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Transmission doesn't shift past 3rd, P0761, Sonnax end plug kit
Hi from Australia.
About a year ago, I bought an IS250 RWD with 220,000km on it. As I do with most 2nd hand vehicles I buy, it gets a full service including all fluids shortly after purchasing. I drained and filled the trans with Toyota WS fluid until it looked pretty red. The oil was dark but didn't smelt burnt.
On the test drive after the fluid change, the P0761 code came up. I realised now that it was a pretty common issue with the 2IS auto trans. I went ahead and changed out solenoid C with a genuine part from PartSouq but the problem didn't go away. It also got a new pan gasket and filter. The magnets were cleaned out too. I don't believe the previous owner has changed the trans fluid prior to me purchasing it.
The symptoms are that it wouldn't shift past 3rd gear intermittently. Most of the time, it drives perfectly fine with no issues up or downshifting. When it doesn't shift past 3rd, the revs goes up higher than normal. I would then flick the lever over to S, pull the lever down to 3 and back up to 4. The transmission will then shift to 4. I would flick the lever back to D and the car drives normally again shifting up and down as normal. The CEL doesn't usually correspond to the occurrence of this symptom either.
I wasn't sure of fitting a used transmission as most would have quite a few miles on it anyway.
The Toyota/Lexus A761, AB60 and A960 6-speed transmissions have been showing up in shops more frequently over the last couple of years. Warranties are expiring and people seem to be hanging on to their vehicles longer these days. Even so, there are a number of different issues with these transmissions, including torque converter clutch failure that is especially chronic with AB60 Tundra applications. Common to all these units is a problem that sticks out a bit more than the others, though: On-Off solenoid mechanical fault codes. You’ll see these as P0751 S1 solenoid performance, P0756 S2 solenoid performance, P0761 S3 solenoid performance and P0766 S4 solenoid performance codes.
These types of Diagnostic Trouble Codes (DTC) set when the Transmission Control Module (TCM) commands a specific gear and an incorrect ratio is shown from the input and output speed sensors. As an aid for diagnosis, the TCM will set a DTC related to the solenoid or combination of solenoids responsible for that gear ratio. This can be a tricky situation, as the same performance codes also can set when a clutch in charge of holding the gear ratio is slipping or neutraling out. Immediately throwing new solenoids at the problem can be an expensive mistake if the clutch actually is to blame. The key to diagnosing the problem right the first time is verifying solenoid commands and gear ratios with a thorough road test and capable scan tool.
The trouble area that these three transmissions have in common relates to the feed that these solenoids are provided. On-Off solenoids typically are fed reduced pressure from a solenoid modulator valve or fed line pressure through a very small orifice to prevent flooding. Oddly enough, these 6-speed solenoids are fed regulated, non-orificed line pressure from the manual valve. You can count this as your little-known and even less-cared-for fact of the day, but it’s an extremely important one.
The significance of the unusual feed system is where our problem lies, because there is another On-Off solenoid connected to same oil circuit feeding the solenoids: the SR solenoid. This particular solenoid does not have a performance code connected to it to aid in diagnosis. The fact of the matter is that the trouble codes listed above really are of no help other than pointing us to the solenoids. The actual problem is deeper…it is the solenoid feed.
Figure 1 shows the locations of S1, S2, S3, S4 and the SR solenoid where you can see an exhaust port deeper in the bore from the SR solenoid. This port is directly below the retainer pocket for the bore plug located behind the SR solenoid Figure 2 shows the OE bore plug and retainer removed from the valve body This bore plug separates solenoid feed (line pressure) and a circuit that is charged in first through fourth gears (Figure 3).
The kit containing various O-ringed end plugs is only around AUD30. However, it looks like the valve body needs to be taken apart.
Has anyone fitted this kit with success? Seeing as I've replaced the solenoid and it did not solve the issue, the end plug at the SR solenoid seems like the next logical part to replace.
At a glance, I'm going to say no and I've been watching since 2017.
Some of these require you to buy the installation kit which can be a couple of reamers to true the bore up.
I've been preaching to people for years that solenoids are only the messenger, they are told what to do and when input turbine speed and output shaft speed don't agree with the lookup table for the gear selected, the TCU throws a code related to the last command given which generally speaking, throws the solenoids under the bus even tho they are not at fault. Just like the article above says.
There is way more going on than people realize and internal leaks need verified as not being the cause.
If you have the time and patience to dig in, it could be worth while. Valve body assembly order and torque assembly as well as installation to the case can make or break your efforts. Torque and sequence matter.
Are there any A960 valve body threads/procedures/videos that you know of? I've come across other transmissions. I guess it would be pretty similar.
I did have trouble a year ago removing some bracket at the front which blocks the sump from being easily removed. Think it's got to do with the exhaust and it was rusted in. I'll have to sort this out first before opening up the transmission again.
Speaking to Driveline here in Australia, there were only 2 of these end plug kits sold to private customers ever. None were sold to shops. Another Sonnax reseller doesn't even have the part number in their system.
I'm wondering if the end plug can be removed without splitting the valve body apart. From what I can see in the installation instructions, my guess is that the retainer for the plug is only accessible from inside the valve body. I'm hoping to just install the 1 end plug at the SR solenoid.
Are there any A960 valve body threads/procedures/videos that you know of? I've come across other transmissions. I guess it would be pretty similar.
I did have trouble a year ago removing some bracket at the front which blocks the sump from being easily removed. Think it's got to do with the exhaust and it was rusted in. I'll have to sort this out first before opening up the transmission again.
Speaking to Driveline here in Australia, there were only 2 of these end plug kits sold to private customers ever. None were sold to shops. Another Sonnax reseller doesn't even have the part number in their system.
I'm wondering if the end plug can be removed without splitting the valve body apart. From what I can see in the installation instructions, my guess is that the retainer for the plug is only accessible from inside the valve body. I'm hoping to just install the 1 end plug at the SR solenoid.
The good news, if you drop the VB you get like 75% of the fluid out of transmission. Its honestly not bad at all. The worst part is when separating the VB make sure you don't drop or loose any of the check *****.
Make sure e everything is clean, no debris when putting it together and you should be fine. It would be temping to flush all the solenoids and with a small amount of compressed air it can be done.
You have a link to the instructions??
PS the A750 and A760 share parts with this even though the 750 is a 5spd. You likely noticed...
Search the web and my posts for the A760E/H 2010 Tundra new product release, there is a good pdf file with lots of details that likely apply to the A960E.
The last time, I couldn't get this exhaust bracket off. So it was a real challenge getting to the front 3 bolts on the transmission pan. Had soaked it in WD40 as well. About to buy a higher torque impact wrench.
The last time, I couldn't get this exhaust bracket off. So it was a real challenge getting to the front 3 bolts on the transmission pan. Had soaked it in WD40 as well. About to buy a higher torque impact wrench.
Thanks for that. Doesn't appear to be an Australian distributor for this kit.
But from the instructions, the end plug that I think is needed to fix the issue is on the lower valve body. I guess I should probably fit the whole kit since I've already gotten to that stage.
The transmission does not shift past 3rd at all now.
Previously, my workaround when it happens is to flick across to manual mode, shift down to 3rd then back up to 4th,then flick back to D and the transmission would be OK. And when it happened, the revs would increase noticeably.
Now, there is no jump in revs and the transmission just holds 3rd.
I have Techstream now. Any parameters I should check?
Are there any connections to check? ECU, loose wires?
Or replace the transmission? This will probably cost as much as the IS.
The transmission does not shift past 3rd at all now.
Previously, my workaround when it happens is to flick across to manual mode, shift down to 3rd then back up to 4th,then flick back to D and the transmission would be OK. And when it happened, the revs would increase noticeably.
Now, there is no jump in revs and the transmission just holds 3rd.
I have Techstream now. Any parameters I should check?
Are there any connections to check? ECU, loose wires?
Or replace the transmission? This will probably cost as much as the IS.
Did you make those repairs using the kit(s) or just keep driving it?
I suspect some of your solenoids are plugged and need flushed.
Did you make those repairs using the kit(s) or just keep driving it?
No, I didn't install the kits as I never got a reply from the transmission specialist in the area.
I suspect some of your solenoids are plugged and need flushed.
OK. I've been getting the same shift solenoid C code since day dot. Would exercising the solenoids through Techstream help or need to remove the solenoids?
No, I didn't install the kits as I never got a reply from the transmission specialist in the area.
OK. I've been getting the same shift solenoid C code since day dot. Would exercising the solenoids through Techstream help or need to remove the solenoids?
As I know it, they have cone filters but I've never actually held one so take that with a grain of salt.
There are one way and two way solenoids. The oneway ones, you can measure ohms and verify the open with 12v. If this were my problem, I would find a way to enable the valve and reverse flush it with Kerosene.
How creative are you?
Step one in my book is a simple flow test using a very large body industrial syringe flushing Kerosene through it while off and powered. To reverse flush, submerge solenoid and do some push pull on the syringe. Use a lean container and see if anything comes out.
As I know it, they have cone filters but I've never actually held one so take that with a grain of salt.
There are one way and two way solenoids. The oneway ones, you can measure ohms and verify the open with 12v. If this were my problem, I would find a way to enable the valve and reverse flush it with Kerosene.
How creative are you?
Step one in my book is a simple flow test using a very large body industrial syringe flushing Kerosene through it while off and powered. To reverse flush, submerge solenoid and do some push pull on the syringe. Use a lean container and see if anything comes out.
I have not done the above but the transmission seems to have gone back to its "normal" self - I can perform the workaround to get it to shift past 3rd again.
10-26-22, 07:30 PM
Transmission doesn't shift past 3rd, P0761, Sonnax end plug kit
