Transmission

[melissayoung]

Hey guys, I'm new to the board. My husband Alan and I just recently saved a VX from the junk yard. Alan had always wanted one. Anway found one in VA that had been in a flood and wouldn't start, bought it and replaced the main computer and all modules in the interior of the car. Started right up drove around the block everything was great. Next day, we go out to drive it, drives great for a couple of blocks then acts like its not in gear or is slipping, turn the engine off and restart it drives fine for a little ways, until you touch the brake or slow down then it does the same thing. We have changed the fluid so I know its not low. We are stumped as to what it could be. Alan is usually pretty good with cars, but he has never dealt with a transmission setup like this one. He says the transmission is solid shifting when it works, unfortunately when it works is sporadic at best. PLEASE HELP

[Anita]

It's possible that it might be an electrical problem with the tranny shifting. Dont know all the possibilities but the Mode switch does have something to do with gear to gear shifting. Any other ideas out there?

[t2p]

Ditto on/with the advice from Anita - I would check the electrical
connections and components first - that is provided all fluids were replaced, etc.
.
I had an 89 Pathfinder that had similar symptom(s) .......... it initially appeared the transmission was done ......... I was able to get it to a dealer ......... they were stumped ......... a quick check of the electrics showed no problems ....... so a few mechanics were convinced the trans was the problem ......... but the problem did turn out to be electrical in nature ..... some sort of connection or relay .........
.
there may be a few VX owners on this board than can help - many are not afraid of water crossings ..........
.
good luck ......

[VXMAN]

Did you replace the TOD (Torque-on-Demand) computer system, under the passenger seat? If not, I'd start there. Also, your 4L30E transmission is also computer driven, but I'm not sure where the computer is.

Dave...

[SGT.BATGUANO]

#1. Did he check the trans fluid level with the engine warm and running in park?

[melissayoung]

Thanks everybody for your help, we appreciate your prompt replies. Our VX is still having problems. Alan's replaced the TOD module under the passenger seat with one out of a salvaged vehicle. He also has changed the transmission fluid and checked it with the vehicle running and in park, also ran through all the gears. He also replaced the fluid in the transfer case and filled it to the filler hole, however the TOD light on the dashboard does not illuminate AT ALL like we read it was supposed to. I wonder if its possible the module that we have does not work or if it is the mode switch possibly. He has checked all connections that he could find and cleaned and replaced as needed. Vehicle still doing the same as before.

[nater]

List of some likely possibilities (besides disastrous mechanical failure).

1. Bad fluid. Pump out ALL of the trans fluid professionally. Try http://www.aamco.com See my other post in another thread.

2. Neutral-Start safety switch. It's mounted to side of the transmission. It tells the trans computer which gear is selected. If replacing, be sure to adjust it properly upon installation. (It's a slotted mount like a distributor). You'll need an ohmmeter and a service manual to do this.

3. Trans computer. (Is it seperate from engine? I do not know).

3. Solenoids in the valve body. These are probably okay, if not, they will probably recover if you change out all of the trans fluid. They could be corroded, though.

4. Torque converter. If there is water in the fluid, it can slip. It could also be damaged inside, causing slippage, but this isn't usually intermittent.

5. Bad stator. This is the thing that lets the trans slip while coasting (and grab under power, like a ratchet). If it has come only a little loose at its attachment point, it could work fine while cold or under light load but break free when power is applied or some heat builds up. This is internal to the transmission. You'd probably find little pieces of metal on the drain plug if this were the case.


Finally, what gear does it slip in? It makes a big difference whether it's all gears, or a particular gear.

Nate

[nater]

A few more things: To diagnose if the problem is transmission or transfer/TOD related, next time it happens, shift to 4L and drive around a little. In 4L, TOD is bypassed, it's just a straight mechanical connection, and power is split halfway between front and rear.

Also, the transmission should work okay without any electronics. It will feel sluggish during shifting, and will not choose optimum shift points, and the torque converter will never go into lockup mode, and the overdrive likely will not work either. You can disconnect all the connectors to the transmission (NOT the TOD) and drive it around, and see if the problem goes away.

This won't hurt the transmission, it will simply run in "default" mode. It will feel a little funny, but it should be solid, that is, it shouldn't slip and should shift reasonably well through third gear.

A little insight: At the core of all transmission problems are three possibilities:

1. Broken/ damaged/ severely worn internal moving parts.
2. obstructed or diverted pressures inside the hydraulic "circuitry" called the valve body. These circuits change pressures based upon different factors, wheel speed, gas pedal "kickdown" cable, engine speed, and current gear.
3. Bad electronics or electrical connections. These electronics only coax some of the circuits in the valve body through the use of solenoids.

You should invest in the factory service manual.

http://www.helminc.com

Nate

[Zu4two]

My two cents....

Shift into 4 low and see if the front wheel indicators in the TOD icon light up.

Did you change the powertrain control module? It's the box located at the bottom of the center console, in front of the gear selector, under the rounded black cover.

Try operation in the individual gear selections (1,2,3,D,R). Does the problem occur in all gears?

There are about a dozen connectors associated with the TOD circuits, located all over the truck. Any one of them could be a problem.

Download the repair CD off of Tone's site, www.tonemonday.com. It's under the VehiCROSS section and it's FREE.