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overdrive turns off/tranny light comes on

03-15-2004, 02:40 PM
Help! while driving on the thruway going 60 MPH all of a sudden the overdrive is off, the RPMs rev and then the overdrive is back on. This occurs every so often.

While towing a 12 foot trailer loaded with plants, my tranny temperature light comes on with the warning sound and then it goes off after about 20 seconds. when I tow I turn off the overdrive. is this just a normal function of the engine or is something wrong? I know I need a tranny flush. I have 50k miles, V8 5.2L :banghead:

03-16-2004, 12:01 PM
the only time my tranny kicked out of over drive on the high way
was when it overheated. I can not remember the exact temp. but
after the trans temp reaches the max set point it kicks it out of
over drive. On my truck the damage was done and at 90000 miles
my tranny was lost. Hopefully you just have a bad sensor, either
way this could be a major problem waiting to drop on you. If your
still under warranty take it, if not start looking for a trusting trans
guy, cause mine set me back about 1600.00. Good luck!

03-16-2004, 03:52 PM
Get that checked, next thing you know you'll be putting a new transmission in there.

Some guys I know in town here cooked their auto tranny trying to pull a boat out of water. They put a standard tranny in right after that.

03-17-2004, 01:48 PM
That sounds like exactly what our truck is doing. It has 44,000 miles with the big v8 in it.

I heard two seperate fixes that I want to see if anyone has heard of.

The first is to remove a valve in the transmission that Dodge put in that doesn't work like it's supposed to and it ends up doing more harm than good.

The second is to remove some filter like thing between the tranny and the cooler that has a tendancy to clog and block off your coolent lines.

This was second hand information to me that came from two differant transmission shops here in town. My cousin has a 99 Dodge Ram that she just had to have the transmission rebuilt because of almost the same thing I think.

We havn't tried anything yet until we get a little more feedback first, but I would love to find out if anyone has atleast heard of either of these. Thanks.

03-19-2004, 12:28 AM
Need to monitor the transmission temp with a scanner. To see exactly what temp its downshifting/overheat light comes on. Could just be a problem with TOT(Transmission Oil Temp) sensor. If you are forcing a downshift, then the overheat light comes on, this is another problem. Couple of things to do.

There is a one-way check valve in the cooler line. You can take it out. But, if the rig sits for many days you could have delayed engagement cold , as the torque converter can drain its fluid into the pan. If this happens, you should splice in a one-way check valve for the Ford cooler lines.

You can try a big big aux cooler. Not the tube types. Get Hayden or Tru-Cool(the ones that look like a radiator). The biggest one possible to fit in front of radiator. Some times even bypass the radiator.

If you are forcing a downshift. Do the above and then a torque converter with 200 RPM less stall. As in force downshifts there is no lock-up converter operation so a lower stall helps.

03-22-2004, 01:59 PM
We just drilled out the check valve in our coolent lines over the weekend and our truck seems to be doing better. We haven't had the chance to load it up and drive it very far, but in the short distance that we drove, it did fine.

Rex, you said that we might get a delayed engagement, would letting the truck warm up fix that? We only drive the truck like once a month, so we really want to make sure that everything is perfect on it.


03-22-2004, 03:56 PM
You'll just have to wait and see if you have a drain back issue after it sits that long. Maybe with that low of miles it won't. I don't know what model year you have. If its pre-'97 then you should start it in nuetral to get lube oil moving quickly inside the transmission. If dipstick says "check in park" then no need for nuetral startup.

03-23-2004, 12:38 PM
Thanks for the help, your the first person that I've talked to that has heard of this check valve other than the transmission shop. It's a 99 1500 with the big v8. I'm not sure wich transmission it has in it though other than an auto. You mentioned something about replacing the valve with one off of a Ford. I take it those are designed differently and have a less chance of clogging?

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