"250"4-BY

I've never been a member of a forum... here it goes!

I recently bought an original owner '92 3.0 V6 runner with 168K on it. The truck is beautiful, but a very intermittent problem has come up. On a very long decent on the hwy, the auto (and I swore I’d never own an auto!!!) trans. kicks down a gear causing the engine to rev too high. The problem only occurs once or twice during a 3 hr hwy drive through the mtns(speed is usaully between 95-120K).

Even once on the flats it takes 5 or 10 mins to finally go back into overdrive (the trans was in overdrive the whole time). The trans shifts well and had bean on a regular service schedule when I bought it. Has anyone had this problem or a any suggestions??? Thanks for any help.

-Rob

Marc

Does this happen with the cruise control off or on?

frankenrunner

- bump - to "Marc", plus...

i would double check to make sure that the "overdrive" button on the gear shift lever is, indeed, pushed in & that i'm not, maybe, hitting it w/my knee or simply fiddling w/it absent mindedly because i, too, am use to a stick.

"250"4-BY

Hi Guys, I'm not in cruise when this problem occurs and I haven't umped the O.D. button. Also I can flick the button on and off with no effect during the problem.

ChickenLover

It sounds like an engine temp problem to me. You might be overcooling or your sensor might be on the fritz. You can not shift into O/D until your engine is at it's proper operating temp. During your decent, the lack of load on your engine is probably causing it to cool to a point below normal, causing it to lock out O/D until it warms back up.

"250"4-BY

ChickenLover, That sounds more along the lines of what I was thinking... I really don't think its a mechanical issue with the trans, but rather a funky sensor or something. Do you know where the temp sensor is located? This problem also occured at high elevation through the wintery mtns, so the temp drop is conceivable. Is the sensor in the trans. itself, or does it use engine temp? The engine temp. didn't drop all that much below normal on the long decent. Thanks.

mt_goat

I agree with Chicken on this. If you look at this link down a page or two there is a crappy little drawing http://personal.utulsa.edu/~nathan-b...34electron.pdf that shows the temp sensor near the throttle position sensor.

"250"4-BY

Thanks Mt Goat, thats a very handy little link.

mt_goat

Good, let us know what the problem was when you get it figured out. You are the second one I've seen that's had this problem. I never heard what it ended up being for the last guy. It's good if we can get feedback once the problem is fixed. Here is the index to the whole 93 truck FSM in case you need to find something else. http://personal.utulsa.edu/~nathan-b...fsm/index.html

mt_goat

Another thing to check is maybe your thermostat is stuck open.

frankenrunner

-bump- to "ChickenLover", i had'nt thought about the temp sending units inasmuch as i did'nt take into account " "250"4-by's" '(welcome to the site, by the way, it's a great place for 411)geographical location & i was actually starting to lean towards a problem somewhere in the "OD" wiring harness, which may be yet something else to take a look @, "250".
-f-

ChickenLover

It is located on the coolant bypass outlet (center of engine compartment near firewall). It's kind of underneath your plenum, so it's not easily accessible. Look at the pic below. There are a few sensors on it and I'm not sure which one it is. As Mt goat said, check your t-stat. If it is stuck open, that would be a cheap and easy fix.

"250"4-BY

Hi everyone,
I just wanted to thank all of you for your input on the trans. problem… I’ll definitely keep you posted on the diagnosis ad correction. It will be 3 or 4 weeks before I drive through the mtns again. Thanks!

-Rob