Should I Replace Transfer Case for $3400?

[14thbmw]

Originally Posted by BMW_E53

So today I opened the TC actuator motor to see what the gear looked like before ordering parts and I found that its in relatively good condition. What are your guys' thoughts? I know I didn't take pictures along the gear itself because I didn't want to bombard you all with a ton of photos, but there wasn't any damage or much wear on the teeth like in the youtube videos from other DIYs.

Attached below are the pics of the black gear and the white gear as well. Looks like the white gear is starting to develop a crack so I was planning to purchase the whole Genuine BMW kit from ECS and replace the whole thing. Anybody know a reason why the three lights appeared and then went away?

There is enough black on your white gear to make me want to look at the gear it mates to - the one in the TC. Mine came out completely white after 165k miles.

The trifecta can come on for a sensor or a transient fault. I get them sometimes when a puddle or spot of ice makes one wheel slip, and it will reset after two minutes with the key out. Or there could be something wrong inside the tc.

[BMW_E53]

Originally Posted by 14thbmw

There is enough black on your white gear to make me want to look at the gear it mates to - the one in the TC. Mine came out completely white after 165k miles.

The trifecta can come on for a sensor or a transient fault. I get them sometimes when a puddle or spot of ice makes one wheel slip, and it will reset after two minutes with the key out. Or there could be something wrong inside the tc.

Here are some pictures of the inner gear on the transfer case itself. My car has just over 126,000 miles.

[14thbmw]

Originally Posted by BMW_E53

Here are some pictures of the inner gear on the transfer case itself. My car has just over 126,000 miles.

That looks pretty clean. Mine didn’t have any grease or dirt on the white gear/spline, and the TC side of yours looks clean too. Certainly no visible damage.

There are much better mechanics/diagnosticians on this forum than I; Pending their replies, since you have a new actuator coming I would put that in and call it good, unless/until the trifecta returns and stays on.

[wpoll]

Just FYI, this is what a stuffed gear looks like - you cannot see the wear if you look directly at the side profile of the gear (as in your pictures) - only when you view the gear from the edge.

The gear teeth should be flat in this view - like at the bottom of the gear. The wear is the curved hollow at the top.



(image from Johnnyvest at axleaddict)

I'm not saying you missed this (I'm sure you didn't) - I'm just adding this to the thread for future readers.

[BMW_E53]

Originally Posted by wpoll

Just FYI, this is what a stuffed gear looks like - you cannot see the wear if you look directly at the side profile of the gear (as in your pictures) - only when you view the gear from the edge.

The gear teeth should be flat in this view - like at the bottom of the gear. The wear is the curved hollow at the top.



(image from Johnnyvest at axleaddict)

I'm not saying you missed this (I'm sure you didn't) - I'm just adding this to the thread for future readers.

Yeah I was expecting to see my gear completely destroyed like in this picture and other pictures/videos from other affected cars, but when I took it out and cleaned the grease off, I was shocked to see my gear in good condition and with minimal wear so I'm confused why the computer tripped out like that.

[BMW_E53]

Originally Posted by 14thbmw

That looks pretty clean. Mine didn’t have any grease or dirt on the white gear/spline, and the TC side of yours looks clean too. Certainly no visible damage.

There are much better mechanics/diagnosticians on this forum than I; Pending their replies, since you have a new actuator coming I would put that in and call it good, unless/until the trifecta returns and stays on.

I appreciate your reply and help though! Hopefully after changing the gears and fresh new fluid will help solve the trifecta issue for another 120k miles.

And I see you have a 2018 M5 in your signature......Great choice my friend that car is a BEAST!!!

[cn90]

Original Poster,

The computer calculates wheel rotations, so if they do not match, then Trifecta light.

- Most of the time the plastic gear is stripped from repeated activation of the xDrive on slippery surfaces such as rain or snow.

- Since you live in California, the plastic gear does not have much of a work-out.

- A rare possibility is your electric motor is kaput. I guess you can apply some battery current to the motor to see if it runs. Anyway, the new actuator should answer the question.

[cn90]

Originally Posted by BMW_E53

...Anybody know a reason why the three lights appeared and then went away?

Classic reason is "low tire pressure".

Let's say the LF tire is 40 psi and the RF tire is 20 psi, you will get the Trifecta lights.
I learned it the hard way, don't ask LOL.

[Jeadiex5]

Originally Posted by sidneyj

Little off subject but jumped on here just to read this thread and I gotta say all of you that engage and provide this valuable information are just amazing!! Just wanted to say thanks to all of you that help us less knowledgeable people to save thousands of dollars!!

Amen brother! Yes...these forums are a huge help!!!! Has saved me thousands over the years with Volvos, Mercedes, BMW and Saabs I have owned. If you have a foreign car out of warranty, you'd be stupid to not get on a forum...unless you have money to burn..

Sent from my Moto G (5) Plus using Xoutpost.com mobile app

[BMW_E53]

Originally Posted by cn90

Original Poster,

The computer calculates wheel rotations, so if they do not match, then Trifecta light.

- Most of the time the plastic gear is stripped from repeated activation of the xDrive on slippery surfaces such as rain or snow.

- Since you live in California, the plastic gear does not have much of a work-out.

- A rare possibility is your electric motor is kaput. I guess you can apply some battery current to the motor to see if it runs. Anyway, the new actuator should answer the question.

Oh that makes a lot of sense now. And I wanted to test the motor but I was unsure which pins control/supply the power. Do you know which pins on the motor supply power so I can test it?