Transmission Problems On A 1992 Expo. Options

[Jason_In_CO]

Hello, I've been reading through many old posts, and there is a lot of great information here, but unfortunately have not found a solution to my problem.

Summary:

1992 Mits. Expo
2.4 L automatic transmission.
174,000 miles.

I was driving about 50MPH when all of the sudden the vehicle acted as if it went into neutral. There was no clunks or other strange noises, and the transmission had not been having problems previous to this. I coasted to a stop, and tried cycling the shift lever through all of the gears including reverse, with the same outcome. The engine starts and runs fine, but I have no gears at all.

I towed the vehicle home and have tried the following with no success.

1. Checked the fluid level.
2. Dropped the pan and replaced the filter.
3. Checked the problem codes using a voltmeter. Am getting a 32 which is faulty MAP sensor. I thought it probably had nothing to do with the transmission, but decided to replace it anyway. When I went to the parts store, their computer says that there is no MAP sensor on a 1992 Expo?
4. I aslso found some information about reading the trouble codes for the transmission by placing the voltmeter across pins 12 and 6. I am getting a constant readout of quick pulses which indicates no code present.
5. Removed valve body and cleaned and verified operation of all the spring actuators.
6. Checked fuse for Transmission Control Unit.

I did read somewhere that the inhibitor switch can cause this, but don't know how reliable this is, and how to test it.

I am pretty much out of ideas, if you have any please respond.

Thanks,

Jason

[KiT TeUnG 2549]

The most likely cause would be yur TQ converter . The pump would not cause this type of situation but when the inner splines in the TQ converter wear down , this is the cause.

[Jason_In_CO]

The most likely cause would be yur TQ converter . The pump would not cause this type of situation but when the inner splines in the TQ converter wear down , this is the cause.

Thanks for the response. If the splines in the torque converter were worn to the point of failure wouldn't there have been symptoms prior to failure such as slipping in all gears?

I pulled the cooling line off and started the car just to see if the pump was pumping fluid. When the vehicle was in the park gear, there was no flow, but when I put it in drive, fluid started flowing. Is this normal? I though the pump pumped fluid as soon as the car started as it is connected to the crank shaft via the torque converter. Also, this is a F4A23 transmission. Are there any sensors or the TCU that could cause a problem like this?

[KiT TeUnG 2549]

The TQ converter is wut drives the transmission fluid pump. The splines just go. 98 percent the time they do not give any warning. It will not slip in any gear because there is no reason too. Thats the reason there was no fluid flow when yu pulled the line off. It wont slip in gears because there is no failure with the gears. Replace the TQ converter and yull be ok.

[Jason_In_CO]

The TQ converter is wut drives the transmission fluid pump. The splines just go. 98 percent the time they do not give any warning. It will not slip in any gear because there is no reason too. Thats the reason there was no fluid flow when yu pulled the line off. It wont slip in gears because there is no failure with the gears. Replace the TQ converter and yull be ok.

There is flow from the hose when I pulled if off, but only after I put it in drive.

[KiT TeUnG 2549]

GThe TQ is constantly driving the pump , there should be flow all the time. Im sure the flow was not much when yu put it in drive. Wut happened was that when yu put it ind rive it slightly altered the position of the shaft and the splines slightly grabbed. The TQ converter also drives the input shaft that the gears are on. Splines wear out. Its a thing that happends.