'96 Can't make up it's mind weather to downshift or not...Help!

[SoCalPhil]

Hey there...I have a 96 XLT V8 and we are having an issue with downshifting. Whenever you're going up a hill (even totally minor, small ones) the truck keeps wanting to downshift, then goes back into gear, then a minute later downshifts again.

The best way I can describe it is that the Ex can't make up it's mind what it wants to do. The tranny itself is fine, there are no problems shifting...no slipping, nothing. Just did a change of the tranny fluids and filter thinking that might be causing it, but to no avail.

Anyone have thoughts as to what is going on? Thanks!

~Phil

 

[FlyingBurrito]

Having the same issue. Looking into the VSS atm.

 

[FlyingBurrito]

Check engine light is on. Speedometer will read, but just barely and will only read when I reach higher speeds. It then shakes erratically and is several MPH off. Never cared because I use my GPS. Transmission shifts hard out of first and then can't seem to make it's mind up between first and second. When I get above around 40 MPH it's fine. Cruise control also started behaving strangely at the same time the odd shifting behavior began.

 

[OneLever]

I believe the vehicle speed sensor is used for both the speedometer and for the PCM to determine shift timing. Someone with more knowledge than me in this will chime in.

 

[SoCalPhil]

Well, I don't have any of the issues that Burrito is having...Mine doesn't have any shifting issues, it just goes between in-gear and downshifting.

 

[my98nnj]

VSS and TPS both must be operating correctly in order for the trans to know how fast the truck is going and the load upon the engine.