I just bought a 93 1 ton dually 4X4 with an automatic. The transmition is shifting very odd.

A little background. It has 400K miles so I know the tranny isnt original. The truck appears to be stock in every respect so I assume the tranny is also. I am currently taking care of a lot of little problems. On another post I found out the black box behind the glove box was for the antilock brakes. It had been disconnected. I reconnected it and the brake/abs light came on like the other post said. I went for a test drive after tightening up the steering and the transmition shifted very smoothly, just like the 1995 auto 2wd I own. This is not how it had been shifting. I stopped and ran it through the gears a half a dozen times, each time shifting smoothly.

Next I disconnected the ABS box again and ran through the gears again. This time it shifted like it has since I bought it. In order for it to shift to the next gear I have to almost hold it to the floor. It runs up very tight and when it shifts. . . .BAM!. .. The 3rd to 4th shift isnt so bad but unless I run the RPMs up it wont go to next gear.

Hooking the ABS back up made no change the next time, so it probably was just a coincidence. The reason I brought it up was it was the first time it has shifted like my 1995 and the way I figure it should.

Where do I start looking? What could cause it to run up so tight before shifting and then on one start-up it shifts through the gears half a dozen times beautifully? Sorry this is so long but this site is great for troubleshooting and I figured to give some background to start with.

Also, how do I tell if the TQ converter is locking without a tack? I cant seem to hear a change but this truck is a lot louder than my 95. Thanks guys in advance.

 

i had similar trouble with my 92 i went to http://www.piersdiesel.com/Tech1GTPS.htm
check it out that helped me good luck

 

I went to the piers site. It says adjusting the TPS will adjust the 3-4 shift. My 3-4 shift isnt too bad. Its the 1-2 and 2-3 that have to be almost against the governor before shifting. The piers page made one reference to the TV cable. Im going to do a search for that.

Does anyone know what else might control the RPMs for shifting or why trans shifted great one run and so harsh the next?

 

did you check the fluid level?
perhaps the bands need adjustment...

your torque converter will never lock so dont worry...

 

Fluid level is good when warm. Havent adjusted bands yet. Fluid looked and smelled good so figured that could wate. Tranny shifted good one run and then not the next, thats whats especially confused me.

What about the TQ. I thought I had read somewhere that the 93 was a lock up TQ. What does it have the TPS and ECM for ?

 

the overdrive.

 

I must have been thinking of something I read on my 95 as far the TQ. That still leaves my problem of the high shift points. What controls the shift point from 1-2 and 2-3? and why it shifted smooth a number of times on one run and then after shutting the truck off, the next time it has to go to the governor.

 

hydraulics, might want to drop the pan and see if theres a pile of shavings or something plugging the filter in there...
perhaps someone more knowledgable will chime in...

 

The TV cable which comes from the throttle linkage to the transmission, if mis-adjusted will affect the 1-2 and 2-3 shifts. I don't remember the spec right off, but you want about .125" gap between the cable and the rod at the throttle linkage with the linkage in the idle position. This also could be a problem of STUCK OPEN TV cable. Perhaps the cable is corroded and bound and the throttle valve is stuck wide open at the transmission.

 

I actually needed to have a return spring placed on my throttle cable to pull back the TV cable so it would return back to the original spot. Otherwise, it was getting the wrong setting and causing it to shift strange.

The TV cable controls the pressure it takes to shift the first 3 gears, I believe. The TPS controls the 3rd - 4th shift.

 

I put a spring on mine as well sorry i didnt mension it before 1st thing i did that sliding plastic thing close to throttlr wasnt sliding to good i sprayed about 1/2 a can af wd40 then a spray some from time to time took a week and i noticed some difference

 

Im busy tomorrow, but first thing next week Im going to get under there while my wife moves the throttle and see what is happening at the transmition with the TV cable.
Does anyone know what the spec. for the TV cable adjustment is? What does adjusting one way or the other do for shift points? Im guessing if this is it, its something sticking since it shifted great one run and not the next.

 

The throttle valve cable is the place to start here......
Very minor tweaks are the way to go.
If you move the TVC back a tad you'll find your shifts points will change. Backward (toward the firewall) is the first step...then drive it and see how it has changed.

You are correct regarding the TPS...it is responsible for the 3-4, 4-3 shift and, not the other shift points.
If you really need to tweak the shift RPM up or down there is an adjustment inside the trans for that.
I'll post a link to see the VB and the adjustment you need to use for this. One full turn of this increases or decreases the RPM shift point by roughly 75 RPM.

pb..

http://www.turbodieselregister.com/u...um&albumid=489

 

Hey Bushy, tried the link and it wouldn't go anywhere. Says I have to be a registered user to use.
Two other questions: If the adjustment in the transmition adjusts the RPM for shift points, what is the TV cable adjusting?

Other question, looked at your truck pics and like the winch bumper/grill guard you have. Did you make it yourself or buy off the shelf and if so, where?

THanks