PO773 shift solenoid “E” check engine light

Howdy y'all! I recently got my 2000 tacoma with 240k miles on it with the check engine light
PO773 shift solenoid “E”. My buddy who sold it to me said that AAMCO replaced the overdrive to fix that but it didn't clear the code. Truck took me to Austin and back with no problems. Any ideas what I should look into?

 

The computer knows if there is enough current going through the solenoid and will give a code and in this case its P0773 E shifting solenoid that controls the mechanical lockup within the torque converter. When you clear this code and it returns you can either replace the E solenoid and hope that the diagnostic trouble code doesn't return or you can take your truck to a transmission shop.

 

Is this something that needs taken care of urgently?

 

Sounds like you either have a bad solenoid or a wiring issue as that code sets when the ECM detects an open or short in the Shift solenoid. With that code present you will not have torque converter lockup, the trans should still shift ok but it may run hotter which isn't a good thing to do long term.

Writeup on your transmission here: https://www.tacomaworld.com/threads...sions-write-up-your-4-speed-automatic.325531/

@gearcruncher your thoughts?

 

Awesome thank you! I drove the truck to Austin and back, an hour or so each way and truck maintained a cool temperature. I'll be checking out that thread now!

 

Do you have a transmission temperature gauge?

 

Oh you're right, I wasn't thinking. It only tells me the engine temperature.

 

If AAmco was already in there making repairs , chances are its a wiring issue or lets at least hope its a wiring issue . Most transmission shops give at minimum 90 days warranty .

1- How long has it been since this repair at AAmco was made ?

2 Did your buddy take the truck back to the transmission shop to have it looked at when the problem didnt get repaired ?

3- Was there any warranty placed on the transmission when AAmco went in and fixed the overdrive problem ?

4- Do you have any paperwork showing the parts that were installed ?

As mentioned above , its not a good idea driving around without the converter clutch not functioning properly . Your going to go through a tank of gas very very quickly .

5 - When you pull the dipstick to inspect the transmission fluid level with the engine running in park , Hows the fluid level and what color is the fluid ?.

When the converter doesnt lock up , any fresh fluid that was recently put in the transmission is going to get very hot and possibly overheat . This means the re-agents in your transmission fluid are going to deplete far faster than they would if the converter is functioning properly . I am confused why a transmission shop would allow the truck to leave the shop without the converter clutch functioning

With this being said , there are 5 questions above we need you to answer in order to help you figure this out .

 

I have never been impressed with AAMCO and if I were in your case I would be looking for a transmission shop with the ATRA logo. No ATRA logo means no business from the likes of me. I already know how some of those AAMCO businesses run and I will stay far away from them.

 

The repairs were done about 2 months ago. He never took it back. I don't know of any warranties. The truck had poor maintenance records but I only paid $2600. The tranny fluid looks good, it's a nice red color. You're definitely right about the tank of gas thing. I was thinking I had a leaky fuel pump but it could be exactly what you're saying. I'm going to have to do more reading. This is all very helpful!

 

If you detect any slipping, late shifting, hard shifting I would address it.
On another note: Those solenoids are easy to replace but all too often people replace the solenoid and then the problem reappears. This I know happens with GM transmissions of the same era. Whether or not it applies to Toyota remains to be seen by me. You could buy one, drop the pan, replace it and never have another problem and attribute it to a little bit of luck.

Where some damage can occur is when the transmission fluid and filter do not get changed out regularly enough. Think about small particles suspended in the transmission fluid and they continuously travel throughout the transmission. Those small particles are probably 5-10 microns but after an extended amount of time as they travel those particles will wear out and damage the valves that are behind those shifting solenoids.
Preventive maintenance is a big thing.

 

These where my symptoms and how I fixed it...not sure if yours is the same but I’ll explain.

I notice my fault code p0773 would only kick on on long drive with a steady foot on the pedal cruising 65-75mph for about 45min-1hr, if i fluctuate my speed the code doesn’t come on. chased this issue for a while, flushed trans, no luck.
Finally dropped the pan and took off the 3 solenoid under there. Used my power probe and tested all 3 solenoid, all seemed to work fine and OHM the same but I noticed that the lock up solenoid seemed to get a lot hotter than the other, especially when activated for a long period of time. Then it dawned on me, if a solenoid is shorted I.e. getting hotter and hotter, it’ll deactivate once it get too hot. Hence the CEL when cruising for a while. Took a gamble and replaced that solenoid, issue never returned. FYI, a oem Toyota shift solenoid is $300+

 

Good information tsab916

Why in God;s creation would a lock up solenoid cost so much and this is where the aftermarket comes in. Its just a coil of wire a stamped casing and the business end has an O-ring.

Oh although I haven't researched it you should be able to test the resistance at the connector without dropping the pan.