ISFLexy

I have a 2001 Lexus ES300, and recently got a check engine light on. I plugged my code ready and said "thermostat failure". I erased it and it came back, and this happened a few times. Now my transmission is acting up, when the car is cold, it starts fine, and once it shifts from 1st to 2nd its a hard shift, and eventually after driving for 10mins, it starts slipping, to the point where the engine revs and the car does not accelerate. Is it possible that the thermostat is responsible for all this? I read somewhere that it transmission relies on its temp to allow fluid through, etc. If anyone has experienced that, please share how you fixed it.

Thanks in advance!

sdls

While the transmission is dependent on maintaining fluid temperature in an optimal range, the problems you describe seem to go way above and beyond. Really sounds like an issue with the transmission itself.
Does the car take longer to go up to operating temperature? Does it overheat? Have you inspected the transmission's fluid condition?

ISFLexy

The fluid looks good and up to the mark. I have noticed that it does take a bit longer for the car to get to operating temps, and no overheating at all. I'm just wondering if it is linked, otherwise its a huge coincidence for me to get that check engine light for that and then have this issue a week later. The transmisson having jerky hard shifts and now slipping just came out of the blue, it was perfect before any of this, no signs of anything going wrong.

sdls

That's fascinating. Do you remember the DTC error code?
It makes sense to replace the thermostat anyway to see if the problem goes away. Is there an obstacle in the way of replacing the thermostat soon?

ISFLexy

I dont but I'll see if i can pull it up again, even though I erased it and it hasn't come back yet..

Oro

Jerky and hard shifts are most often related to a busted engine mount(s). Check all those. But not TC slipping; mounts or temps won't cause that.

I believe there is a computer control that eliminates OD until temps are warmed, but other than that, no PCU alteration of transmission shifting based on temps AFAIK.

ISFLexy

I actually got a code, even though there were no lights on the dash. P0770, which is the shift solenoid E malfunction. I erased the code, and after it drove perfectly fine, and code has not come back yet. It's as if nothing happened....perhaps a glitch?

Oro

A glitch, or a sign to do some maintenance.

I would run some seafoam or B-12 (use less of the latter - it's a little harsher, but it's also a lot cheaper so I prefer it) for a few days/hundred miles. Drain/fill the pan - make sure you are checking the fill level with the car running - add some Lubegard Red. Drain/fill your PS reservoir at the same time and put an ounce of the Lubegard in that.

The solvent will loosen varnish or things that may be interfering with a solenoid function. It will also condition seals and help soften harden ones (which can compromise solenoid function). The lubegard will do the same on an on-going basis but without the solvent. Last month I bought a Volvo (122k on it) from a seller who was certain it needed a new transmission, as he was told that by Tacoma Volvo, to the tune of $8,250. I replaced two motor mounts and did the above, and now the car shifts like new. They also told him it would cost $2,650 to replace the steering rack because of some feedback lash he was experiencing at full-lock and speed (think tight freeway on/off ramp). I did this same basic thing to the PS system and it works perfectly now. I have the dealer service records regarding this, so I know to the penny what they wanted for these and other unnecessary things; not just repeating a story I heard. I go into detail like this to demonstrate the procedure above is quite effective and sound, and also to demonstrate that there are mechanics who diagnose things and there are some who just wholesale replace parts and empty wallets. Find a good mechanic for when you really need one.

Oro

PS - I know the 4es platform decently and would know which mounts to go look at wrt shifting issues. That would be first and foremost the upper torque arm near the radiator cap, but to also examine all three lower mounts. On the 3es, there is a 4th mount running towards the rear of the car on the bottom that I understand is problematic.

Yesterday I worked on a 2006 4es with 98k on it. I noticed the right lower control arm bushing was cracking. On our 2002, it didn't look like that until about 250k, but also at the same age. So on things like mounts and bushings like that, it isn't just purely mileage before they fail - time takes a toll all on its own.

ISFLexy

Thanks for the input guys, so far she's still running great. I will look more into that seafoam stuff, but if it ends up being a very expensive fix, like new transmission, then I'm afraid I'd have to let her go as I got some crazy quotes of $3500-4000 to fix from tansmission specialists.