Engine/Transmission (1998.5 - 2002) transmission eratic shifting from 2nd to 3rd and 3rd to OD

[SMalafy]

I have a 2001 2500 which is giving me problems at speeds around 35 to 40 and 50 to 55 mph shifting.
I have rerouted my alternator wire around to the front of the radiator to the right side of the the battery when I done this that stopped it for a while. Then it started again so I changed the TPS and got a new one from Rock Auto (Walker Product) and reset the new 1 with the ignition on and the motor not running but am still having problems with the shifting at those speeds. A few years back I added a Rev Max towing valve body and a larger fluid pan adding 1 gal. more of fluid. I did not have problems with the shifting then but I am wondering about the fluid pan as they did not give me an extension tube for the deeper pan. Don't know what to think although it does seem like the TPS. Any one ever have a problem like this or know what it might be ?

 

[BigPapa]

Remove, clean, and inspect the speed sensor in the rear of the transmission on the driver side. The tip is magnetic and may be covered with shavings.

 

[SMalafy]

Remove, clean, and inspect the speed sensor in the rear of the transmission on the driver side. The tip is magnetic and may be covered with shavings.
View attachment 137238

Remove, clean, and inspect the speed sensor in the rear of the transmission on the driver side. The tip is magnetic and may be covered with shavings.
View attachment 137238

I am assuming I will have to drain the transmission at least part way if not all the fluid ?

 

[BigPapa]

No, shouldn't have to. I don't recall losing any fluid when I replaced mine.

 

[SMalafy]

No, shouldn't have to. I don't recall losing any fluid when I replaced mine.

OK then I'll take it out and see what it looks like . Thanks

 

[SMalafy]

No, shouldn't have to. I don't recall losing any fluid when I replaced mine.

Well the sensor was dirty and I did have about 4 oz or so of fluid pour out. The transmission shifts better but still between 45 to 50 mph it still gets erratic like it can't make up its mind

 

[BigPapa]

Well, it was worth a try. Didn't cost you anything. Hope you get it worked out.

 

[SMalafy]

Well, it was worth a try. Didn't cost you anything. Hope you get it worked out.

Yes it was worth it. As I said it did improve it somewhat. Might have to check the band adjustment. Thanks again

 

[Ozymandias]

Solenoid and especially pressure transducer still factory? They are cheap and easy to replace. Very important parts for the shift behavior.

Band adjustment should be done at every fluid change, means 30k.
But is only for shift quality and has nothing to do with shift timing.

 

[SMalafy]

Solenoid and especially pressure transducer still factory? They are cheap and easy to replace. Very important parts for the shift behavior.

Band adjustment should be done at every fluid change, means 30k.
But is only for shift quality and has nothing to do with shift timing.

Thanks for the info. I am pretty sure both of those were replaced with the upgraded towing valve body I had installed a few years back. Since I cleaned off the transmission speed sensor maybe I should try a reset on the TPS.

 

[Ozymandias]

They don't last very long, at least the pressure transducer I'd exchange just to see if it helps. It's very very cheap and very important at the same time.

 

[SMalafy]

They don't last very long, at least the pressure transducer I'd exchange just to see if it helps. It's very very cheap and very important at the same time.

I really do not use the truck that much and since the swap out with the valve body I might of put 6k or so on the truck. So you are saying the BD replacement does not last long ! They cost 80 dollars.

 

[Ozymandias]

Reviews aren't stellar, so I went a different route myself even with the BD Valvebody, which I like a lot.
But 6k is really not a lot of miles.

Problem is with the proper equipment you could see demand and actual line pressure, demand and actual set of TcL, 4th and OD.

Without diagnostic equipment we just throw parts at it, beginning with the cheapest ones first..

 

[Ozymandias]

Just basic Information.

Shift point 1-2, 2-3 are strictly set by line pressure, line pressure is set by the PCM through transducer and solenoid. If shift timing is not consistent you have to look at the line pressure.
3-4 shift is fully on the PCM, so is converter lockup.

PCM also takes throttle position into account to determine shifts with always same algorithm.
But shift pattern is so consistent that after some time we can shift the transmission by throttle input like a manual within certain limits.
If that pattern is off - the line pressure is wrong.

 

[SMalafy]

Well, it was worth a try. Didn't cost you anything. Hope you get it worked out.

Its been a while since you replied and I have not been on this site for a while too but I just wanted to let you know I put in a new sensor and all my problems went away