96 Windstar transmission

Driving home last night my transmission started acting strange. I was driving approximatley 90km/hr with rpms around 1800 (which I find is normal) when suddenly my rpms shot way up. I pulled over to make sure I could still physically change gears (P,N,D,2,1) which were all fine. I started driving again only to find that the rpms were not shifting as I accelerated, they simply kept going higher. My husband took the van for a short drive this morning only to have it operate perfectly fine.

Any ideas on what happened or is happening? What should we check first?

Driving home last night my transmission started acting strange. I was driving approximatley 90km/hr with rpms around 1800 (which I find is normal) when suddenly my rpms shot way up. I pulled over to make sure I could still physically change gears (P,N,D,2,1) which were all fine. I started driving again only to find that the rpms were not shifting as I accelerated, they simply kept going higher. My husband took the van for a short drive this morning only to have it operate perfectly fine.

Any ideas on what happened or is happening? What should we check first?
the number one cause of trans failure is improper fluid level, followed by poor maintance. I would start by checking the fluid level, which has to be done after the vehicle is at operating temp, as far as maintance goes it should be flushed about every 30k miles

From what you describe.....it sounds like the transmission is not shifting into the gears that it should.
If the little "O/D" light on the shift lever blinking?
If so, it is indicating that there has been a problem sensed with the transmission....and you can have those codes read at the dealer or other repair facility (that you trust).

The transmission has a "limp" mode....in which it will not shift any higher than 2nd gear. You have 4 forward speeds. I had that happen to my transmission.....and had high RPMs (which is caused by the transmission not shifting into 3rd or 4th gear).

One item that is a common failure is the Transmission Range Sensor (TRS).
The TRS sits on TOP of the transmission, and is not an expensive repair.
The TRS is connected to the cable that comes from the gear selector lever.....and tells the transmission electronics what gear you have selected.

If the problem is something inside the transmission.....then it is expensive.
I have the TRS in one of my pictures at http://community.webshots.com/album/201931518cScpNK

Having checked the fluid level while at operating temperature, idling in park, I found it was down below the crosshair section. We have since added transmission fluid and brought this back up to the correct level. Is there anything else we should look at or is this now a "drive it and see" situation?

The O/D light was not blinking at any time, nor was there any type of sign or warning that a problem was about to occur.

If this happens again, is there any way to tell if the transmission sensor is "dead" or should we just go ahead and replace it?

P.S. The vehicle has worked perfectly fine since the morning after the original problem occured.

Thanks!

Agree with WISWIND that an intermittent Range-sensor can cause those symptoms. When mine failed, the van would shift into second while driving at highway speeds. The part is around $25 and is easy to replace for a DIYer.