dlcoffin

Hi guys. 97 ls400. occasionally i get thrown ecu code p0770, and is evidenced by sometimes the torque converter stays locked and not disengaging until last minute when coming to a stop. if i wanted to, could i physically put a break in the solenoid control wiring, via a switch, so that lockup never engages? would that throw a code?

spuds

If the Guru's say its a tranny solenoid lots of threads on replacing it,doesnt seem hard or expensive.

dlcoffin

yeah, i know that. i've been reading everything i could find on this site regarding this. it is always going to be expensive, since i have no place to work on my car, and must go to a shop. so far, my question has not been answered. can i clip the wire that serves that solenoid, and if doing so, will it throw a code at me by the ecu when it attempts to lock up my torque converter via an electrically nonexistent solenoid? i'd be doing this via the wiring harness outside of the transmission, likely nearby the ecu inside the car.

Yamae

As far as I have experienced analysing different Aisin transmissions, the occasional P0770 was not always caused by the open solenoid. If it's open, the engine check light will stay ON. When was the last time you changed the ATF? Have you checked how clean it is? A badly clogged ATF often causes P0770.

dlcoffin

So, if the circuit is open, the code is generated, is what you seem to be saying. The trans is a replacement, used, for old bad transmission, done by the seller, done before i picked it up. I assume new trans fluid was used. it WAS overfilled, but i have remedied that by removing fluid down to where it should be.

Is there another way to disable torque converter lockup, then, that won't throw a code at me? is it disabled while in 3rd gear setting? its only popped up twice so far, and the second time, turned off the cel while on highway. I'm keeping an eye on it..

Yamae

The ECU is checking the solenoid in two ways. One is the continuity and the other is the movement in accordance with the discrepancy of the shaft rotations of in and out. Both the open solenoid and the discrepancy generate the code. Your idea sure causes the ECU to throw the code because of those 2.

dlcoffin

Understood. perfectly. thank you, yamae!

spuds

Yamae,can the wrong fluid cause his problem?

Yamae

The wrong fluid indirectly causes the problem because of clutch dusts and the debris disturb the movement of the solenoid.

The ATF Toyota T-IV is designed for Aisin's ATs which have the "Flex Rock-up Clutch" and it contains special additives such as over-based Ca-sulfonate and friction modifiers (FMs) to minimize problems such as a shudder, faster wear of clutches and others. Incorrect ATFs can't handle the "Flex Rock-up Clutch" well enough and there cause the clutch dusts and the ATF clogging. Solenoids have small clearances between each parts and when the ATF is badly clogged, the movement is disturbed. The attached PDF has an English part at the lower part of the top page and it would be useful for you to read. It would be best to read all but it's in Japanese and only the summary is translated. My limited English doesn't make it possible to translate well and fast.

spuds

Thank you so much.

Losiracer2

I went to a salvage yard and removed one from a car there, so far so good. You can try that as an alternative instead of spending $300 at a dealer