parked on a honda

First off, before ya'll start tellin me that my question is answered somewhere else on here, i'll bet you its not. Ive searched not only this site but many others for a solution to my problem, with no luck.

Basically its in the title. my 1990 4runner 3.slow automatic wont stay in overdrive. I noticed the problem a couple weeks ago when i was driving down the freeway at about 70, and all the sudden my rpms shot up to around 3500, and i noticed that the O/D switch on the shifter didnt do anything but make the light turn on or off on the dash. Heres the thing though. If the O/D button in set to on, i can be driving down the road goin say 50 and when i let off the gas, it WILL shift into O/D, but the second i put my foot on the gas to accelerate or even to maintain that speed, it pops back up into 3rd. Also, everyone else who has had this problem had noted the O/D light flash on and off. mine does not do that, which is one thing unique to my issue. not sure what that means.

I had found people with what seemed to be the same problem, but i tried their solutions, and still the problem persists!! I replaced the O/D solenoid like i had been reading about (whoever put that gasket on the tranny pan did a hell of a job, so damn tight lol), and that didnt fix the problem.

I'm a poor college kid who couldnt afford to keep throwing parts at my truck, so I took it in to Gregs Japanese Auto, and $400 later they told me "yeah we threw in a new throttle positioning sensor and its running great!". picked it up the next day, and still the problem is there as prominent as ever. (makes me wonder if the assholes even test-drove it)

So now, im about $550 into this problem with no luck. I need to get this fixed, because i cant drive on the freeway!! (combined with my exhuast leak im gettin about 9 mpg freeway lol)

anybody got any ideas as to whats going on? I know a decent amount about autos, but this stumps me and my dad, who was a mechanic for years.
Anything helps!
Ya'll have a good one, Andrew

z31freakify

if you don't want this problem to exist no more, here is a quick solution for those overdrive problems cause lets be honest no one has actually fixed this problem if someone did there wouldn't be so many people asking this same question, so here it goes 1st: disconnect one battery terminal 2nd:locate your ECT sensor 3rd:unplug the connector 4th: By-pass any of the two wires with a switch (you have to cut the wire for this procedure running one wire from one of the cut ends to the cabin of the vehicle where its going to be connected to one of the switch terminal and another wire from the other cut end into the vehicle to the other connection of the switch) The reason for the switch and this procedure is to disable and tricking the ECU into thinking that the motor has reach normal temperature, for some reason it makes your truck go in to overdrive even when the vehicle is cold and you can run it with this setup I did mine 7 months ago no problem what so ever just the service light on but once you hit the switch it turns off , the switch is for starting up the motor when it's cold if not you will take forever to start hope this helps many of you guys-gals with this problem don't spend hundreds you can do this for cheap and will fix that annoying problem for good: OHH also forget to mension Im new to this website and to toyota this has been a fun 4runner truck i bought a few months back soon will post pics of my rig and things i've done to it

scope103

Is your check engine light on? Your ECT (Engine Coolant Temperature) sensor is not working or is disconnected. http://www.autoshop101.com/ / Technical Articles / Electronic Transmission #1 / Page 6. If it's the sensor itself, that's about $50 at the dealer, $15 right now on eBay (89422-35010).

Since you can't afford to throw parts at your truck, you will test the sensor (and wiring) before replacing it. http://www.ncttora.com/fsm/1990-1995...e/engineco.pdf

Remember; the ECT sensor does a lot more than help the transmission. If it's not working your truck will have all sorts of problems. At least once the temperature drops below 70.

[By the way, just searching "o/d cold" gave me a bunch of hits; the first one was https://www.yotatech.com/forums/f116...roblem-194210/ ]

Pat8942

Check your TPS

z31freakify

I did put new ect sensor, tps sensor, water pump, OEM thermostat, flushed the cooling system, replace radiator and burped it, fan clutch, heck even the ecu, still no results, so doing this ect by-pass was my last hope and worked perfect till date works fine you just got to use that aftermarket on/off switch so you can start it up in the mornings. The service engine light will turn off if you flip the switch off (depending how you wire it example- OFF for ECT not working or ON for ECT working) this I only recommend for people that just give up in trying (just like me)