Signs of A340F transmission going out

[nathanroyse]

My transmission has about 200,000 miles on it currently and is starting to have some hard shifts pretty often. When I down shift it’s not always the smoothest coming out of 4th gear. Has anyone experienced this before and is it something that can be fixed? I’ve done a couple drain and fills and tried adjusting the kick down cable but neither has helped. It has never not shifted or lost a gear. Is it time for a rebuild/new transmission? Or just a flush and maybe new solenoids and a filter. Also, when coming to a complete stop, after letting off the brake petal, it clunks. Almost like it doesn’t shift all the way back down to 1st gear before coming to a stop.

Anything helps, thank you.

 

[thegipper]

Make sure the fluid is at the correct level and the fluid itself is in good condition. How did the fluid look when you started replacing it?

To properly check the level, take the truck on a 20 minute drive, preferably in town/city so you are stopping and going a bunch. Then park the truck on a level surface and leave it running. Shift between each gear and leave it in each gear for 5 seconds. Once you have gone through all of the gears, put it back in park and check the fluid level. The fluid should be at the top of the "hot" mark on the dipstick. Adjust the level accordingly if needed.

It wouldn't hurt to drop the pan and see how it looks. Other things you can try is replacing the filter and solenoids. Beyond that, there really isn't much more you can do.

The 96-00 transmissions are pretty bullet proof. The 01-02s are a little more prone to failure because of planetary gear failure.

If after everything is clean/new it still shifts hard, just keep in mind that you may need to replace/rebuild the tranny at some point.

Good luck

 

[jgue467]

What product did you drain/fill with?

My nasty 01 had a significant whine in 1st and 2nd, less so in 3rd. Dropped pan, changed filter and refilled with valvoline full synth import. Still had whine for a couple thousand miles then it just went away, hmm. Wasn't expecting that but it shifts firmly up, smoothly down. Just a thought, sometimes more fluid changes can help, so now I try not to wait 100k like I did this time, ugg.

 

[Bad Luck]

Typically when a transmission starts failing you get slipping, longer shifts, spongy shifts and not firmer shifts. Try loosening your line pressure control cable (commonly mistaken for the "kick down cable")

 

[nathanroyse]

Make sure the fluid is at the correct level and the fluid itself is in good condition. How did the fluid look when you started replacing it?

To properly check the level, take the truck on a 20 minute drive, preferably in town/city so you are stopping and going a bunch. Then park the truck on a level surface and leave it running. Shift between each gear and leave it in each gear for 5 seconds. Once you have gone through all of the gears, put it back in park and check the fluid level. The fluid should be at the top of the "hot" mark on the dipstick. Adjust the level accordingly if needed.

It wouldn't hurt to drop the pan and see how it looks. Other things you can try is replacing the filter and solenoids. Beyond that, there really isn't much more you can do.

The 96-00 transmissions are pretty bullet proof. The 01-02s are a little more prone to failure because of planetary gear failure.

If after everything is clean/new it still shifts hard, just keep in mind that you may need to replace/rebuild the tranny at some point.

Good luck

Thank you for your input. I checked the fluid level and it’s just barely above the top of the hot. I will make sure to measure it more accurately when I add the cooler. When I started replacing the fluid it was dark. But when wiped on a paper towel, was still red. I am going to open the pan next week. Mine is a 2000 so hopefully it just needs some adjusting. I also noticed that driving around town, the transmission would get up to 240 degrees…


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[nathanroyse]

What product did you drain/fill with?

My nasty 01 had a significant whine in 1st and 2nd, less so in 3rd. Dropped pan, changed filter and refilled with valvoline full synth import. Still had whine for a couple thousand miles then it just went away, hmm. Wasn't expecting that but it shifts firmly up, smoothly down. Just a thought, sometimes more fluid changes can help, so now I try not to wait 100k like I did this time, ugg.

I used valvoline maxlife atf. The red bottle. I have no whine whatsoever… which is why I still have hope.


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[nathanroyse]

Typically when a transmission starts failing you get slipping, longer shifts, spongy shifts and not firmer shifts. Try loosening your line pressure control cable (commonly mistaken for the "kick down cable")

I’ve messed with it a couple of times, but I’ll give it a shot again. It seems to not like to downshift completely when coming to a stop when it’s loose. How directly related to the throttle cable is the line pressure control cable? Is it possible for one of them to be too tight/loose and is just messing everything up?


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[Bad Luck]

I’ve messed with it a couple of times, but I’ll give it a shot again. It seems to not like to downshift completely when coming to a stop when it’s loose. How directly related to the throttle cable is the line pressure control cable? Is it possible for one of them to be too tight/loose and is just messing everything up?


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The only thing that cable controls is line pressure in the transmission which determines how firm or soft your shifts are and will also increase line pressure as throttle position increases. If it's too tight it will give you very firm and hard shifts even at lower throttle. Try loosening it an 1/8" and seeing if that changes anything.

 

[nathanroyse]

The only thing that cable controls is line pressure in the transmission which determines how firm or soft your shifts are and will also increase line pressure as throttle position increases. If it's too tight it will give you very firm and hard shifts even at lower throttle. Try loosening it an 1/8" and seeing if that changes anything.

Okay. Will do. I just read through the factory service manual and found the transmission testing parts and will do all of those as instructed and see what I can find out.


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[gamefreakgc]

The only thing that cable controls is line pressure in the transmission which determines how firm or soft your shifts are and will also increase line pressure as throttle position increases. If it's too tight it will give you very firm and hard shifts even at lower throttle. Try loosening it an 1/8" and seeing if that changes anything.

Yes, there's a little knob in the cable at the throttle body that indicates the tightness (or looseness) of the line. I actually prefer mine a tad bit overtightened which does result in firmer shifts, especially the 4th to 3rd downshift under heavy throttle.

I also highly recommend a quality synthetic fluid. Redline is very popular, I went with Royal Purple and got similarly great results. Much softer shifts and better transmission operation. It really is a win-win and beats out even OEM Toyota transmission fluid.

 

[vegask]

Been a while since I flushed mine, but I used mobil 1 synthetic. If you are planning on dropping the pan to clean the magnets and filter. You may want to consider replacing the solenoids also.

 

[nathanroyse]

Yes, there's a little knob in the cable at the throttle body that indicates the tightness (or looseness) of the line. I actually prefer mine a tad bit overtightened which does result in firmer shifts, especially the 4th to 3rd downshift under heavy throttle.

I also highly recommend a quality synthetic fluid. Redline is very popular, I went with Royal Purple and got similarly great results. Much softer shifts and better transmission operation. It really is a win-win and beats out even OEM Toyota transmission fluid.

Okay. I know what you’re talking about and I will adjust it. When I flush my fluid I will also refill with Royal Purple. Which one did you use?


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[nathanroyse]

Been a while since I flushed mine, but I used mobil 1 synthetic. If you are planning on dropping the pan to clean the magnets and filter. You may want to consider replacing the solenoids also.

Are the solenoids hard to get to? Is it okay to change them yourself?


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[spartacus]

Are the solenoids hard to get to? Is it okay to change them yourself?


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There are on the valve body with wire going to them, you can't miss them.
Shift solenoid code

 

[Jvilotti_t4r]

My 96 trans went out and I did experience hard shifts when driving hard or in the hills. And It was shifting extremely hard right before it completely let go.
After the rebuild I installed a temp guage and with the temp spikes I was seeing learned very quickly I probably cooked it. I then installed a trans cooler and have now never seen it above 180
So +1 on temp guage and cooler after a good flush

 

[Bad Luck]

There are on the valve body with wire going to them, you can't miss them.
Shift solenoid code

I'm pretty sure there is one or two shift solenoids above the throttle body as well.

 

[nathanroyse]

My 96 trans went out and I did experience hard shifts when driving hard or in the hills. And It was shifting extremely hard right before it completely let go.
After the rebuild I installed a temp guage and with the temp spikes I was seeing learned very quickly I probably cooked it. I then installed a trans cooler and have now never seen it above 180
So +1 on temp guage and cooler after a good flush

Oh man, that’s kind of what I’m thinking too, that I cooked it. It’s not super hard but it’s definitely abnormal. I will flush and install a cooler. Did you replace the trans? Or rebuild?


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[spartacus]

I'm pretty sure there is one or two shift solenoids above the throttle body as well.

AFAIK. There are 4 on the Transmission valve body 3 shift and one lockup.

 

[gamefreakgc]

Okay. I know what you’re talking about and I will adjust it. When I flush my fluid I will also refill with Royal Purple. Which one did you use?


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I used their MAX ATF product. I think I got it at Wal-Mart, they also sell Redline products too. Either of those two are top-notch so choose whichever is cheaper. If you are doing a flush, you'll need a lot of fluid as opposed to a drain and fill. I did a series of 3 drain and fills and used 12 quarts. If you've never flushed it before (can't remember) the supply hoses can be extremely difficult to remove off the hard lines. Mine were frozen so rather than risk damaging the lines I did drain and fills.

 

[gamefreakgc]

AFAIK. There are 4 on the Transmission valve body 3 shift and one lockup.

There are 3 total. Two controlling the gears and a third for lockup. Solenoid No.1 and Solenoid No.2 use a sequence of On-Off, Off-On, On-On, and Off-Off to control all 4 gears in the transmission.