PLEASE HELP tranny will not shift on its own and no OD

[International-Harvester91]

My tranny for my 7.3 idi will not shift on its own and over drive will not kick in, the OD light flashes sometimes and my speedo is very loose or wobly. When i shift the truck manually it shifts smooth and the fluid is fine.


i would like to get this fixed before this weekend, because i have a boat i need to tow.


Thanks

[International-Harvester91]

anything? i mean i have searched it to death but i cant come up with anything, i could really use some advice on this, maybe speed sensors?

[dbkerley]

I'm sure someone that can help will come along soon. I'm not sure if this applies to yours - could it be the modulator or the vacuum line going to it.

I have a similar problem with mine and it just refuses to shift unless I depress the clutch first. I just don't know about these trucks sometimes. They can be really stubborn.

[International-Harvester91]

yeah thanks for the advice, allthough i dont have a clutch because i have an auto :]

[dbkerley]

Modulator and lines are an automatic. I have the A40D (?) in one of my vans and it has problems with the converter lock up solenoid. Factory defect because the exhaust is routed to close to it and as it ages it becomes heat sensitive. I also have had modulator problems (in other vehicles) that acted very similar to what you describe.

The bit about the clutch was just an attempt at some humor.

[International-Harvester91]

oh haha ok thanks ill look into that

[bdsmech]

is you tach acting up? i had same problem and changed tach sensor seemed to solve problem. you should scan for codes though o/d light flashing is telling you something. also lots of corrosion gets built up in connection on trans behind protector plate. clean it well could be bad connection..