2012 M3 Adding Avtive Cruise Control

[ColombianLuvsBMW]

Hi everyone! I was wondering if anyone in the community has added Active Cruise Control to a 2012 M3 with manual transmission. Car is stock so looking to make some modifications on the car.

Thank you in advance for any guidance as new to the forum.

[RocketyMan]

I think you mean "adaptive" cruise control.

Yes there are ways to add it. It required a front radar, a module, a different multifunction stalk switch, the wire harness, and then the coding.

[MilehighM3]

I briefly considered this years ago but traffic really isn’t an issue and I don’t drive my car often enough to make it worth the work. Provided the DSC is capable of accepting the retrofit, in theory it’s possible. You would need an acc sensor, mounting bracket, wiring, the DSC interface the E9x used called longitudinal dynamic management (LDM) and associated wiring, and some odds and ends. You could modify the front bumper grill to clear the sensor. After some coding you would need a dealer to calibrate the sensor and hope it’s successful. I’ve driven a lot of E series vehicles and the acc functions pretty well for what it is, but I don’t recall seeing this on a manual car before of any kind.

[Nickco43]

The M3 DSC pump does not support ACC. You would need to fit a regular E9x DSC.

[RocketyMan]

Originally Posted by Nickco43

The M3 DSC pump does not support ACC. You would need to fit a regular E9x DSC.

Yup...that makes sense as the non-M e9X have this ability in the US market using CC. I think there is a specific option code calling out the type of DSC.

[RocketyMan]

Yeah...so the DSC with "brake function." I wonder if this can be a simple coding option as looking through realoem doesn't specify clear enough.

The DSC does have different P/N, but the SZL seems to be the deciding factor for the S544 option for CC with brake option. This is how i'm interpreting it.

S540 Cruise Control
https://www.realoem.com/bmw/enUS/sho...diagId=61_3088

vs.

S544 Cruise Control With Brake Function
https://www.realoem.com/bmw/enUS/sho...diagId=61_2434

[Nickco43]

Originally Posted by RocketyMan

Yeah...so the DSC with "brake function." I wonder if this can be a simple coding option as looking through realoem doesn't specify clear enough.

The DSC does have different P/N, but the SZL seems to be the deciding factor for the S544 option for CC with brake option. This is how i'm interpreting it.

S540 Cruise Control
https://www.realoem.com/bmw/enUS/sho...diagId=61_3088

vs.

S544 Cruise Control With Brake Function
https://www.realoem.com/bmw/enUS/sho...diagId=61_2434

All 6CYL $544 DSC pumps and clusters also support ACC. The only part difference is the clock spring as you have listed there.

I personally wouldn't want to lose all of my M DSC benefits for the E9x long range only ACC. It cuts out at around 20 MPH and will not bring the car to a stop.

If I was going to try to do this, I would fit a E7x DSC ACC pump and first see if it would throw a fit in the car. If it doesn't then you could pretty easily add in the E7x LDM and ACC S+G sensor into the car as it is a self-contained system. That way the car will go down all the way to a stop without doing anything.

I tried fitting just the E7x ACC sensor and LDM to my E9x before, but the LDM threw a fit since it did not see the E7x DSC.