2006 GX470 transmission issues (2 Viewers)

[sidneyhop]

Around 200k miles and for a year or so Ive been having a delayed shift from R into D. I replaced the drive shaft and it seemed to help a little, but the delay was still there from time time. I also flushed the trans fluid and replaced the filter.
A few weeks ago it started delaying the shift from 1st to 2nd from time to time, and when it did shift it was sometimes a hard shift.
Within the past few days that delay has increased with higher rpms and seemed to be from 1st to 2nd, 2nd to 3rd etc. The shift points are not consistent and somewhat intermittent.

Could this be the torque converter or solenoid? Would a scanner detect specifically where the issue is?
Which replacement trans is compatible with the 06 GX? My understanding its the A750F but those were also used from 02-09 and Ill need one specifically from 05-09? FJ 4.0? 4runner? Also Id need to get one from a 4x4?
Thanks for any info!

 

[sidneyhop]

Just one code from the engine scanner pulled at Advance Auto Parts store. P2714 Pressure control solenoid D stuck off. (SLT Solenoid).

Installed a new SLT solenoid and also tested the old one (it was fine. 5.6 ohms and worked correctly with 12v applied)

Still having the same issues.

Any recommendations on additives that may help? Not sure if the previous owner used any and the seals have ballooned up or whatever so hesitant to add any, but at this point it probably doesn't matter.

Next step is to get a full trans scan if I can find an 'objective' place to get one. (most trans shops will lean towards "needs a full rebuild", as a default diagnosis)

Also, will all 05-09 4x4 A750F transmissions work in my GX470?
(Coming from a donor 4Runner, Tacoma (V6), Tundra, Sequoia, FJ Cruiser, Land Cruiser?)

Thanks

 

[Alleycats]

Spitballing here, but what about the obvious things like ATF level? Have you checked it per FSM?

 

[sidneyhop]

Spitballing here, but what about the obvious things like ATF level? Have you checked it per FSM?

yep....flushed the fluid and changed the filter. Its at the correct level.

 

[white_lx]

Just one code from the engine scanner pulled at Advance Auto Parts store. P2714 Pressure control solenoid D stuck off. (SLT Solenoid).
Installed a new SLT solenoid and also tested the old one (it was fine. 5.6 ohms and worked correctly with 12v applied)
Still having the same issues.

Maybe you can verify the resistance of the solenoid from the ECU connector? There could be a problem with the wiring harness. Especially the transmission connector is known to have corrosion and pin melting issues. By measuring from the ECU connector end, the integrity of the complete circuit can be checked.

 

[sidneyhop]

Maybe you can verify the resistance of the solenoid from the ECU connector? There could be a problem with the wiring harness. Especially the transmission connector is known to have corrosion and pin melting issues. By measuring from the ECU connector end, the integrity of the complete circuit can be checked.

Are you saying test connection going to the SLT solenoid? Do you know the correct resistance range?

That connection did look normal without any corrosion if thats what you're referring to.

 

[white_lx]

Are you saying test connection going to the SLT solenoid? Do you know the correct resistance range?
That connection did look normal without any corrosion if thats what you're referring to.

I was thinking testing the connection all the way from the ECU through the solenoid. That way you test everything. Not just the solenoid itself. However, I initially read your problem as P2716 (which is a resistance code). Yours is P2714, which is a performance code. Would still be prudent to exclude any connection issues before replacing the transmission. Attached it the procedure for diagnosing a P2714. It actually has you verify the resistance of the other solenoids first.

 

[Rednexus]

While I don't have any particular experience with this issue, I do remember reading somewhere that the solenoid harness inside the A750F can develop connection problems and require a replacement. It might be worth looking into. I think it was on a Tacoma forum.

It's actually very easy to replace the harness/valve body/solenoids on these transmissions....took me all of 3 hours when I installed the Nomad valve body.

 

[sidneyhop]

While I don't have any particular experience with this issue, I do remember reading somewhere that the solenoid harness inside the A750F can develop connection problems and require a replacement. It might be worth looking into. I think it was on a Tacoma forum.

It's actually very easy to replace the harness/valve body/solenoids on these transmissions....took me all of 3 hours when I installed the Nomad valve body.

Did you do the replacement with the trans in the truck? I dont have access to a lift other than jack stands.

Thanks!

 

[sidneyhop]

I was thinking testing the connection all the way from the ECU through the solenoid. That way you test everything. Not just the solenoid itself. However, I initially read your problem as P2716 (which is a resistance code). Yours is P2714, which is a performance code. Would still be prudent to exclude any connection issues before replacing the transmission. Attached it the procedure for diagnosing a P2714. It actually has you verify the resistance of the other solenoids first.

Thanks for the pdf. Im looking into it.

 

[Rednexus]

Did you do the replacement with the trans in the truck? I dont have access to a lift other than jack stands.

Thanks!

Just the valve body. You can definitely do that with jackstands. I wouldn't personally attempt the whole trans without a lift.

 

[sidneyhop]

Another error code. P0771 solenoid E stuck off.

 

[sidneyhop]

Just the valve body. You can definitely do that with jackstands. I wouldn't personally attempt the whole trans without a lift.

Was it worth the expense switching over to the Nomad? What were the biggest improvements?

 

[Rednexus]

Yes, but I tow with my GX a lot. It increased towing mpg by around 10-20%.

 

[sidneyhop]

A bit of an update.
I added half a bottle (12oz) of Lucas Stop Slip and for the rest of that day the problem disappeared. The result was almost immediate which seems to me the issue is with sticking valves and not seal related? The next day the issue came back only once in the morning when I first drove, then cleared up.

Does the sticking valve theory sound accurate?

 

[Rednexus]

You might want to head over to the 100 series forum and ask, as there are a couple of guys over there who know the A750F we share with those rigs really well.

 

[sidneyhop]

Unfortunately the trans 'fix' didn't last very long. Its back to not shifting into gear/delayed shift and engine RPM not going very high even though Im pressing the gas.

I recall reading that an engine issue can cause an error code that doesn't allow the trans to shift correctly. Does anybody have any info on what that could be?

I ordered a transgo shift kit, reg boost valve and accumulator piston for the valve body. Hopefully those help it towards a fix.

 

[sidneyhop]

Heres a bit of an update.
I did the full Transgo rebuild on the valve body and it still drove like s***. I then took it to the shop to hopefully get a diagnosis as to what the issue was and they did a computer reset as part of their process. Well, turns out the reset forced the computer to relearn the engine/trans conditions and now it drives great. The VB rebuild worked after all.
Hope this helps someone having the same issues I was having cause the VB rebuild is not expensive or very difficult either. Just be sure to reset the computer after!

 

[NJGX470]

Heres a bit of an update.
I did the full Transgo rebuild on the valve body and it still drove like s***. I then took it to the shop to hopefully get a diagnosis as to what the issue was and they did a computer reset as part of their process. Well, turns out the reset forced the computer to relearn the engine/trans conditions and now it drives great. The VB rebuild worked after all.
Hope this helps someone having the same issues I was having cause the VB rebuild is not expensive or very difficult either. Just be sure to reset the computer after!

That's awesome. If you could report back in a couple months to let everyone know that it is still working out.