AKTaco

I have an 02 Tacoma, V6, A/T, TRD with 39K miles. Check engine light came on this week after gradually accelerating from a complete stop. Dealer says the above error code is the culprit and hands me an $800 estimate to replace. Not covered under tranny warrantee since it's an electronic component and bumper-to-bumper ran out 3K ago. They also say they need the truck for a full day to pull the pan and test the solenoids individually to determine which of the three is bad, and for another full day to R & R once the part comes in.

Truck appears to be shifting/running normally, based on tach, sound and feel. It gets VERY HEAVY city use, lots of idle time (5-10 minutes per time, 15-20 times a day) and is on the road 8-15 hours per day, with about 3K a month worth of city miles. Almost always in 4H due to icy, snowy roads.

Dealer says it's okay to drive in the meantime until service is done... so, why does it need to be changed at all? What exactly does this solenoid do within the tranny? Why would they need to pull and test all three... doesn't the "A" indicate that it would be the "A" or #1 solenoid?

Thanks for any insight you can provide.

SouthGaRunner

I've been driving my 94 runner for about 8 or 9 months with the same problem, I just don't have the time while I'm in school. Do a search..I remember someone with the answers for you.

Gadget

You can do most of the checks outside of the tranny. It will tell you where the fault lies. My guess because you say the tranny is operating normally as far as you can tell is that the converter clutch solenoid has gone bad.

Unless you know what you are looking for you will not notice a failure of the converter to enter lockup mode.

This happened to me and I followed the diagnostic proceedure listed in the FSM for that code and it quickly lead to a bad solenoid.

To replace it is very simple, drain and drop the pan. Reomove one bolt and plug and teh solenoid comes right out. Then the new one goes in just as easy.

The hard part is getting the correct one from the dealer. They kept ordering me the wrong one even when I pointed to the right one on the screen. When I finally got the right one everything was fine.

So, the first place to start is to follow the diagnostic proceedure listed for that code.

AKTaco

Thanks for the info... once the code is reset, and the check engine light goes out, will it come back on within a few hundred miles if the solenoid did in fact fail, rather than just had a hiccup?

MTL_4runner

If the solenoid was in fact the culprit and you reset the CEL, then no, it will not come on again unless something else goes wrong.

This might help you a bit with understanding what the solenoids are and how they function.
http://www.autoshop101.com/forms/h16.pdf

As gadget mentioned, be sure to get the correct one.....the install is relatively easy.

Babypig

So these aren't covered under warranty. Man I'd be hoppin mad. It's bolted to the tranny. It's in the tranny. I've replaced a couple on my second gen but it's 15 years old. And you're only 3000 past the b to b. I'd raise hell and call Toyota corp and see what they'll do.

AKTaco

Thanks for the link, MTL... exactly what I was looking for. After 15 years as an aircraft engine mech, I know what solenoids are, just not how/where they were involved here, and how it could fail, but the system still functioning normally. The fact that the two are working in conjunction and are basically redundant answers that question. Nice to know the install is relatively simple too, as opposed to the 16 hour project the stealer wanted me to believe.

Yes, Babypig, lets just say I was more than a little peeved that it's not considered part of the tranny, when it is an integral part of the transmission system. In 20 years of Toyota ownership (my first car was a '72 Carina), I've only had two major issues that I went to the dealer for... the first time they wanted to charge me $1500 to replace all my injectors and an airflow sensor. I told them to put that truck ('87 SR5) back together and I would come get it... had an aircraft electrician buddy take a look at it... turned out to be a corroded ground wire on one injector. Cost me half an hour and a 6-pack to get it fixed. Since this is the first Yota I've rolled off the showroom floor, I was all freaked out about doing anything to it myself that might void the warrantees.... what waranttees??!!!?! From now on, I'll just go back to what I've done with every other one over the years... fix it myself or bribe my bud's with Buds.

AKTaco

PS: The most important thing is that it passed the I/M emissions test yesterday, so now it's got a fresh registration again!

MTL_4runner

Glad I could be of help.

Just for the record the solenoids are not truly redundant, the first 2 work in tandem like a logic gate (ie the 1 or 0 similar to a computer). By having one on or off at any given time will tell the tranny which gear to be in because there are 4 possible combinations they can be in. If your tranny shifts fine, don't worry about these.

Now there are 2 more, one is a lockup for the torque converter and the other allows 4wd shifting (you may not have this one if you have 2WD). If the dealer said your converter is not locking up then the 3rd solenoid is likely the culprit (not always, but usually). Also be sure to read pages 13 and 14 as well regarding the lockup of the converter and what conditions must be met.

Babypig

Can you still pull the codes for the tranny like you can with the second gens or does that go through the OBDII diags as well? There should be a code that you can trace back to the specific solenoid. Just wondering is all.

AKTaco

Thanks again, guys. The OBDII code that originally came up was P0750 "Shift Solenoid A malfunction" which common sense should tell me is the #1 solenoid, but I'm sure it's possible that the "A" refers to something other than position or "firing order" (for lack of a better term).

So far, I have run it through every setting I can think of: 2H, 4H, 4L, shifting manually, ECT normal/power, O/D on/off, gradual acceleration at both low temp and normal temps, romping on it in all of the above scenarios, and cruise control on/off in various scenarios. Everything seems to be perfectly operational... I've put about 400 miles on it since the original indication.
After talking with several other mechanics, I'm thinking that it was just a momentary glitch in the system- or more likely that a piece of sludge/dirt/debris got caught in the solenoid and kept it from closing completely just long enought to trigger the error light. The light came on immediately following the 2-3 gear shift, which leads me towards the #1 solenoid even further. The stealer had just performed the first hydraulic fluid change a few weeks prior, hence the theory that it knocked loose a piece of something that bound up the solenoid drain from closing completely.

Either way, I guess I'm not going to sweat it until/unless something else happens to make me think it wasn't just an isolated incident.

Babypig

If it's anythig like the a340h then the code will be triggered due to electrical fault not mechanical. More than likely a bad solenoid. They aren't that hard to change, just a bit of a pain.