M1009 shifting rough, high RPM, doesn't want to go Into 3rd.

[hotcorner216]

I've only had this truck 2 weeks...Yes I've read the mounds of threads and posts on he th400 and adjusting the vaccum modulator and testing for leaks...so I pressure tested it and read 40 for a second or two then bounced down to 20 and then back up to 40, and kept doing this so I turned the screw a little to the left and now it's shifting smoother, but still way too high on the RPMs and it hasn't adjusted unlike the smooth and rough shifting. Prior to adjusting it did shift perfectly 3 times (3 times out of maybe 300 miles) ....didn't do anything diffrent...just came to a stop, accelerated and it would be fine for the next 3-4 stops and then back to rough shifting....it's very annoying and I'd like to know if there's something im doing wrong...should I just change the module and hoses?


Any help/advise would be greatly appreciated.

 

[Recovry4x4]

Start checking for vacuum leaks. From there need to check vacuum source. If you are sure how to do these' the tests are well explained in the TM.

 

[ODFever]

Replace all of your vacuum lines. If that doesn't help, temporarily bypass the vacuum modulator. If you still have problems after bypassing the vacuum modulator, replace the transmission vacuum modulator.

 

[MarcusOReallyus]

Replace all of your vacuum lines.

Yep. Cheap. Easy. Should be done on these old beasts just as a PM. Good place to start.

 

[the skull]

Four inches of vacuum line fixed my weird high rpm shift problem.

 

[ODFever]

Glad it was an easy and cheap fix.

 

[Warthog]

Wow, the simple things.

It is said about CUCVs, "If it is electrical, clean it. If it is rubber, replace it."