91 f250 trans issues
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4th Gear
Joined: Jul 2022
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91 f250 trans issues
91 f250 wont shift unless i rev it
it has the c6....i dont know anything about these transmissions please any help would be apreciated.....when i move the gear lever it does nothing until i bury the throttle at which point it spins tires...and every time i stop or change into a different gear (anything other than the gear i started in) i have to do it again, any help would be appreciated
it has the c6....i dont know anything about these transmissions please any help would be apreciated.....when i move the gear lever it does nothing until i bury the throttle at which point it spins tires...and every time i stop or change into a different gear (anything other than the gear i started in) i have to do it again, any help would be appreciated
Mountain Pass
Joined: Jan 2022
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I dont recall if this model year is efi, if it is it could be a lot of different things. But since you can get it to shift only when throttle is floored to me sounds like your computer is not reading input right, like the tps not relaying info to the pcm. Or the pcm itself is at fault.
Cargo Master
Joined: Nov 2009
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The C6 is a completely mechanical transmission. There is no PCM. The computer doesn't figure into it, at all. Check the vacuum line to the modulator (on the rear passenger side of the transmission), And make sure the kickdown cable is connected and operates freely (It runs from the throttle body, down to a lever on the transmission)
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4th Gear
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The C6 is a completely mechanical transmission. There is no PCM. The computer doesn't figure into it, at all. Check the vacuum line to the modulator (on the rear passenger side of the transmission), And make sure the kickdown cable is connected and operates freely (It runs from the throttle body, down to a lever on the transmission)
Would the kickdown cable cause it not to shift without heavy throttle?
Cargo Master
Joined: Nov 2009
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The kickdown cable causes the transmission to downshift from 3rd to 2nd when you stand on the throttle (Possibly from 2nd to 1st as well, I don't remember). So it's not likely to be your problem. The Vacuum Modulator is the more likely culprit, it's either not getting vacuum, or the diaphragm in the modulator itself is ruptured.
Mountain Pass
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4th Gear
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Ok i will replace vaccum modulator tm evening and see if that helps it, should i still do a fluid and filter change, because i bought the truck with the issue and who knows how long he drove it like this
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Cargo Master
Joined: Nov 2009
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Who said replace the vacuum modulator? I said check to see if it's getting vacuum or not.
There is no "filter" in a C6. There is a screen bolted to the bottom of the valve body where other transmissions have a filter, you can clean that, but unless it's really messed up, there's no reason to replace it. But given as it's an automatic transmission, dropping the pan only changes a few quarts of the fluid.
To do a complete fluid change, the procedure is the same as the following: https://www.ford-trucks.com/articles...-transmission/ But you'll only need about 14 quarts.
There is no "filter" in a C6. There is a screen bolted to the bottom of the valve body where other transmissions have a filter, you can clean that, but unless it's really messed up, there's no reason to replace it. But given as it's an automatic transmission, dropping the pan only changes a few quarts of the fluid.
To do a complete fluid change, the procedure is the same as the following: https://www.ford-trucks.com/articles...-transmission/ But you'll only need about 14 quarts.
Frmr Ford Trans Engr
Joined: Aug 1999
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From: SE Florida
The kickdown cable causes the transmission to downshift from 3rd to 2nd when you stand on the throttle (Possibly from 2nd to 1st as well, I don't remember). So it's not likely to be your problem. The Vacuum Modulator is the more likely culprit, it's either not getting vacuum, or the diaphragm in the modulator itself is ruptured.
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