2.3L Transmission Solenoid Pack Replacement Guide (LJ4A-EL)

[Saint_]

One of my tranny solenoids was bad and I changed the whole solenoid pack in my 2.3L tranny. This thread is to describe the procedure to replace the solenoids.

Diagnosis:

If you receive one of the codes below, it is very likely that you have a bad solenoid:

P0740, P0745, P0750, P0755

To test the electrical integrity of the solenoids you have to access to the solenoid connector behind the rear intercooler. There are several connectors there, the one for tranny solenoids is the third one from the top. You can disconnect it without removing the battery though removing it will make it easier. Press the clip toward the engine and pull the connector. It is stiff so it might be hard disconnect for the first time. Measure the resistance between a solenoid terminal and a ground according to the table:



Terminal B is empty. Terminal F and D are the temperature sensor. Measure the resistance between F and D and compare the resistance with the defaults:



If tranny is cold you should read ambient temperature resistance. After a drive mine reads around 400 ohm. (means tranny runs around 80C).

If anything is out of spec, most likely that component is bad.

Parts:

The solenoids and temp sensor are sold as a pack. Mazda part # FX01-21-1D1A . It is a single piece from the connector to solenoids/temp sensor:



However you can still cut the bad solenoid and put a good one by splicing the wires. ATF is totally isolating electrically according to my test so you dont have to make an ATF proof isolation for spliced wires. My suggestion is to replace the whole pack if lockup solenoid or pressure control solenoid is bad and to try to find a good used one and replace only that for others. The reason will be clear later in this text.

The pack is $500 MSRP from Mazda. Online price is $365. I bought from here for $200+tax/shipping:

Transmission Parts Trans Online Automatic Transmission Parts Transmission Kits

I didnt see any difference between the old and new ones. Except the part number on the resistor is different. However they read the same resistance.

Replacement:

Replacement procedure is as follows:

1. Disconnect and remove the battery.
2. Disconnect solenoid pack connector and route it back up to tranny side. It enters to the tranny on the front left top corner. You may have to remove the air filter box. I have a short ram intake so over there is pretty roomy.
3. Remove the driver side splash shield.
4. Drain ATF by removing the drain plug.
5. Remove the tranny pan. Now you should be able to see the valve body and 3 solenoids:



Ignore the black rubber hose, it is not related to this job.

The arrangement of solenoids is as follows:



The schematic on the right is from the top of the valve body. As seen TCC lockup and pressure control solenoids are on the top, which require valve body removal. I had problems after I removed the valve body that is why I suggest just to replace the individual parts for Shift A, B, overrunning solenoids and temperature sensor.

6. Before removing the valve body you have to remove the solenoid connection to the tranny. Remove the steel clip by pulling it out. Then tap the white/yellow connector into the tranny (visible in the picture above). I stick a rod (screwdriver or wrench extension) from the wheel well and tap it in with the hammer. It is very tight and it is not possible to push by hand.

7. Remove the valve body. To do so remove the bolts shown by black dots on the above picture. 3 of them (A) are longer.

8. Valve body is not light and with the jack stands you dont have too much space. Besides, you will get extra ATF splashing. So take your time. I left two bolts on the front and back then hold it in place and remove them. Be very careful not to damage it. You will get extra ATF and a spring falling when it is removed.

Here is the tricky part. There is paper gasket exposed when valve body is removed. The gasket is very fragile. Think of a piece of paper soaked in to ATF for 10+ years. And it is heated up to 80C (180F) for 1000s of hours. Can you imagine how fragile it is? I damaged the gasket prolly during first installation and had gear slipping when it is hot. It was a nightmare and I had to do the job again after 3 days. When I removed the valve body I realized paper gasket is damaged:

Before 1st install:



Before 2nd install:



Fortunately the missing pieces dont look so crucial. I put gray gasket maker instead of the missing pieces.

9. Replace the solenoid pack (I almost forgot ). This is trivial. You should put ATF around the O-rings of the new solenoids. Since everything is floating in ATF, you cannot avoid ATF running on the O-rings anyway. Be careful with the metal washers sandwiched between the bolts and pressure control solenoid. Just check how it was before removing it.

This is how the tranny looks with valve body removed:



The falling spring goes to the hole on the top left corner in the first picture.

10. Route the solenoid connector through the hole and install back the valve body. You have to adjust the manual valve to the connecting rod (easy). It is the sliding rod above the filter. As I said before be careful with the paper gasket. Bolts should be torqued in a circular pattern.

Torque spec for valve body bolts: 6.9-8.8 N.m

11. Dont install A bolts and remove and clean the filter. Clean the magnet as well. My filter was totally clogged in the small port. That was most probably the reason for slipping gears.



Though, that gasket piece should have been sitting there for 5 years at least. Spray brake parts cleaner to clean up the filter.

12. Tap back the solenoid connector. I used a rod and a hammer to tap it up. It is doable after valve body is installed. Put the steel clip back.

13. Install the pan and drain plug. I used gray gasket maker which is the most suitable.

Torque spec for the pan bolts: 6.9-8.8 N.m

Torque spec for the drain plug: 40-53 N.m


14. Re-route the solenoid wires and plug the connector back.

15. Gray gasket maker cures in 24hrs. Best is to wait overnight before putting back ATF. I put 5.5 quarts of ATF in total. Use dexron 6 from walmart. Remember Dex6 is one of the most wanted items in walmart, at least thats what I observed. So stock it up before the job. I had to eventually put dex3 which I can tell the difference. I can see foaming on the dipstick with dexron3 after the first start (valve body needs to be filled) that I didnt observe with dex6.

16. Install the remaining parts: battery, splash shield etc.

Thanks for reading

[bigb]

Hey Saint_

Just in case you (or anyone reading this guide) ever needs to replace that paper gasket, the Mazda part is (Part # temporarily removed since I might have gotten it wrong. Give me a day or 2 to get the right one)

It is in section 1925 of the Mazda part catalog

[Saint_]

Originally Posted by bigb

Hey Saint_

Just in case you (or anyone reading this guide) ever needs to replace that paper gasket, the Mazda part is FX01-21-817

It is in section 1925 of the Mazda part catalog (D-Code 21-817)

Changing that means rebuilding the valve body (it covers the whole body). That has a lot of tricks, its better to get a professionally rebuild one.

T2T thanks. I wrote what I just learned, Yel-low writes what he knows

[bigb]

Actually, it's not as bad to take apart as you might think. the only hard part is putting the ball bearings in the right place, but if you look at the way it's moulded it becomes evident where they go, and they should just stay there. even the paper gasket has cutouts where the bearings roll.

I wouldn't touch it if its working for now, but if you ever have to go in there in future, I'd still change out the gasket

I have some pics here when I took mine apart. This is one of my spare valve bodies that I had opened up when I installed the shift kit. I hope this helps anyone that attempts this part of the job. I have more pics if someone is in a jam and needs em. you can PM me.


This is the bottom part. You can see the bitch in all her glory. note mine cracked in the exact same place as yours

here is the top part I pulled off with the ball bearings in place


And finally re-assembled after a quick dip in the part washer. squeaky clean. I never did replace the gasket on this one, though its a 2 min job now that she's all clean.

[Saint_]

Those check balls are exactly what I meant. If you ever loose where they go I couldnt find any document showing the inside. Then you are in big trouble. In that manner the photo you posted is very valuable. There are 5 of them that I can see, is that right? The other thing is during reassembly they put some kind of ATF soluble resin to keep the balls in place. The bolts are at the bottom so you have to flip the body to tighten them. I dont know where to get that resin..

[bigb]

Saint_

For the check valves, there is no compound you really need to hold them in place. I did not use anything special for this rebuild, just a 10mm socket.

If you put them in the top half, you can hold it together with your hands and then flip it upside down to fit in the bolts. If you put it in the bottom half (with the paper gasket) look closely. the holes where the check valves cover are mitered at a slight angle to provide a better surface area for the ball bearing to seal against. This holds them in place quite nicely. Remember you dont really care where they go, as long as they are in the right channel. Once you bolt it on and fire up the engine, the fluid will go where it wants to and push everything into place after a few shifts. I wasn't worried.

ps. If you look at pic 3 near the bottom there is actually 3 sections of the valve body. section 1 is the smallest (not shown in the pics), section 2 which you see in pic 2, and then the bottom section with the paper gasket. Sections 1 and 2 come off together.

If someone is willing to host a rather large pdf or zip file, I can attach all my images. it's basically a valve body writeup

[bigb]

Here are the pics of the top most plate.

Here is the bottom side of the top plate


Here is the top of plate #2 where plate #1 mounts. Note the additional check valves.


hehe now that I look at it maybe it's not so trivial. If you attempt this and screw it up don't blame me hahaha

Just make sure to use a digital camera every step of the way and take LOTS of pictures. Mark everything!

[Crossoldier]

Hi: I'm only want to know where is available the paper valve gasket or the number part I can't find it.

Thanks

[Crossoldier]

Hi I install the valve body with out gasket and works excellent!!

[imaddicted2u]

This is the right gasket FX01-19-803 Available from Mazda dealer.