1990 not shifting into OD sometimes

[nmwolfer]

I have a 1990 4 runner and sometimes it will shift into overdrive and sometimes not. When it does, the extra power button works, it will run about 1800 RPM's at 55 mph and when I take my foot off the gas pedal, it will go down to around 1000 rpm. When it does not shift into OD, the extra power does not work, it runs about 2800 at 55 and when I take my foot off the pedal, the rpm's stay high.
I have taken it to my mechanic and he is having a hard time finding what the problem is.
Any help would be greatly appreciated. This is a vehicle that we use mostly off road here on the ranch, fixing fence and getting to where we need to go as this outfit will get us there.
Thanks,
Gary

 

[thatoneguy]

I have seen two automatic 3.0 V6's that will not shift into overdrive until they've been running for 10 or 15 minutes. I don't know what causes that kind of thing. Is your "sometimes" truly at random, or is it specifically when the engine's cold?

Die hard 3.0 fans here should be able to chime in. Guys?

 

[541joseph]

There have been quite a few threads that talk about it not shifting when cold. If it does to when it's warm you have issues if your truck never gets to operation temp you need at-stat does your truck warm up fully?

 

[fourwd1]

If it works then stops, then works, it could be the O/D solenoid is going bad.

It is a standard design that O/D is not enabled until vehicle coolant is up to operating temp.
This allows the engine to warm up faster, keeping emissions down.

 

[thatoneguy]

If it works then stops, then works, it could be the O/D solenoid is going bad.

It is a standard design that O/D is not enabled until vehicle coolant is up to operating temp.
This allows the engine to warm up faster, keeping emissions down.

Sounds a bit excessive to let the engine cruise like 3500rpm going 65 in the name of warming up. Weird design. I've also never encountered any vehicle newer than a 2nd gen that also adopts this "no O/D until it's warm" approach.

 

[nmwolfer]

It is random, sometimes it does not shift when it is cold, sometimes it does, same with when it is hot. When it will not shift, the extra power option also does not work and when it does shift, it does work.
I called the mechanic and let him know about the solenoid.
Thanks a million for all the help. I am hoping like the dickens that it is the solenoid. It does have a new tranny in it, so I think I can eliminate that. When it does shift, that son of a gun runs like a clock. I am off road with it, more than on but the biggest thing is the gas mileage, I only get 13 mpg. All that high rpm's takes a heavy toll on the mpg.
Thanks A Million,
Gary

 

[fourwd1]

Sounds a bit excessive to let the engine cruise like 3500rpm going 65 in the name of warming up. Weird design. I've also never encountered any vehicle newer than a 2nd gen that also adopts this "no O/D until it's warm" approach.

Every auto trans vehicle I own/haved owned does that.

 

[laxbro19]

I wouldn't be complaining about 13 mpg. With dd between school and work I average out at about 11 mpg and with strict highway driving I get 15 mpg. I also have the same problem with my auto trans not shifting but it only happens when it's cold. Once it warms up to running temp it shifts fine

 

[reallifedog]

I didn't have this issue until I replaced my A/T cooler. I only lost like a 1/4 cup of fluid and haven't replaced any since it still looked good(red).

 

[nmwolfer]

I have been trying to order an overdrive solinoid kit, does anyone know the part number or where I can order one.Thanks

 

[fourwd1]

Did you pull the trans codes when it wasn't working to verify it is the solenoid?
It would be error code 64.
Then check for the trans code at the bottom of the VIN plate to determine exactly which version you have. Then Google to find best deal.

For example, Bulkpart.com has one for most A340 models for $75

 

[nmwolfer]

I took it to the shop and when they checked for error codes, there was none.
What it does is sometimes it shifts and sometimes it does not. When it does shift it will stay in overdrive for a few miles, then shift out. It does not matter if it is hot or cold. I have started out with a cold engine and it would shift into overdrive fine, then sometimes start out with a cold engine and it would not shift. When it does shift into over drive, the extra power button works. When it does not shift the extra power does not work. We have a ranch up on a fairly high mesa and the road up here has several switch backs and is steep. When it is shifting and I push the extra power button on for a boost in power getting to the top I can really feel the boost in power but when it is not shifting, there is no boost. When it is shifting, if I let off the gas pedal, the rpm's will drop down to 900, when it is not shifting, and I let off the gas pedal the rpms, will drop to anywhere from 1800 to 3000. That is how I can tell when it is shifting, when I let off the gas if it goes down to 900 I know it is shifting, if not then it is not shifting.
Thanks A Million For Your Help,
Gary

 

[fourwd1]

How did the shop check for codes? A scanner won't do it, you have to jump 2 terminals (not the same ones as for engine codes) and count flashes of the OD light.

As far as the "Power" button not working at the same time, I'd have to look into that.
I don't recall if that should be affected or not.