I could use some advice here. I'm new to the 4runner world and just started having this issue a couple of days ago. I have a 93 4runner SR5 with a 3.0 V6. A little background, I just got this one from a guy a guy who rebuilt the transmission about 4000 miles ago, but 4 years ago. He drove it about once a month to keep it from sitting. So my issue is I cannot shift into 4th on the highway. I looked into it on here and people said it's either the engine not warming up enough to allow it to switch or the automatic transmission solenoids. The solenoids were changed on the engine rebuild, and after about 20 minutes of diving it as gently as I could on the highway while it was running around 3k rpm it still wouldn't shift. I opened the hood and some steam came out and I could tell that the engine was hot, not terribly over heated but getting up there. So I thought it might be the temp sender as opposed to the thermostat. I currently have a 195 degree thermostat, temp sender and temp sensor on order and am waiting to put those in. Does anyone have any thoughts on this?

 

Welcome to YotaTech.

You probably have the A340H transmission. (Look on the door pillar and get back.) That's a 3-speed transmission, so I assume what you don't have is overdrive. The O/D Switch should be on the shifter. Toggle it, and the O/D Off light in the combination meter should come on. If it doesn't, something is broken in the switch or indicator or other circuit. Do you have the Pattern Select switch? That controls shift points, but shouldn't prevent O/D, but still you should try it.

Check for codes: http://web.archive.org/web/201408161...31diagnosi.pdf (you'll need a working O/D Off light for this.).

 

Thanks! You were right, I do have the A340H. I don't get any light regardless of the OD position. I was just out driving it to see if I could narrow down the symptoms and it suddenly started working again for a bit. It seems the problem is intermittent, which definitely does sound electrical. So are those temp sensors and thermostats unnecessarily then? I'm not sure about the pattern select switch, but I have an ECT/PWR switch that doesn't seem to do anything, but a light does come on when I push it.

 

if you have the gauge, you have at least three temp sensors: ECT, temp gauge, and a/c shut off (4wd only) (plus the CSI time switch, but that doesn't really work as a sensor). Do you know which ones you ordered?

You'll have to figure out the O/D light. It could be as simple as a burned out bulb (which would be an issue, because you can't tell when you're in O/D Off). Or a wiring issue which could hold it in O/D off. Also, you won't be able to read the codes, so you could have a bad solenoid or just about anything in the O/D system. You could have dirt somewhere in the transmission that is interfering with the pressure control. Add to that "a guy who rebuilt the transmission about 4000 miles ago, but 4 years ago" and you may have a challenge ahead of you.

You could ask if O/D ever worked, but I would be surprised if the answer would do you any good.

Both O/D and lock up are inhibited when ECT below 70°C. Are you sure it's an O/D, and not lock up, issue?

ECT/Pwr is the pattern switch. What it should do is delay shifts when in the Pwr position.

Good luck!

 

I'm not sure if it's an O/D issue or a lock up issue, but I think it's the O/D. However and weirdly, if I turn the heat on, it works perfectly fine. I just happened to read that on another forum and tried it, and it worked, so I think it is a wiring thing. Thanks for all the advice by the way!