[Rekla]

To resolve these trifecta lights, here's what I did:

Diagnose - I used a Foxwell scanner. Un-resettable Error codes 5DF0 and 5DF1 indicate a bad DSC unit.

1. Remove negative battery terminal, Jack up the car.
2. remove left front wheel. I did remove the plastic engine belly pan so that in case of any spills it would end up on cardboard that I placed underneath.
3. Easiest access is through the left front wheel well after partial opening up the aft half of the left front wheel fender liner.
4. I ended up removing the coolant tank located above the DSC unit after syphoning it dry, held in place by 2 bolts on top. Catch the remaining coolant when disconnecting the hose, about 2.5 liters came out.
5. I siphoned out the brake fluid from the reservoir.
6. At the DSC unit Remove the square wiring connector - pull the tab on top all the way up, about 1-1.5 inches, the connector should then come loose on its own. Label the 6 tubes attached to the DSC. Not sure you can cross connect them, just in case. Then disconnect one tube a time using a size 11 wrench. Catch any drip with rags, avoid spills at all cost. Use brake cleaner to wipe off anything you think might have been exposed to brake fluid. I did not use a pedal depressor - I never touched the brake pedal during the DSC removal & install process prior to bleeding. after removal of the 6 tubes, the DSC unit is only secured by a single bolt. Remove bolt and wiggle the unit loose from its mounting supports (2 grommets).
7. With the DSC unit out of the car, remove its bracket (3 bolts).
8. Order the rebuild from Module Masters, sent them the DSC unit following their instructions. Turn around time for me was 9 calendar days. About $300 total with shipping charges.
9. Install following the reversed removal steps. Bolt on the bracket, install the DSC module in place, reconnect wiring connector and the 6 brake lines, install the coolant reservoir, add 2.5 liters BMW 50/50 coolant, top off brake fluid reservoir using DOT 4 LV brake fluid.
10. Reconnect battery. Start engine to bleed air out of cooling system. The reservoir has a bleeder valve. Since I measured the amount of coolant taken out, I made sure the same amount went in. In my case 2.5 liters. Do not touch the brake pedal yet.
11. Bleed the brakes, in sequence of furthest to nearest to the reservoir (right rear -> left rear -> right front -> left front). I followed the manual bleed process with a buddy of mine: one person in the car, one at the caliper. Build pressure on the pedal, hold depressed, open bleeder valve, pedal drops to the floor - hold in place - catch brake fluid, close bleeder valve, let go of brake pedal, repeat until air free and clear brake fluid comes out of the caliper. Repeat for each caliper in the sequence mentioned above. Keep the brake fluid reservoir topped off at all times!
12. The trifecta lights don't erase themselves. I have a Foxwell NT520 pro scanner and was able to clear the lights using this scanner. At first it couldn't communicate with the DSC unit, error codes 2DCC and 2DCD - the square wiring connector wasn't fully seated. That fixed this issue.
13. Test drive.

This is a very straight forward fix. It's not difficult and took about 2 hours to remove, 1 hour to install and another hour bleeding the coolant and brakes. I am comfortable working on my car, have a garage, do have a good set of tools, a quick jack, and Foxwell scanner. As for consumables You need about 1.5 liters of OEM coolant, 1.5 liters distilled water, 1 can of DOT4 LV brake fluid (or whatever you currently are using), brake cleaner, and shop rags. I called Module masters who assisted with diagnosing the no communication issue upon reinstalling the DSC - only after I tried reseating the wiring connector a few times myself. It's a bit tricky but eventually I got it seated and connected correctly.

The car can be driven with a bad DSC module. You will have brakes, just no dynamic stability control. In normal driving, not having DSC is not noticeable.

Hope this was helpful.