05 4.8is Transmission GA6HP26Z Snap-On Code 4F8A

PUREVIL · #1 12-20-2011, 12:50 AM

Hey All -

As the title would indicate, I've got a transmission fault. I've scoured these and other forums but not found my exact symptoms. Any help would be greatly appreciated.

The X5 is a 2005 E53 4.8is, Trans model GA6HP26Z. Just under 60k on the odometer.

The problem originally occurred when starting off from a red light. I was facing up-hill and making a left hand turn through the intersection. There was a car coming at me and I needed to give a little extra on the go pedal. I launched away as normal but then, sssslllliiiiipppp.... I let off the throttle just in time to hear a chime and see the notorious TRANS.FAILSAFE MODE appear on the display. The transmission completed the shift and I drove away as normal. The display cleared itself after shutting the car down and restarting.

I researched the issue and decided to start by verifying the oil level. (not leaking)
I drained the transmission into a clear jug. The oil was not black, did not show any signs of "glitter" and did not smell burnt.
I refilled the trans (following the instructions found on this forum) and according to my measurements it took a full liter more to fill it than what I was able to collect while draining it.

The X drove perfectly after that for 4 days. Then, exactly the same thing happened under the same circumstances. Facing uphill, turning left, hard acceleration. It got me thinking - so I tried again. This time from a dead stop on level ground, wheels pointed straight ahead. Pedal to the floor = same results.

The only computer I have access to is a Snap-On. The code registered is:
4F8A Ratio Monitoring gear shift 4-5. I am unsure why it would be monitoring the 4-5 shift because it works beautifully there. The problem I have is either 1-2 or 2-3 ***EDIT: Problem is 4th to 5th gear, upshift only***.

I'm planning to pull the pan check the valve body next.

Should be noted that this thing downshifts like a dream, does not suffer the known lurch issue, and if driven "conservatively" one would not know that this problem exists. But you can bet your ass I didn't go for the big V8 so I could drive around conservatively...

Anyone have any input?

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SlickGT1 · #2 12-20-2011, 12:03 PM

I don't have anything to suggest other than checking your Valve body. But want to subscribe to see other suggestions. I have the same car.

So only left turn? Could it be something related to the x-drive?

TwinsPoppa · #3 12-20-2011, 12:41 PM

I just started experiencing this same thing recently. 2004 4.8is a little over 80K miles on her.

The only difference is I don't get the TRANS FAILSAFE MODE message.

It doesn't do it very often and only does it if aggressively accelerating (straight or turning).

I'm currently researching this but here are some documents for some good reading.

I currently don't have my GT1 so I can't scan for codes at the moment.

Maybe its torque converter/TQ lock-up related. I'll update here if I find anything or have ideas.

There are tons of threads to go through.

EDIT: Here are some download links for you.
transfund1.pdf - SlingFile - Free File Hosting & Online Storage
tranfund2.pdf - SlingFile - Free File Hosting & Online Storage

TwinsPoppa · #4 12-20-2011, 02:41 PM

Here are two more docs on Electronic Transmission Control.

electran1.pdf - SlingFile - Free File Hosting & Online Storage

electran2.pdf - SlingFile - Free File Hosting & Online Storage

SlickGT1 · #5 12-20-2011, 02:52 PM

Read that whole PDF. Wow, I am even more confused. I read your entire 51 pages of the GT1 thread yesterday as well. I now have a perpetual headache. Thank you very much.

Yea it would be great if it was the TC, but I fear that will all of these 6 speeds failing, that the problem might be bigger.

TwinsPoppa · #6 12-20-2011, 03:01 PM

Quote:

Originally Posted by SlickGT1

Read that whole PDF. Wow, I am even more confused. I read your entire 51 pages of the GT1 thread yesterday as well. I now have a perpetual headache. Thank you very much.

Yea it would be great if it was the TC, but I fear that will all of these 6 speeds failing, that the problem might be bigger.

Yeah, there are so many variables but that's part of the challenge.

We have to live with it because we already know pretty much what most dealers' solution will be - new transmission.

I'm going to see what codes I get in mine - if any. Better to replace a torque converter than the tranny.

If I re-read that thread, my head would have exploded!

SlickGT1 · #7 12-20-2011, 03:05 PM

Yea dealer would replace it 100% and charge you more than the car is worth.

Find out what codes you get. Curious what this is all about.

I can't wait to scan my car. Curious to see what I get from my trans as well. I have that lurch currently. Seems to be a non issue if I drive aggressively though, and sort of stops lurching for a while.

My last weak ass automatic experience, 10 years ago, Ford, once it started showing signs of slipping, it's days were numbered.

TwinsPoppa · #8 12-20-2011, 03:09 PM

Purevil,

Does your tranny hesitate for a 1-2 seconds when you put it in reverse before it engages?

I'm curious because mine does hesitate.

PUREVIL · #9 12-20-2011, 08:26 PM

Quote:

Originally Posted by TwinsPoppa

Purevil,

Does your tranny hesitate for a 1-2 seconds when you put it in reverse before it engages?

I'm curious because mine does hesitate.

TwinsPoppa -
Nope. Other than the slip under hard accelleration I currently have ZERO issues with the trans.
Thanks for the links to the literature. I've been spending my time searching for info on the issue but everything I find seems to be coupled with some other ailment (like yours).

I don't know if I'm just catching this so early on that I haven't had time to wreck anything else or what.

The closest thing I could find to my issue was on a ZF 5 speed. It wound up being an axial needle bearing failure that wiped out an internal seal. It was allowing a pressure drop under load, causing slipping of the effected clutch.

I've got an appointment with my local indy on Thursday. Fingers crossed... Hoping for a sticky valve or solenoid. I just can't see rubuilding a trans with 60k on it. I won't consider replacing the trans. If it has to come out, it's getting rebuilt and stuffed right back in. That'll teach it!

PUREVIL · #10 12-20-2011, 08:35 PM

Quote:

Originally Posted by SlickGT1

So only left turn? Could it be something related to the x-drive?

The left turn is no longer a factor. Will do it in a straight line also. It just happened to be an uphill left turn the first two times it occurred.
I was suspicious of low oil at first, thinking that with the car facing uphill, the oil would run to the back of the pan. The hard left turn could then slosh the oil to the back right corner of the pan leaving something in the front left of the trans starving for oil...

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