'99 ES300 Transmission Prob - Code P0770

[Pete Zaria]

Hi everyone, very clean and organized forum you have here! I'll do my best to keep it that way.

Background:
I have a '99 Lexus ES300 with a 1MZFE VVT-I engine, the same as the '99 Camry V6. I have approximately 73,000 miles on the car.

I have not done very many modifications. A custom air intake, Brembo Big Brake kit, one-inch-drop lowering springs, 17" rims & Falken tires, and took off the Lexus badges.

I'm an avid do-it-your-self'er and weekend mechanic. I've taken good care of this car since I've owned it (since about 40k miles), having done oil changes every 3500 miles and following the other maintenance procedures as laid out in the shop & Chilton's manuals at recommended intervals. I'm 3k behind on changing the spark plugs though.

I drained and filled the transmission a little under 1,000 miles ago using Valvoline MaxLife (DEXIII/TypeT).
There were no metal shavings in the drain plug or fluid that I could see. The fluid was a little dirty, but was a healthy color and did not smell funny.

The Problem:
I've been getting the check engine light occasionally. It happened twice before I drained/filled the fluid, but is more frequent now.
My OBD2 reader says it's code P0770, which traces to the Torque Converter Lockup Solenoid if my research is correct.

The car is shifting smoothly through all gears, including overdrive. I have not seen or experienced any lockup problems.

I clear the code, and it comes back - Usually a few days later, once or twice it's come back within a few hours. It's happened maybe 8 or 9 times total.

My Questions:
Before I freak out and take it to a transmission shop, is there anything I can do myself?

Should I drain/fill the transmission several times in an attempt to flush it?

I've read on some forums that this vehicle does not have a filter in the transmission pan. I have not dropped the pan before. If there is a filter in there, I'll be glad to replace it.

THANKS FOR YOUR TIME!

Peace,
Pete Zaria.

[Pete Zaria]

Update:

I had a shop powerflush the transmission and change the filter. The code stayed off for a day - came back on driving home today. However, this time, no check engine light - just the "VSC" and "VSC Off" lights.

Either that solenoid has got to be bad, or my ECU just hates me and is throwing bullcrap codes.

Any ideas, anyone?

Peace,
Pete Zaria.