2007 Lexus LX470 P0776 & P2714 Transmission Shift Issues (2 Viewers)

[EAST TN 07LX470]

Looking for suggestions on where to start with troubleshooting. I have a 2007 Lexus LX470 with ~282,000 miles. Just today when merging onto the highway at ~75% throttle the transmission failed to shift from 3rd to 4th gear. The entire way home it would shift 1-3 and slip randomly in the lower gears. Got home and pulled P0776 and P2714 from the ECT in techstream. Codes are for pressure control solenoid B & D performance or stuck off. Tried clearing codes and disconnecting the battery for ~15 minutes. Same issue after driving again. I am getting ready to check AT fluid level. I did change the AT fluid with Toyota WS fluid ~5000 miles ago. I did a 14QT drain and fill method through the cooler line method that many people have claimed success with. I also meticulously leveled the car and leveled the fluid at the overflow at ~99F.

Any suggestions on where to start troubleshooting beyond checking the fluid level is much appreciated!

I should also note that this is not the original transmission. The PO had Mr. T put a new one in for the exact same issue at ~207,000 miles. Interesting that this is happening again...

 

[EAST TN 07LX470]

I just checked fluid level at 104F and had a good stream come out which tailed off to a trickle quickly. Fluid color and smell looked perfect.

 

[2001LC]

Check AT fluid temp #1 & #2.
Check that ECT (engine coolant temp) is making 184F or more.
Assuming ECT reaching op temp:
Send AT fluid sample to black stone. If reports metals:
Place inline AT fluid filter. The "Out" hard line to hose from AT to radiator is good spot. See if you get improvement.

 

[Vthelexus]

Interested to know the outcome. I am ready to replace trans fluid with Aisin WS on a 177,000 mile 2006 LX. This thread makes me rethink my decision.

 

[EAST TN 07LX470]

Yesterday I dropped the trans pan to inspect further. Fluid, pan and magnets were all spotless. I removed the mesh/screen filter and inspected it and the oring sealing it to the valve body. I was worried the oring was not sealing properly and causing loss of pump suction. All looked good there as well. I then followed the FSM troubleshooting steps for P0776 and P2714 which instructed me to remove and test each of the solenoids on the valve body. I was able to remove all but one without dropping the valve body or front drive shaft. For that unit I did testing and cleaning as good as I could while still in the valve body. On each one I measured coil resistance, all were in spec. I then proceeded to actuate each one with a 12V source. Note that the higher resistance solenoids can be tested with a direct 12V source. The lower resistance solenoids need a separate resistance in series, the FSM specs a 21W light bulb in series. All actuated fine, I also sprayed electronic parts cleaner through the orifices on each one as I was actuating them. I didn't see any gunk in any of them. I also checked the transmission external wiring harness connector on the drivers side. It was very crusty and almost appeared to have motor oil in the connector. I've read some of the horror stories of the A750F transmissions wicking ATF through the harness and causing all kinds of electrical issues. This substance was very brown and looked/smelled to be a mixture of motor oil and dielectric grease. I sprayed out and cleaned the connector with electronics parts cleaner. I also spot checked multiple other wiring harness connectors and did not see this same substance present, thoughts here?? I do have a pretty good leak on both cam seals. This car has also had bad VCG leaks in the past. Plan on addressing the cam seal leaks during the timing belt job.... not looking forward to pulling the cams for that. I then buttoned up the solenoids, filter, and transmission pan. Filled with 5 quarts of fresh Toyota WS ATF, and leveled the fluid at ~101F using the sensor #1 temperature readout in techstream. So far it seems to be acting fine, we drove ~80 miles yesterday at various speeds with no issues and no pending or active DTC's in techstream. Will do another ~80 miles or so today towing the boat. Fingers crossed that it behaves.

One other interesting item to note is that I occasionally have delayed drive engagement when shifting quickly from P to D. This does not occur in any other shifting pattern. I was able to get it to do this once yesterday even after the above steps were taken. This only happens ~1 in every 20-30 drive cycles.

The one item I was not able to check per the FSM is the transmission line pressure. I don't have a guage or line set to connect to the transmission in the manner it wanted.

I will keep this thread updated with how things hold up.

FSM troubleshooting for those two DTC's attached.

 

[EAST TN 07LX470]

Check AT fluid temp #1 & #2.
Check that ECT (engine coolant temp) is making 184F or more.
Assuming ECT reaching op temp:
Send AT fluid sample to black stone. If reports metals:
Place inline AT fluid filter. The "Out" hard line to hose from AT to radiator is good spot. See if you get improvement.
View attachment 3981007

Temps were fine when having the issue on both sensors #1 and #2. I never saw anything above 135F when driving close to the house and watching shifting in techstream. That was after ~20 minutes of driving. ECT was ~190-195F during testing. The fluid is new with no visible contaminants, magnets had zero build up on them as well. If the issue persists I may send a sample off. I don't see a need for a filter at this point as well. Even when I changed the fluid the first time the transmission only had ~75k miles on it and the fluid looked perfect with very minor build up on the magnets. I am curious, would an inline filter like that not add some flow restriction? See my overall thread reply for steps taken that seem to have things acting normally for now.

 

[2001LC]

The Magnefine ATF filter. Is designed, to allow proper (easy) flow. IIRC, its filter medium, filters to 50 mic, and its magnet, catches to under 3 microns.

A sample of your ATF, will let you know, if you'd gain and benefit, by filtering.

 

[EAST TN 07LX470]

Well we ended up driving ~40 miles unloaded and ~60 miles towing ~4000 lbs yesterday and everything worked great!