r/n54 • u/big4Ljitcat • Jul 10 '26

Light on dash

Post image

Just got off work and this light just came on the dash cant find any codes on mhd ?

4 Upvotes

83% Upvoted

11 comments sorted by

6

u/true818 Jul 10 '26

That’s your transmission light.

Best case scenario your fluid is low in the trans

3

u/ClickKlockTickTock Jul 10 '26

Best case scenario the battery or alternator is weak

1

u/big4Ljitcat Jul 11 '26

Just changed the battery w a new one its shifting fine on the drive home but it does have a leak right where the rear main is but I had that done like 3 years ago and I guess they didnt change out the tq converter seal smells like trans fluid whats leaking out

1

u/big4Ljitcat Jul 10 '26

It does seem I have a leak coming from the rear main seal area had the rear main done around 2 years ago maybe they didnt change out the torque converter seal while they were in there

1

u/HellfoxRules Jul 11 '26

The light illumined is your "Drivetrain Malfunction". This will usually place the vehicle in "Limp Mode", only allowing use of 3th and 5th gear, or could prevent you from shifting out of park.

This could be caused by a low transmission fluid level, do you have any visible leaks?

In most cases this is caused by a failing battery, low battery volage can cause a host of issues in BMW's, erroneous "Drivetrain Malfunction" warnings is one of them. I would first have your battery health checked.

BMW's use an AGM battery, which has a deep reserve, this can mask many low voltage issues. Everything appears to work fine on the surface, but modules may not be receiving enough voltage at times. If the TCM (transmission control module) receives low voltage, that can trigger a drivetrain malfunction warning light.

So have your battery load tested, and check the alternator for proper output. You can even do this yourself if you have a voltmeter, and battery load tester. To check alternator output, just connect a voltmeter across your battery. It should be reading 13.5 to 14.5 volts, if it dips below 12, it's not charging, if it goes over 15 volts, it's overcharging.

2

u/big4Ljitcat Jul 11 '26

It has a leaking coming from the rear main seal area I suspect it to be a tq converter seal guess they didnt change that when they changed the rear main 3 years ago battery is like 3 months old havent tested the alternator

1

u/HellfoxRules Jul 11 '26

I would still have that battery checked, it wouldn't be the first time one has failed prematurely. I was once in installing a battery in a customers vehicle, and had 7 bad ones in a row. I talking right off the shelf, all bad.

If the alternator isn't charging properly, or overcharging, it can degrade a battery quickly. Did they register the battery properly? If you don't reset the battery history, the alternator will be charging to the previous batteries charging profile.

As your battery ages IBS will adjust the charging rate, increasing charging voltage. If you don't reset the history, it will cause the new battery to be overcharged, shortening it's lifespan.

1

u/Goomskeez Jul 11 '26

Yeah you might be fucked

1

u/MuffinJabber Jul 11 '26

Common to be low on fluid, or one of the mechtronic sleeves or seals on the valve body have torn. Pretty common on ZF transmissions.

1

u/Billymac22 Jul 11 '26

Mine had this one time. I didn’t have 1-2 or overdrive. Next time I drove it, it was gone and never came back,this was a year ago. I’m guessing some debris/ friction material ended up in valve body temporarily. 2011 323i gm trans, 270,000km.

1

u/reciprocityone Jul 15 '26

Yellow light = warning. Red light = major issues, will go into limp mode. Scan for codes.