Trans doesn't shift past 3rd

This is my first post, and unfortunately for a transmission issue. My truck is getting older, so I'm sure I'll be on here more as time goes by.

I have a 2006 Tacoma Pre Runner sport, SR5, quad cab with auto trans. I'm the original owner and has 337,000 on it. I don't tow anything, heaviest load is a dirt bike and some gear etc. I don't run it hard.

So, the issue is, today, I drove it and was fine, get back in a couple hours later and it will shift and feel normal up to 3rd gear and wont go past. No noises or jerks, just wont go past 3rd. I was hoping it might be low fluid, I haven't checked it in a couple years, but it doesn't leak. Unless it does while driving. Every once in a while, after a long drive, I might see a dime size spot, but that's it. The trans has never been serviced, mostly because the dealer refused to do it every time I asked. The last thing I did a couple years ago was check the level as best I could, crossing over contacts under the dash with a jumper wire method, and add some Lucas treatment.

Any suggestions on where to start.

Thanks.

 

Check the fluid level again
Scan it for codes

This is a long shot but I've seen clogged catalytic converters inhibit airflow and engine rpm to the point where the the trans won't shift

And welcome to TW

 

Welcome to Tacoma World. That’s a lot of miles to have never been serviced. If it was mine I’d drain and check fluid, drop the pan, replace the filter, and do a flush. Others will tell you “it’s old don’t change it!” You’ll have to make your own choice on that but I wish you good luck.

 

I'm assuming you have the V6 with the A750 transmission, there's alot of info about it in the thread below.
Do you have a check engine light on, does your shift indicator work properly on the dash?
https://www.tacomaworld.com/threads...th-pics-for-second-gen-4-liter-trucks.289913/

 

The guys above asked the important questions and they are 100 % correct

These transmissions will not shift past 3rd gear if the check engine light is illuminated or transmission codes are stored in the trucks computer .
You have a completely computer controlled transmission . A scan would be in your best interest .
If you post up the codes , we can try and save you some cash .
What are the chances you have a scanner ?

 

^^^Listen to this man, I have read a lot of his posts. He is the transmission wizard!

 

Thanks everyone for the quick replies. And, I do happen to have a cheap HF scanner. I have a P0174 and a P0776. So it looks like possibly a solenoid? If it is, is this a basic swap? I'm guessing it's a drain and pan removal. If so, here are my questions ahead of time.

Will I need a pan gasket
How much fluid will I need and should I use the WS Toyota, or is there something else that is fine.
Can I easily access the filter while it's open to clean.

Would it be okay to drive side streets, no freeway for today. Short story, I'm under pressure because do in home repairs, and have several customers scheduled for today. It would be easier to do this tomorrow with less time pressure. Really don't want to have to re schedule as some have been waiting for parts for months.

Thanks again, Rick.

 

I'm betting the problem is electrical, not mechanical. I've seen transmissions do weird stuff because a mouse chewed insulation off a wire. All that was required was to put some shrink wrap over the exposed wire.

Servicing the transmission at this point is a waste of money. If the transmission is still good changing the fluid won't hurt, or help, anything. But if it is already compromised keeping the old fluid in there will buy you some time before it goes out completely. Your dealer was giving you good advice refusing to do the work. You're going to need a new one, or a rebuild, in another 100,000 miles or so and that would be true even if you'd changed the fluid every 30,000 miles.

And it is also possible that the transmission is gone, but I doubt it. Somewhere around 400,000 miles is pretty typical whether they are serviced or not, and you're getting close so even if it is gone you can't really complain.

 

Okay, it sat overnight. I cleared the codes, let it warm up and it’s working now. Aside from the being old part, does that change, or confirm anything. I don’t have the money for a rebuild or replacement right now, so I have to throw some Hail Mary’s at it to buy some time.

 

Hi Rick

You will need a digital volt ohm meter . As mentioned P0776 trips when the computer in your truck sees a problem with the pressure control solenoid .
Next step would be to locate a new solenoid from Toyota or Rostra . They are pricey . Last one I purchased was 300 bucks
You can do the resistance check from outside the transmission where the wiring goes into the transmission case . This can be done without removing the transmission pan .
You will also be looking for green death . Green death is the corrosion you find where electrical components join together . Water always finds a way in causing problems such as this .
If you dont find green death ,You will need a pan gasket to change out the solenoid and look for shorts in the internal wiring harness .
Considering you can clear the code and achieve 4th gear leads me to beleive you have high resistance in the solenoid wiring circuit .....green death
You will need replacement fluid for a pan drop . 6 quarts of WS will work .
You can drive your truck in 3rd until you have a chance to fix the problem .
https://www.tacomaworld.com/threads/auto-trans-not-shifting-passed-3rd.695647/page-4

 

Thanks for the info. I'm just getting a chance to get back to this, it's been working since I reset the code. With all the rain we've been having lately and the two holiday weekends, it's slowed me down. I'm always busy taking care of everyone else, I don't get a lot of me time. I'm checking the fluid level today, and will check the plug. I do have an ohm meter, but only skilled at the basic functions, what setting should the meter be on for the test.

 

Okay, I’m doing the level check and the light keeps blinking, it can’t be hot. When I do the shift cycle, the light comes on, but blinks when input it in park. I let it sit for about 30 min and it’s 50 degrees out. Now it’s getting dark and I have to drive it to LA tomorrow. I’ve already put a about 1/2 at in. What now.