Overdrive not shifting correctly - Toyota Nation Forum : Toyota Car and Truck Forums

mhendley · 09-15-2003, 12:06 PM

I just picked this 91 4runner up and drove it halfway across the country. Only occasionally will it shift into overdrive. Checking the transmission fluid it appears to be fine but it also appears that someone has overfilled it. Could this be causing my problem ? What type of overdrive sensor does it have ? Vacuum ? Mechanical ? Electric sensor ? Other ? Thanks for any help.

dads4wd · 11-17-2003, 01:33 PM

I was wondering if you resolved your transmission problem. Recently, I inherited my father's 1989 4Runner. I took it on a trip this week and the same thing happenned to me. I'd be going along the interstate and the overdrive would drop out. I'd go from 2500 rpm's to 3500 rpm's. After finding the transmission dip stick (which wasn't easy), it appeared that the fluid was overfilled. Interested in knowing if you discovered the cause and cure. Thanks.

mhendley · 11-17-2003, 02:36 PM

Yes I know what the problem is. It is temperature related. The previous owner had removed the thermostat. The computer will only let it shift to OD when the engine is at operating temperature. 190 degrees for a V6. Watch your temp guage and see if your shifting in and out of OD corresponds with shifts of the temperature. Also use the search function on this forum to get lots of good advice. Good luck.

dads4wd · 11-18-2003, 09:20 AM

Thanks for the reply. Interesting because it seemed to drop out while coasting downhill. It would also shift back into overdrive after going up long hills. Very cold in NH which may add to the problem. Could it be as simple as blocking the airflow to the radiator with a piece of cardboard during the winter? I'll let you know. Thanks again for your help. I'm not exactly Mr. Mechanic!

MenaceSQL · 01-10-2004, 03:22 AM

My truck had the overdrive to 3rd gear and vice-versa shifting problem but it disappeared after a new motor got thrown in.

The same transmission with over 300,000 miles on it is still in use right now. One less problem for my truck though.

Fresco Bob · 01-14-2004, 07:38 PM

i know a chick with a '91, and she says hers hardly ever goes into OD, doesn't matter if its summer or winter, watever, any things that she might wanna check out?