New owner of an e53 4.8is with issues :)

[Peezen]

Hi there,

I recently bought a 2004 4.8is to by winter ride and it came with a host of issues, most that I knew about, and it was priced accordingly. I have a 91 850i and my wife has an Z3 and an LR3 for work, and I do all repairs myself, so you get the picture lol!

I have done a tonne of reading on the various codes I’m getting but nothing like a clear picture, and form plan of attack, so I figured I’d join you all in here and ask for some help/advice

Here are the symptoms I have so far:

- Front axle drops fast when SAV is off
- trifecta lights all on (4x4, brake, ABS) all yellow, and tire pressure light as well
- self levelling suspension inactive message on display (will not go into extended or access via the switch)
- when driving, it will drop itself into a fail safe setting and there is next to no power. There are no visual warnings, I notice when it happens when I step on the gas.

I have a Schwaben/Foxwell bmw code reader, a Creader, and INPA. Here are the pertinent codes:

Transmission:

-51AF: signal from transfer case faulty
-4F7A: No message from transfer case

ABS:

-5E24: front left wheel speed sensor
-5F39: transfer case

VTG:

-54C6: oil wear
-55C8: no message from DSC
-55C9: no message from DSC

There was also a steering angle code 9 on the LWS ECU. Not sure if it’s related.

Things I have done/PO did:

The PO replaced the transfer case actuator with a brand new one, a cheap Amazon one from what I can tell. I removed it and has a look and it does look brand new. I had a look at the TC module and it looks brand new, safe under the back seat. I have replaced the TC oil with factory fluid. I have ordered a new front left wheel speed sensor, and a new front air spring.

I ran some live actions on the ABS and could hear the pump work, and I ran a test in the TC actuator and could hear it functioning as well.

From the looks of it the transfer case is not communication with the ABS module or the transmission, this could be the reason that limp mode is being activated. Conversely, the TC seems to be having an issue getting info from the DSC, so perhaps that is shutting it down, which in turn affects communication back to the ABS module and the transmission. Could a faulty wheel speed sensor cause all of that?

Seems like a circle here but Inhave to start somewhere. Anyone had this group of codes before? The trifecta seems to point to either the ABS or the transfer case from what I have read and I have codes for both!

Any help or direction would be greatly appreciated