My 1999 4X4 is allergic to snow! In the morning, after a blowing snow night, the transmission won't shift up. 15 miles or more in low, sometimes second, before it will find drive. Something gets wet! It only happens right around the freezing point. Maybe the Manual Lever Position Switch, or whatever it's called, on the side of the trans?
Also the throttle hangs up and it wants to race about 2000 RPM at the same temp. That could be ice in the throttle body. Shut it off for five minutes and it's OK, but it darn near put me into a snowplow yesterday when it wouldn't slow down.

 

74 people have read this post, but no reply? Does anyone have an idea what is going on with my transmission?

 

well you prolly got a couple of gremlins there.

1st... with the trans...it is a automatic ?? If yes... then 1st make sure that it has the proper level of fluid. Its possible that there is temp sensor on the tranny...it might be have bad connection or just faulty. Certainly couldn't hurt to spray down the linkages with lubricant/water protectant.

does it only do this in 4wheel drive?

2nd...with high engine idle you need to clean the IAC or just get a new one. then clean the MAF sensor ...make sure you clean the MAF sensor with cleaner that is safe for MAF sensors.

3rd... check for vacuum leaks

4th... check the throttle cable for frying...

 

1..4R70w trans, fresh fluid, does it in 2 and 4WD.
2..The racing engine bit happened at 50 mph, let off the gas and it kept going like on cruise control. Shut it off for 5 minutes and it idles right. Must be ice in the throttle body somewhere.
3...no leaks
4...cable is good, no binding.
I'll check the IAC next, I guess. I have another MLPS, I will try that too.

 

I have never had ice in a throttle body and my truck is a DD that lives outside in harsh Minnesota winters. A bad IAC will def. act up when it's cold....min e does, but it just refuses to idle until it warms up (the motor). The TPS is tied directly to the PCM and is a factor in how the tranny shifts. As mentioned....clean the MAF....which just means spraying it off with the correct cleaner. Pull the ductwork and get some throttle body cleaner...follow the directions on the can and clean up the butterfly real well. those things really get black and oily on higher mileage trucks. Get that area all cleaned up then proceed from there if needed with the IAC and TPS troubles.

 

Real cold weather doesn't do it. Just around the freezing point, and high humidity will do it every time. I have had it happen many times, everything from an S10 fourbanger to a Slant Six D100, and 351W 4v in a Mustang. Usually have to drive 30 miles or so at a constant speed before it builds up to the point that it won't just break loose when the throttle plates try to move. Just shut the engine off for a minute and it melts, away you go!

 

So once the throttle is not hung up, does it shift OK then?

 

No, the two problems seem to be independent of each other, The shifting thing seems to happen mainly after a night of blowing snow, so it makes me think something electrical is getting wet. As I said above, the manual lever position switch is my first guess.

 

What engine?

Check engine light on?

Overdrive light blinking?

 

The TPS is tied directly to the PCM and is a factor in how the tranny shifts.

 

It's a 4.6 engine.
The engine light came on yesterday first time, but everything was working great then! It was cold and dry, no malfunctions whatever.
The OD light doesn't blink, and OD works good if it shifts up at all. When it won't come out of First normally, I wind it up to 50 or so and it finds Second, then after 10 or 15 miles it will hit High and OD. Any other trans I would say the KD was sticking, but the 4R70w doesn't have a kickdown linkage.
Anyway it's working perfect now, been no blowing slushy snow for a few days.
Guess I'll wait for a warm day in the spring and sell it!

 

OK now with the Check Engine Light (CEL), go get the codes scanned again and see what has been tripped.

with this acting up only under blowing and sloppy conditions ( gotta think that same thing gonna happen in a heavy rain)... still think that it is a poor connection ......maybe a bad chassis ground.
A few WAG's, ran through my head as the transmission mount might be bad, the wet conditions offer just enough for it to twitch a bit...the other thing is that you have a weeping front window and the GEM module is being affected ( pretty doubtful on this because other electrical would be involved too)....or you steering column is a bit loose. Perhaps more reasonable thought is that the valve body is hanging up inside the tranny.

or As mentioned by others too...the Throttle Position Sensor (TPS) might be giving you fits....maybe a hair line crack allowing the moisture to penitrate only in extreme cold and wet conditions.

Like I mentioned these are WAGs getting the codes scanned again will show a direction
Selling the truck is a bit extreme....seems like it just needs some TLC

 

sorry double post

 

Man, don't sell it. That CEL is golden in a situation like this. It may not be related, but there is a good chance it is.

 

It's a 50 mile drive to a Ford shop, so I don't get it scanned very cheaply. I have another MLPS to try, but it's a bit ugly to climb under the truck these days. As long as it works good most days, I won't worry about it.
BTW, I just put the trans in it a month ago. The original one blew the forward clutch housing. I changed the filter and lube, and checked what I could inside, everything looked like new. Somewhat surprised to see there is no way to adjust the bands..........