Archived transmission problems

[Miller]

hi all,new member with a 1-98 production 24valve auto trans that is starting to give me headaches. when on the highway in cruise the tach goes up in rpms,but the speed stays the same. have been told by a dealer that the clutch packs,coverter are shot. don't want to spend $3000. 00 if i don't have to. thanks for any advice.

 

[Joe G.]

Need a little more info on exactly what it is doing. If you are at a set speed, say 70 MPH, when the RPM goes up does it always go to the same speed? Or does it vary like something is slipping?



If it jumps up to the same RPM it may be a TPS problem so that the TCC unlocks. If the RPM is all over the place then you may have some stuff worn out like the dealer says.

 

[Missouri Mule]

Does the engine sound like it is running higher in rpms?

If not you mite being have tach problems at dash.



I agree with Joe about coming out of TC but it mite being shifting out of overdrive.



Which still could be apps(tps) or crank speed sensor.



Also does it absolutely only do it cruise?

Could have something to do with vehicle speed sensor but that mite cause speed variation.



If it does only in cruise than it has to be something related with cruise control.

 

[Joe Mc]

Sorry got a bit long.

Miller,



As the others have indicated it could be a few different things. On mine the cruise servo was going bad and caused fluctuations in rpm. Then almost a year after replacing the servo something similar would happen only the rpm would go up & down while at a constant speed. This time the TC lockup was hunting in and out causing the rpms to fluctuate 2 - 300 rpms.



Try this first - it's free and easy. Rarely do we get to use those two words together in the same sentence when referring to fixing something on our trucks. Disconnect the batteries (pos & neg on both batteries) for about an hour or longer if possible (I did it between arriving to work and lunch). Reconnect them, turn the ignition key to the "on" position (do not start) as if you were waiting to start, after all the bells and whistles stop - "slowly" depress the go pedal all the way to the floor and "slowly" release all the way out. The key here is "slowly", take about 10 seconds to go down & same to return up. Turn the key off and then start as normal.



The procedure outlined above reprograms the APPS (Accelerator Pedal Position Sensor) which tells all the computers what to do based on the various pedal positions. When the APPS isn't functioning properly things can become confusing for the computers - such as "should I lock the TC or unlock it?"



This worked for me for a few months then it started to happen again. I then purchased a noise filter from Diesel Performance Products for like $35 to cut back on electrical interference with the APPS. The wiring for the APPS is routed with a bunch of other wires to and from the computers, alternator A/C clutch etc. , etc. and will pick up on the "electrical noise" associated with these systems, of course this worsens with the age of our vehicles.



You may likely hear comments (positive or negative) from others about this product - I am not promoting anything here just communicating what worked for me, which is one of the great things about this site . . . sharing of information.



Hope this helps - try the free and easy things first - like you did by checking here first, before paying god knows what to someone whom may not be familiar with the quirks of out trucks.



Best darn $35 I ever spent on my truck was the TDR membership.



Good luck - let us know what worked for you.



Joe Mc

PS - fill out your signature - it helps make it easier to help each other when we know what we're dealing with.

 

[Reb.B]

Call Dave Georand, he probably won't charge you and he'll tell you how to rewire your apps sensor. Fixes the problem, or you could buy DTT box (for $35) that has two cappacitors, that cost about a $1 a piece at Radio Shack