Yellow Caution light - rear axle differential lock

[mcgm5]

Like I stated in the title.

I got a yellow caution light that stays on in the lower left hand corner of the gauge cluster stating :
"rear axle differential lock" -

And on the nav screen when I check the cars status it states :
"rear axle differential lock - stability limited during dynamic driving - drive moderately"

as well, the little traction light staying on (the light that normally flash's when you lose rear traction).

When I drive the car is sure does feel exactly what it states. that the rear diff is locked and both tires are being driven at once in all situations. no matter what setting are used or whether traction/stability control is on or off.

The car has 950 miles on it. And has yet to be driven "very" hard, and no launch's (LC not yet activated) or starting burnouts have been done.

The only thing that I had done different from the previous 949 miles (estimated) is that yesterday was the first day that I drove the car in the rain. As I left a 7-11 parking lot in the rain, the car was fine with no faults, and i got in front of traffic and moderately stepped on the gas to go, and the traction control light flashed and then never went off. The rear slipped slightly and that's when the yellow fault's went on. Never to shut off yet.

I though it might have been cause of the rain. but I started the car the next morning and the fault is still being shown.

any help ? fyi, their were no loud clunks or sensation of anything catastrophically breaking. The car was driven about 10 miles after the light went ON as i was leaving to get on an airplane and was not in the mood to deal with this issue at the moment.

If their is any other information that anyone would like , I will do my best to provide it. I would take photos but right now i'm on the other side of the country and my car is in NY.

btw, this is my first post. hello everyone. I got the car a couple months ago and have been reading the forum. Great source of info, so this is the first place i thought I would put a feeler out on to see if anyone has seen something similar on their car.

[thebishman]

Does it still come back on when you shut off the car and re-start?
Bish

[mcgm5]

Originally Posted by thebishman

Does it still come back on when you shut off the car and re-start?
Bish

yes

[volkswackin]

the rear diff has an electric motor which activates it...sounds like an issue with it. Id suggest a tow job to rule out damage to the diff.

[mcgm5]

Originally Posted by volkswackin

the rear diff has an electric motor which activates it...sounds like an issue with it. Id suggest a tow job to rule out damage to the diff.

thx so much for the post.

I understand that yellow means its driveable and red means get a tow. Also on the info (nav) screen it implied that driving the car was ok, but that dynamic driving would be limited. I'm sure you could understand that I'm scarred to death of a towtruck grabbing anything that is relatively low to the ground.

[mcgm5]

ok ,

so I came back from out of town after a week. started the car and the light is now gone. And car is back to normal. I tested all the settings and made sure the rearend would break traction without issue.

From what I can tell the issue is gone.

if anyone else goes through the same issue, please do post.

very happy the M5 is back to normal and driving great. Did not want to bring it to the dealer as leaving a car there is nervwracking in itself as their tech's are complete idiots IME. (at my closest dealer).

[mpgrant5]

I had the same problem had to have a control unit on the back axle replaced

[Tylerstar]

Had this happen to me tonight, hopefully it goes away in the morning. Not sure exactly what the problem could be.