P0770 Code - Now what?

[DoubleZero4x4]

OK, so I am driving around town today (it was 112 here in Phoenix) running errands and my 2000 4Runner SR5 thows a CEL. I look at the code expecting to see a P0171 again for a MAF or O2 sensor and its a P0770. Great, something is wrong with my transmission. Now that I have this code I don't really know where to go.

Anyone deal with this before?

I have a few ideas about what the problem could be, but what I dont know is whether this is something I can do (eg. dropping the pan and cleaning something, etc.). That is doable. Dropping the transmission is not really an option unless I send it to the shop.

Any advice would be appreciated.

[Seanz0rz]

See the description of this DTC in the FAQ thread post:

http://www.automotiveforums.com/vbulletin/showpost.php?p=4347425&postcount=28

P0770 Shift Solenoid E Malfunction

Solenoid E (SL) is the torque converter lock-up solenoid. If the torque converter is a little slow locking up, it will set this code. May only be a one-time thing owing to a small particle of something getting jammed in the solenoid. The code may disappear by itself.

If it doesn't right away, check out the color of your tranny fluid. If it is pretty much red or brown and smells ok, then flush the tranny and see if that gets rid of the code. If not, pull out some fluid and add a bottle of Seafoam Trans Tune and run it for 1 or 2k miles. Then flush the transmission again. Check if the code is gone.

If this problem persists, I've been told you'll have to replace the E-solenoid.

There is a Service Bulleting (EG006-00) issued for '00 Siennas on this problem. They get a new torque converter to fix the problem permanently.

The following discussion was submitted by csaxon:

The ECM uses signals from throttle position sensor, airflow meter and crankshaft position sensor to monitor engagement of Torque Converter Clutch (TCC).

The ECM compares engagement condition of TCC with lock-up schedule in memory to detect MECHANICAL trouble of lock-up solenoid, valve body and torque converter. A P0770 trouble code is set when TCC lock-up does not occur during appropriate speed, or lock-up does not release at appropriate speed.

Possible causes are:
* Solenoid is stuck open or closed.
* Valve body clogged or valve stuck.
* TCC malfunction.

There are simple electrical tests to check the solenoid and plunger but the transmission pan must be removed to gain access.

As Brian suggests, if you haven't had your system flushed or changed in awhile it may help but I'm not sure that's cheaper than actually removing the pan and checking the solenoid.

The Toyota service tech can check the system without pan removal with his analyzer.

found that with a quick google search. may shed some light on what is happening.

[MTL_4runner]

The iteresting part is that on 2002's that was a TSB item (but I think it was for a different reason).


Toyota issued a TSB (EG025-02) Title: M.I.L. "ON" DTC P0770 for all '02 4Runner and Tacoma V6 vehicles. The Introduction reads as follows:

Some owners of 2002 model year 4Runner vehicles and Tacoma trucks equiped with V6 engines and automatic transmissions may experience a M.I.L. "ON" condition with DTC P0770 (Shift Solenoid "E" Malfunction) stored when operated under the following conditions:
- Operation in ambient temperatures above 90* F
- When towing a trailer or carrying a heavy load
- When climbing a long uphill grade.
The ECM logic (SAE term: Powertrain Control Module/PCM) has been revised and the transmission valve body has been improved to prevent this condition from occuring.

The then go on to list the specific VINs that this applies to.

THIS IS A WARRANTY ITEM under the emissions and powertrain limitations.


Have you ever dropped the pan or done a tranny fluid flush on the vehicle?
Did you drop the pan and clean the filter screen at the same time?
What type of fluid did you use?
How long ago was it?

The troubleshooting for code P0770 from the FSM is:

Lock–up does not occur when driving in the lock–up range (normal driving at 80 km/h [50 mph]), or lock–up remains ON
in the lock–up OFF range. (2–trip detection logic)

1) Check shift solenoid valve SL (lockup solenoid) operation. (NG => step 2, OK => step 3)
2) Replace solenoid valve SL (lockup solenoid). (code returns => step 3)
3) Check valve body (NG => step 4, OK => step 5)
4) Repair or replace valve body. (code returns => step 5)
5) Replace torque converter

I wouldn't just assume that the lockup solenoid is bad (this is a pretty common mistake people make). The very first thing you should do before any of the tranny DTC troubleshooting is to thoroughly flush the system using the cooler lines and drop the tranny pan and filter screen since this code is often associated with debris floating throughout the transmission and wreaking havoc on seals etc, so flushing/cleaning it can be a crucial part of the solution.

Here's a great link if you need pics for removing the tranny pan, solenoids or valve body:
http://members.cox.net/mgriese5/Level10%20Pics1.html

[DoubleZero4x4]

Thank you for the responses. The last flush was December 2005 (about 25K ago). I checked the fluid last week, level is good, color is red with very little bown and no burnt smell, I have never dropped the pan or cleaned the screen. It's a street queen so there are no offroad trips on her and we dont tow anything. What I will do is get a flush done again and reset the ECU to see if that help the situation. The seafoam idea is also a good suggestion too, that will probably be step 2.

In looking at the TSB, it referenced ambient temps over 90. We certainly get that here. The asphalt temp on a sunny 112 degree day easily hits 170 degrees.

[MTL_4runner]

I checked the fluid last week, level is good, color is red with very little bown and no burnt smell, I have never dropped the pan or cleaned the screen.

The first part is a good sign and I wouldn't expect any burning since you do have a tranny cooler installed. :thumbup: Don't forget about dropping the pan, if you have never done it, you may be shocked at how dirty the pan and filter screen are. The pan should be dropped at every flush IMHO, but that's not always practical. I'd drop the pan before going in for the flush because if the filter screen is partially blocked to some extent, it may have blocked fluid flow and prevent particles from being expelled during the flush which would otherwise be removed.