How to Drain/Refill Automatic Transmission

Don't have to open the thermal valve on Tacomas. However if the idle is fluctuating because the jumper wire is still in, the fluid will warm up too fast & you'll end up draining out too much. End result is its under filled. I work at a dealer & have done hundreds of the fluid checks/adjustments. I've seen only 4 in the last 10 years that's actually properly filled. They're all usually low by 1/2 quart or more. It's a good idea to reset the learned memory after the fluid change to relearn the shifting time. Over time the ecu learns to shift slower because the fluid doesn't have the same viscosity. When you put in new fluid, it still shifts slow, & may slip & burn the friction material in the clutch packs.

 

Hold on. No need to get angry. Does your truck have the tow package?

One thing that explains underfilled transmissions is that the A750 transmission, as delivered by Aisin Warner to Toyota, comes pre-filled with a certain amount of fluid. The assembly line will add in enough fluid once the entire driveline is hooked up since you have to account for volume in the AT cooler lines.

Since the tow package adds an aux cooler, this increases the system capacity by a small amount. It would be NICE if Toyota got this part accounted for, but as we've seen even on the 2016s they are still struggling with this part.

Bear in mind that the entire system capacity is roughly 12 quarts for a 5Spd + Tow Package model. 192 quarts in total. Low by 16 ounces is 8%. Not perfect, but not a significant amount.

 

Why don't you use Techstream if you work at a dealership?

 

How do you plan on checking it if you're not doing the procedure?

 

Mehullica:

Thanks for your recent input in this transmission drain/fill thread. A dealer tech on another forum once posted the following in a Camry section. Said this would put transmission in learn mode. Would this also work on the A750E/A750F transmission?

Disconnect the battery ground and wait 10 seconds. Touch the ground to the positive and hold there for 10 seconds. Wait 5 minutes. Repeat the ground to positive for 10 seconds and then reconnect. This puts it into learn mode. Take it on an aggressive test drive. I suggest you do this AFTER replacement of the filter.

 

I do use techstream at the dealer. This procedure with the jumper wire is for non-Techstream users

 

OK.

Do you mind sharing where you find that the jumper wire needs to be removed once in AT TEMP check mode? The factory service manual doesn't mention it, and the various times I've gone into AT TEMP check mode, the temperature increase is sooooooo gradual and the RPMs maintain steady. I can't see how there would be enough going on with the engine that it would cause an incorrect AT fluid level.

 

Doesn't the Techstream just provide the trans temp and you still have to pull the overfill plug?

 

Answer to that is in Step 12 below - read the whole thing:

http://www.moranbahweather.com/toyota/lc_trj12/rm/rm1151e/m_40_0002.pdf

 

Thanks Lester. So that PDF is different from the other one that is floating around here. Any idea what that one is coming from?

 

Well I got the itch and re-checked the trans fluid level using the new PDF info. Disconnecting the jumper wire does change how the engine idles and you'll notice it when the ATF is trickling from the overflow port. That being said, the amount of fluid didn't vary at all. I went from a "optimally filled" trans, put 16oz into the fill hole, got into AT TEMP check mode, pulled the jumper wire, light came on, pulled the overflow plug and 16oz came out.

I'll use the new procedure from now on, but I am glad there wasn't a huge discrepancy in the amount of fluid drained between leaving the jumper wire in vs taking it out.

As for resetting the ECM after, I could see it being necessary if you went 60k on the original fluid and really abused the trans during that time. The viscosity will naturally change over time due to heat. If it happens with motor oil then it'll happen with trans fluid.

However in my case I am doing yearly drain/fill to the tune of 3.5 quarts as preventative maintenance. Since this is really overkill, the trans won't ever really notice a change in viscosity from a year of my soft driving. (but I like the idea of keeping the additives fresh)

Is the OP still around to update the first post in this thread? There are a few things that need to be noted:

1) The AT TEMP check light will come on for 2 seconds and then go off. It does not come on again for 2 seconds.

2) Add the step about pulling the jumper wire once you've verified you're in AT TEMP check mode.

 

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Correct - the A/T temp light only comes on for 2 secs when the system enters temp check mode. At that point the jumper wire/paper clip is to be removed.

When the lower level of the temp range has been reached, the A/T temp light will come on solid. This is when I remove the overfill plug.

Remove that plug whenever you like.

 

I didn't go through all of the thread, but has anyone tried used a ScanGuage to monitor AT temp??? might make this process so much easier for anyone who has one already like I do...

 

I did a drain and fill today on my transmission and followed this write up again. After a few times its fairly easy to go into temp mode.

I removed 3 quarts and then added 3.25 back in. Once I hit temp mode only about
1/16 of a quart drained from the check plug.

RJM

 

Sounds about right. You're all set and now you know that the level is correct. Drive with confidence.

 

Posting to help out anyone who may be in my shoes, i'm doing this today on a hot day for my area, around 90F. did a quick drive 1 mile down the road to pick up parts and back, drained my atf, pumped in the new fluid. When I go to put it into check mode the light just keeps flashing, I've waited almost 5 hours now and it's gone solid into check mode. i'm going to give it another hour to try and let it get below the temp and take it back up to solid, if it doesn't in an hour i'm just going to check the level then since it should be good to check when the light is solid. but beware of time best to do after sitting over night I would guess.

*Update
2 hours later the temp light was still solid when checking, never dipped lower than that I guess so I figured it was good and opened the overflow. one thing that was strange was that I had it down almost to what I would consider a "slow trickle" and I was about to cap it off, then the rpm dropped on my car and a big flow started back up... I let that flow flow until it came to a "small trickle?" and then I capped it. everything seems fine so far driving around the block, but I thought that was interesting.

 

And there you have it.

Elevate the front end...way up and you'll drain an extra qt. Refill accordingly - drive for a day - repeat the drain/refill. Do this every 25K-30K and you'll never have dirty fluid.

Yes - I know - some of you have gone 200K+ w/o changing fluid. And some people smoked until they were 90.

 

I just saw this after doing my first change yesterday. This is exactly what happened to me I was about to be down to a trickle and the engine rpm changed and a new stream of fluid started back up. I ordered 4 more quarts of fluid and am going to do another flush Thursday and will try this method.

 

This is why the correct procedure must be followed. Sudden RPM changes by even 50 rpms will pump more or less fluid causing the fluid to pour out the overflow tube

 

Thanks to the great information in this thread I was able to drain and fill the transmission fluid on my truck this past weekend. The fluid was ~17K miles old and was a bit darker compared to new fluid but nothing alarming. That gave me some peace of mind that the previous owner didn't abuse the rig.

Being paranoid to short out something on the OBDII connector I purchased a male OBDII connector and soldered a wire, between pins 4 and 13, to the rear side of its PCB. I think it cost me $6 (Amazon or eBay) and took about five minutes to get it soldered and screwed back together. Then I just plugged this dongle into the truck's OBDII connector.

A few things I noted:

1) Similar to one of the post from a couple pages back the A/T Temp light lit up for two seconds when I entered temperature check mode but it did not light up for two seconds when I put the rig in park.

2) I read the updated procedure about removing the OBDII jumper after exiting temperature check mode . . . after I was done completing the job. Hopefully enough fluid drained out. Next time I'll remove the jumper at the appropriate time.

3) It took about three minutes for the A/T Temp light to turn on after the truck was idling in temperature check mode. The outside temperature was ~70*F when I did this. An hour before I had driven the truck slowly up and down the street, since I had changed out some of the power steering fluid, so I'm sure this helped warm up the tranny fluid.

4) I drained about 2.7 quarts and pumped in 3.0 quarts. About 0.1 quarts came out of the check port when I decided the fluid was coming out at a "slow trickle."

Thanks,

Steve