Transmission Idle Issue Code P0765

[JohnnyMc03]

Hello Everyone,

This is my first post on this forum; and I apologize for its length… The transmission
on my son’s 2001 ES300 stopped working. You could move the gear shift through all the gears (reverse thru 1^st) and nothing would happen. I had it towed back home and as the check engine light was on I hooked up my code reader and got back code P0765… which is a malfunction of the S4 Shift Solenoid. I opened it up by removing the transmission pan, fully excepting to see metal fragment or even chunks in the pan and around the value body... there were absolutely none.

So I took the next step and ordered a new S4 solenoid, filter and gasket kit and put it all back together, and filled with AT fluid A little skeptical that it couldn’t be that easy due to the fact that a few hours earlier this car wouldn’t even engage in gear before the repair… I turned the key the check engine light was off and I was able to put in reverse and back it out of the garage, all good signs. I took it for test drive around the neighborhood and all seemed fixed.

Later that evening I took it for a more stringent test drive and that’s when the check engine light came back on (I pulled the code after the test and it was once again a P0765). I notice however an interesting occurrence… when I sped up to say 60 MPH and 3,000 RPM (smoothly I might add) the transmission seemed to be working okay the Tach dropped all the way down to 1,000 RPM, when I let off of the accelerator. When I pressed on the gas again it needed to go back to 3,000 RPM before it seemed to engage the transmission again… much like a manual transmission if you stepped on the clutch peddle to disengage it coasting down a hill before reengaging it at the bottom.

This seems like it could be more of an electrical problem versus a mechanical problem and maybe one not inside the actual transmission… Does anyone have a clue what might be the problem?

Thank You in advance for any insight.

[lexis lexus]

I had a slightly different problem a while back w/ my '94. It wouldn't go into overdrive, and I would cruise at 60 mph running 3300 rpms. AFter I replaced the fluid and filter w/ no benefit. I took it to a transmission shop and they opined that it was probably electrical. Took it to the electric shop and they thought it "might" be a computer problem. I didn't want to spend a lot for a new one on a guess, so waited until I found a match at the bone yard (took about 8 mos of hunting...gotta find just the right one as there are several different computers for each year based on trim level, etc). Popped the computer in and got my overdrive back.

LL

[JohnnyMc03]

Thanks LL for the helpful insight.

I figured this was probably an on going issue that my son failed to let me know about, until the
S4 Solenoid went kaput, and he could no longer drive it. Now this computer is it the "main"
on board ECU ECM Computer that controls everything on the car, or is it one dedicated
to just the transmission and drive train operation? If it's dedicated to just the transmission,
where is it located?

Thanks again!

[lexis lexus]

I had an additional thought, based on your description of the trans reving up and then engaging. I'm not sure, but this may represent a bad torque converter, or not enough fluid, causing poor TC function.

Unless there was a radical redesign of the ES in the '00s, there's only one computer that controls engine and transmission (among other things), and it's probably located behind the glove box.

LL