3rd Gen Automatic Transmission Fluid Level Check DIY

Toycoma2021 · Dec 29, 2024

Mike Z said: ↑

I plan on using the ScanGauge since I have it when I get a chance to actually check it. Need to confirm that the dealer actually gave me the correct fill plug o-ring as different Toyota dealers online sites gave different part numbers for that. Shifting from drive to neutral 13 times seems hard on the transmission especially if it does not go into check mode on the first try.
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Are you planning on not using the check mode? The check mode also controls the idle speed and thus to some degree the level.

Mike Z · Dec 29, 2024

By the time the trans temp meets the minimum temp the idle is about normal. The dealer uses techstream to get the temp and did not mention anything about check mode

Tacogent · Jan 6, 2025

Check out the video at post # 517 , by 'Brian2sun'.
No jumper wire needed.
I don't think Tacos 2021 and after can even use the 'jumper wire' method.

I've checked the upper and lower trans oil temps when in check mode via ODBII doggel and Torque Pro on my tablet and they were within +- 1*F of what they should be.

Mike Z · Jan 6, 2025

Looking again in the service manual I did find "Select the Active Test item: Connect the TC and TE1 / ON." in Techstream before reading the AFT temp with "Select the Data List menu: A/T Oil Temperature 1." I saw elsewhere that 800 rpm is the check fluid mode rpm and post #517 video shows the tachometer looking about 800 so I'll do the DND procedure to be safe.

Toycoma2021 · Jan 6, 2025

Mike Z said: ↑

Looking again in the service manual I did find "Select the Active Test item: Connect the TC and TE1 / ON." in Techstream before reading the AFT temp with "Select the Data List menu: A/T Oil Temperature 1." I saw elsewhere that 800 rpm is the check fluid mode rpm and post #517 video shows the tachometer looking about 800 so I'll do the DND procedure to be safe.
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Precisely, the idle speed is “controlled” in the level check mode. This is what many people are missing when they say they will just use some other device to check the temperature when checking the ATF fluid level. How much does the idle matter? Do not know, but that is what Toyota has developed and it seems easy enough to do with or without Techstream. I do have Techstream and I have never opened it up to use when checking my fluid - seems way too much trouble on getting the computer out and such.

GawainXR · Mar 4, 2025

Subbing

dougluvgold · Aug 3, 2025

The paper clip bridge in obd port isn't necessary , just the shift pattern will put it in check mode .

Taco Tyrant · Aug 28, 2025

rowsdower[OP] initial post: ↑

All the info in this DIY is already available on the forum, but scattered and mostly related to the 2nd Gen. I was able to get the procedure for my Turd Gen (2018 TRD Off Road 2x4) but it took me a while. I’m writing this down so it is all in one place for the next guy. My truck shifted normally but I did this check for peace of mind. I ended up being about 1/3qt low so I’m glad I did it.

First, understand how the transmission is set up. There is a fill plug, drain plug, and overflow plug. Fill and drain are self-explanatory. Behind the overflow plug is a tube sticking up into the transmission to a specific height. When there is extra fluid in the transmission, it flows into this overflow tube until the correct level is reached. If you are low on fluid, the level will be below the overflow tube (but you won’t know by how much). To get the proper fluid level, you need to overfill the transmission and then drain out the excess under the correct conditions. For the check to be accurate, the transmission needs to be in a narrow temperature window and the truck needs to be running.

The procedure is simple. Add a quart of fluid, put the truck into temperature check mode, get it up to temperature, and remove the overflow plug. When fluid stops coming out, you’re done. Parts of this process are very time-sensitive, so have all your tools laid out and make sure you fully understand the procedure before starting. If you are coming from a 2nd Gen truck, the procedure should be familiar but the specifics of getting into temp check mode are different.

Tools/supplies needed:

1 quart of ATF fluid -

$85 Toyota 00289-ATFWS Automatic Transmission Fluid, 192 Ounces, 6 Pack

Toyota 00289-ATFWS

1 crush washer -

$12 Toyota 35178-30010

Toyota 35178-30010

Drain pan

Fluid pump (if using Toyota fluid in quart container, get a pump that fits a gallon sized opening)

Paper clip

24mm socket

5mm hex socket

Torque wrenches that can do 29ft-lbs and 15ft-lbs (not critical IMO)

Stubby screwdriver (flathead or phillips will do)

1/16” drill bit

The Procedure:

1. The truck must be level to get an accurate check. Park on level ground or jack up as necessary to get it level before starting.

2. “Safety Third” is my usual motto, but not when I'm getting under a vehicle. Put on your parking brake and chock a wheel, as you will be leaving the truck running and shifting between P and D repeatedly, then getting under the truck. This could go bad quickly so make the truck immobile.

3. With the truck off and cool, get under it and remove the 24mm transmission fill plug. It is located on the passenger side of the transmission toward the back. The plug has “WS” on it. Using the fluid pump, add a quart of fluid through the fill hole. Replace the plug when done. The torque spec is 29 ft-lbs, but the plug has an o-ring on it. This o-ring does the sealing, so proper torque is not critical. I put mine in as the Germans do – guttentight.

Note that a 4x4 will look different than the pic below. peavey02 has added a photo of the fill plug on the 4x4 in this post.

4. Break loose the overflow plug with the 5mm hex socket. Just get it loose, then finger-tighten it. You will not have time later to fiddle with a socket so get it loose ahead of time so you can back it out by hand quickly. It should not be fully removed until later in the procedure, as there is additional fluid in the pan and all your extra fluid will come out and you will have to start over again.

5. Using a small screwdriver, push in the shaft on the transmission thermostat. Then, slide a 1/16” drill bit through the hole on the side of the housing to hold the shaft in. The thermostat is located toward the front of the transmission. Some say this step is not necessary, others say it is. It takes 15 seconds to do it. Supposedly this thermostat only exists on trucks with the tow package but I can not confirm that.

6. Put your drain pan under the overflow plug, and put your new crush washer on the ground near the pan. Maybe a rubber glove if you don’t want to get your hand oily. And put a rag there while you’re at it.

7. You are now done under the truck. Get your paperclip and jump the #4 and #13 pins on the OBD-II port. This port is under the dash near where you left knee would be when driving. If you have Techstream, it is also possible to get the truck into temp check mode using the software. I did not have access to Techstream when I did this so I used the paperclip method.

8. The truck uses the shift indicator to tell you when it is in temp check mode. The shift indicator is the “P”, “D”, etc in the bottom left corner of the screen between the tach and speedo:

First an explanation of how it works - when you first put it in temp check mode, the screen shows a D for two seconds, then it goes blank. When the truck gets to the correct minimum temperature, it will show a “D” on the screen regardless of whether the shifter is in D, N, or P. As it continues to warm up beyond the maximum temperature, the D will start to blink. If you are not done checking by the time it starts blinking, you need to shut off the truck and start over because it will be too hot. I timed this – it took 8 minutes for the D to appear with ambient temp of 75 degrees. 6 minutes later, the D had not started blinking yet but I turned the truck off as I was done and getting bored.

To get it into temp check mode, first start the truck. You will see a few error lights – this is because you jumped the OBD pins and is expected. Move the shifter from P to S, then back to P. Then move the shifter between N and D repeatedly for 6 seconds. Do not hesitate on N or D for more than 1.5 seconds, or the procedure won’t work. After 6 seconds, D will be displayed for 2 full seconds, then it will disappear and the screen will show nothing:

Move the shifter to park, take your foot off the brake, and pull the paperclip out of the OBD port. The error lights will go away. Wait for the D to reappear (approx. 8 minutes depending on ambient temp).

9. When the D is back on the dash, you only have a few minutes to work. Leave the truck running and get under the truck. Remove the overflow plug. You should see fluid come gushing out, then slow to a trickle. Replace the crush washer (remember to remove the old one) and put the plug back in. Torque is 15 ft-lbs but IMO it’s not critical since there is a crush washer - you will know when it is tight enough. If you only see a trickle when you remove the plug, rather than a big gush of fluid, you’re more than 1 quart low and need to go back to step 1 and add another quart (wait for the exhaust to cool off first).

10. Remove the drill bit from the trans thermostat. You will need to depress the shaft with the screwdriver again to get the bit out.

11. Turn the truck off.

That’s it! With a procedure this easy, it’s a wonder they ever bothered with dipsticks in the past.
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Thanks for the write up! What a pain in the ass though! I think a bunch of mechanics were fucking the head Toyota engineers wife based on the level of spite for mechanics in the design of the turd gen.

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