I have a 94 with a 6.5 turbo. I have noticed that lately while I am driving down the road and holding the accelerator at a constant speed, lets say 60 mph, the check engine light will come on. If I let off of the acc. it will go right back out. Speed back up and hold it steady, right back on. I haven't had the light come on before, and I was wondering if this was normal for these trucks.

Do you know what codes she is throwing? If you don't know how to check codes go to kennedydiesel.com and click on tech tips then on 6.2/6.5 tips, and some pictures will come up, just click on the one that says reading codes. After you get your codes, someone in here can definitly give you some good advice about what to do from there. Also, welcome to the diesel place! Hope you get as much help as I have.

Jump ALDL pin A to B with ign on to see codes flash on the check engine light. When finished, step down on the fuel pedal till code 12 flashes.