My 4x4 1993 F250 overdrive light flashes when I let off the accelerator pedal and stops flashing when I accelerate. I believe it is an AOD. Any ideas anyone? Thanks.

 

The F250 and F350 never came with an AOD from the factory. Yours is an E4OD.

Your best bet is to check for codes: Fuel Injection Technical Library » How To Run a Self-Test

Or purchase one of these to display codes: Equus 3145

 

Thank you. I had a strong suspicion that it was an E40D.

I did take the pickup down to the local parts store and had them run their diagnostic scanner which couldn't seem to pull anything from the port.

 

is your tach going dead at idle?

 

Clean the pins in the connector. Use some contact cleaner. Sometimes you have to get a little more aggressive, I use a small screwdriver from time to time.

 

You know, I think the tach is going dead at idle. I'll check again tomorrow.

 

The tach does go dead at idle.

I don't know if it is related but when I step down hard on the accelerator pedal to pass or climb a hill while O/D is on, the transmission downshifts too low and tachs-out without upshifting. It will only upshift if I turn off the O/D.