission (Page 2/2) 1985 Fiero GT APR 13, 06:03 AM quote Originally posted by jelly2m8: Computer don't care if you have a 4 spd or a 5 spd. throw that shift light bulb in the garbage, even Gm got rid of it. Fiero manual ECM's DO NOT have any gear position input to them. They don't have any input like that but they do know what gear you are in, with pre programmed gear ratios for the specific transmission, it compares the rpm to the speed, to know the gear, which is why it will never light in top gear. I don't use it, but it is a cool feature. I don't know which part of the ECM had that programming, but there is something that does care whether it is a 4 or 5 speed, or an 84 4:10, or an 84 economy.