Sidewinder

Does anyone know exactly what inputs the computer looks at to lockup the torque converter on a '95 47RH. Line pressure? TV setting? TPS voltage? Vehicle speed?...

With lots of advice from the members here I now have my tranny shifting almost perfectly (Adjusted throttle linkage, 3000 GSK, adjusted TV cable, opened and cleaned TPS, adjusted TPS voltage and bypassed temp sensor)

The only thing left is the TC lockup. The tranny shifts through the gears great but once it shifts to OD it then locks up about 3 seconds later. I would like it to delay the OD -> OD LOCK till the MPH gets a little higher.

I can change the shift points throught the gears with the TPS voltage but it still locks up too fast. It will also stay locked too long as the truck slows down and it starts "bucking".

I know I can install a forced LOCK/UNLOCK switch (which I will do anyway) but I would like my automatic to shift automatically if possible.

Any ideas?

mr T

hahaha i wanted this done a while back (postponing lockup to minimize the rpm drop) but there really isnt a solution in overdrive i dont think except and "unlock/lock switch"...in 3rd i can control the lockup with the overdrive button so i almost have zero rpm drop and the cleanest/smoothest lockup ever...but in over drive i dunno...that switch may be ur best bet...but if someone knows then i wanna know too!!

infidel

It sounds like you have it figured out except that the lock up mph in the PCM as measured by the VSS can be reflashed by the dealer to a higher mph. I had my RH reflashed under warranty when I complained, had it bumped from 47mph to 55 mph lockup, it now unlocks at about 50 before it didn't unlock till 40.

Dealer is the only one who can reflash them. You might also have trouble now finding a tech who knows how to do it since the DBR comp system used on pre-'96 has been out of much use now for almost ten years. Most dealers still have the readers but I've found most don't have any techs that know how to use them.

Sidewinder

Thanks Infidel!

You always seem to answer my tranny questions! I thought these trucks were too old to have "programable" computers. That sounds like exactly what I want to do! I think I will try some dealers around here to see if anyone can do that (from whatever it is now to 55 MPH). I like the idea that it will unlock sooner too!

So the thing I need to do this is called a DRB computer system?

Any one got any documentation that might have the procedure in it so I can "teach" the techs how to do this reflash for me.

EDIT: Is there a setting for lockup in OD and 3rd or will changing one setting change both. Right now the lockup in 3rd is OK.

mr T

hey ask them while ur searchign if there's any way at all i can lock up in 2nd (wirign up a switch or whatever) cause id like to drive in manual 2nd and locked in some places ...but i do have a completely stock tranny

Sidewinder

Reserecting this old thread. I can't stand this early shifting into OD - everything shaking at 45 MPH. Can anyone tell me what kind of signal is sent by the VSS to the PCM for the OD shift. If I know what it is (DC voltage, AC voltage, frequency...) maybe I can modify the signal to delay the shift with a resistor or op-amp or something. There must be some way to "fool" the computer into delaying the shift. The dealers around here do not want to help with my old '95 by reprogramming the computer. Either they don't want to or they don't know how - hard to tell.

I know I can wire up a switch but I would prefer the automatic tranny to be automatic.

Any ideas on the signal being sent to the PCM and also any wiring diagrams to tell me what wire is being used for the input on the computer.

Thanks!

jimk

Bill will have to give you the correct answer but I think that there are two different PCM one can be reflashed one cant. I dont have the part numbers handy. I talked to a fellow about the same thing too early lockup. He told me that he had used a relay ,with a time delay, to effect the lockup. I was not sure that was exactly what i wonted. Good luck Jim

LanceD

what changed when you bypassed your temp sensor? how did you do that?

Sidewinder

For me only one thing changed when I bypassed the sensor. The tranny would shift into OD and lockup right away when it was below freezing. Before I had to wait a few minutes for the temperature to come up for it to work. I just tried the bypass to make sure the sendor was not bad - and it wasn't.

The temp sensor will control the OD and lockup for the tranny when the temperature is too low or too high.

To bypass the sendor just unplug the connector at the sensor and put a 1000 Ohm resistor between the terminals. This fools the computer into thinking the tranny is always at operating temperature.

b.lee

Have you tried flooring it from a get go and see how / when it shifts / locks-up ?

Have you tried flooing it when it starts to 'buck' ?

rhino 660

the ATS trans command or whatever its called can controll lock up speed and a whole lot more but its like 400 bucks. im going to get one sooner or later so i can use my exhaust brake. read this to see all of its features
https://www.atsdiesel.com/PDF/120505...ge%2094-98.pdf

Teddy Bear

Why do you want the converter to lock up later? When the converter locks all the power is getting to the ground, provided that the converter isnt slipping.

rhino 660

to prevent the engine from lugging at 45mph