4mydogs

That makes sense. I am going to stop by my friendly neighborhood transmission shop and talk to them -- try to get a feel for how they will go about diagnosing this. I really like this truck, and I plan to keep it a long time, so I want to get this problem solved.

mt_goat

Go back and reread Gadget's post. You can't buy advice that good, maybe he will go into more details on how he traced the problem down to the converter clutch solenoid.

MTL_4runner

That info is all the the Factory Service Manual.....you absolutely need one if you are going to do the diagnostics yourself.

mt_goat

You may want to install a temp gauge for the ATF. My light has never come on, but I'd like to know what the temp is before it gets too hot.

4RUNR

I'd imagine that checking speed vs. rpm would tell with fair certainty if it is locking up or not.

4mydogs

OK, I went and spoke to my as-it-turns-out-not-so-friendly neighborhood tranny man, who basically told me to go see my Toyota dealer. Hmmm... Anyway, since the dealer is a good hour+ drive and it doesn't seem like I'm going to find a good diagnostician locally ("Is it slipping? Then there's probably nothin' wrong with it.") I called the nearest Toyota dealer and ordered a replacement sensor. I spoke with my regular Joe mechanic who is going to do a flush and replace the sensor for me, and isolate the trans cooler in the bottom of the radiator and make sure it isn't clogged. Then it's road trip time and see if it happens again. If this takes care of it, then I'll be looking to install a trans cooler anyway, to hopefully prolong the life of it. Q: My Haynes manual doesn't even show the location of the sensor, but the parts jockey told me it goes "on top of the transmission," so how tough is it to replace one of these? Has anyone done it and can tell me? Thanks again, one and all!

Reldnew

Simple torque converter lock up test:
On a long flat or slight downhill, set the cruise (or use a steady foot on the gas) at about 60mph. Engine should be all settled down into it's low rpm cruise mode. Apply medium pressure to the brake pedal while maintaining speed. If the tach does NOT jump up about 2-300 RPM, your torque converter is not locking up.

Also check the sensor-I don't have the specs handy but will check them when I get to the sop tomorrow.
Good Luck

4mydogs

Sounds like a good idea, Reldnew! I'll be going on a drive Wednesday after work where I can try that out.

MTL_4runner

If you are going to troubleshoot the tranny you really need to get yourself a genuine Factory Service manual. The Haynes manual assumes tranny's are a job for professionals only so no info is given.

Here are some more links for ya:
http://www.autoshop101.com/forms/h16.pdf

4mydogs

Great link! Thanks, MTL.

4mydogs

I finally got out of town last night and got up to 60 mph, revving just above 2500 rpm. As soon as I pressed the brake the engine revved up to almost 3000, so I guess my torque converter is OK. The sensor I ordered should be in today.

MTL_4runner

You might also want to take a look at this thread where we did alot of tranny diagnosis on this one.
https://www.yotatech.com/forums/f16/automatic-transmission-problems-need-help-16332/

......but check the temp sender to ensure it works properly first.

4mydogs

Wow! That's one heckuva thread. And I thought I had a problem! Fortunately my transmission exhibits no similar symptoms. The trans fluid level and condition is OK, and I cannot detect any slipping. The dealer called: the new sensor has arrived. Unfortunately it doesn't look like I'll be able to get to the dealer until next week to pick it up (too far away, and they close before I get off work). In the meantime we'll be packing up and driving to a dog show about 2 1/2 hours away this weekend. Wonder if that light will come on again . . .
Thanks for posting that thread -- I'll update when I know something.

4mydogs

Follow up: The Light came on twice on the trip, once going and once coming. First time after driving a little over 100 miles on I-16 in Georgia (nearly all flat), and on the return trip at 135 miles. It was 90 - 95 degrees and I was running a/c, doing 70-72 mph. After 15 - 20 minutes idling on the shoulder the light went off and didn't come on the rest of the day, just as in previous instances. (Once it has done it's thing, it does not do it again -- until the next trip.) I made the 2 hour trip to my Yota dealer today and picked up the sensor, no more than an inch and a half long, bolt on one end and plastic piece w/ an o-ring on the other. They said "it just screws into the top of the transmission." That sound about right to you all? My regular mechanic is going to do a trans flush, and somehow make sure that the trans cooler in the bottom of the radiator is not clogged, and install this new sensor, tomorrow. Any thoughts before I turn him loose on it?

mt_goat

You may want to drop the pan and change the ATF filter too. If you do drop the pan that would be a great time to install an after-market ATF temp gauge since I believe you have to drill a hole in the bottom of the pan for the sensor. That way you'll have more than just an idiot light.

4mydogs

That's a good idea. I suppose he would need a replacement gasket as well as the filter. As for a temp gauge, how high should it read (what is "normal" operating temp for the trans)?

mt_goat

The filter kit I got from Autozone had the filter and a gasket but I didn't even use the gasket, I used some Great Stuff gasket maker. Toyota doesn't use a gasket either, they use some red stuff. As for the temp, I don't know. I think Gadget's site might have that info. http://www.gadgetonline.com/TransFlush.htm

MTL_4runner

Just use some high temp RTV (Orange, black, blue, etc) and make sure to clean the pan well (esp gasket surface) before reassembly.

4mydogs

What a day this has been! My mechanic flushed the transmission, check all lines for blockages and found none, dropped the pan, did the filter, and when he went to find the sensor and replace it with the one my Yota dealer provided . . . couldn’t find it. I called to see if the dealer’s parts guy I spoke to (let’s call him parts guy number 1) could fax a diagram showing the location, only he couldn’t because he no longer works in parts. He’s in sales. A good place for him, since he sold me a part that doesn’t fit my Runner. But before parts guy number 2 told me that, he told me he couldn’t fax me a decent diagram because they don’t have very good diagrams in the parts department. (This even though parts guy number one distinctly told me that he looked at a diagram in the parts department showing THIS SENSOR fitting into “the top of the transmission.”) The service department, number 2 explained, has much better diagrams, so I asked him if I could speak to someone in service. “No,” he answered. You see, if they let service guys speak directly to parts purchasers, it would take too much time away from their duties in “service.” They “will not let service personnel speak on the phone,” parts guy number 2 told me, in no uncertain terms. He put me on hold, and finally came back with parts guy number 3, who he said, if anyone could figure it out he could. There are two (according to parts guy number 3) temperature sensors for my trans, and neither one is the one that parts guy number 1 sold to me. After I went to a better place and regained my composure, I asked number 3 what could I do? “Bring the vehicle into our service department,” was, of course, his answer. . .
I love what you do for me Toyota!
Well, at least I have fresh trans fluid for this weekend, in case we evacuate for Frances.

Gadget

On the 3rd Gen 4Runner which I think uses basically the same tranny, the over temp switch is located on the passenger side of the tranny. It is in the fitting that connects the tranny cooler out line to the tranny.

Gadget