Benz W220 has no cruise control after ECU reset, how to reactivate?

Car model and year: Benz S-Class (W220)

Symptom:

After resetting the ECU, , wot key on `off etc,. Sparkling new performance,. throttle delay/lag is gone, trans shifts better. But have no cruise control.

Reasons why your cruise control isn’t working

Cruise control is a convenient feature, as it allows drivers to set a certain speed and allow their vehicle to continue moving at that speed, automatically applying more or less pressure on the gas pedal as needed to maintain the same speed. It’s not catastrophic if your cruise control feature isn’t working, but take a look at some of the reasons it could be and get it working again!

What’s wrong with my cruise control?

There are three main reasons why the cruise control might not be working. The first is that the brake pedal switch is going. When you apply the brakes while the cruise control is engaged, it automatically turns cruise control off. Your car may interpret the brake pedal going as you applying the brakes.

Another reason could be a blown fuse. This is a simple fix, as you just have to replace it. This can happen from time to time.

If the speed sensor or speedometer aren’t working, you may also notice the cruise control feature not working. These features are essential for setting cruise control, and without them, you won’t be able to apply the cruise control.

How to reactivate Benz W220 cruise control with Star Diagnostic System?

But I will say that correlation is not causality. Your ECU “reset” may have been followed by a failure in another system, and while they happened at the same time, they simply aren’t related.

If you really want to fix this, you need to hook it up to a Star Diagnostic System.

There are many, many “resets” or adjustments on the W220s – they are very complex computer-controlled vehicles. There is a huge amount of information available on-line. Some of the better sites include these two – https://w220.ee/

You can drive, and maintain, a W220 without owning an SDS (STAR Diagnostic System), but doing so is difficult, and can get very expensive very quickly. And the users of an SDS ask a lot of questions.

I need, and use, my STAR laptop more than my metric wrenches. With it, I can read every module, status, and sensor. It shows me troubleshooting steps and service procedures.

Without it, you are shooting in the dark, hoping that you hit something. When I say more information is needed, that’s because more information is needed. I’ve owned my S class for 8 years. I’ve been through lots of issues with it. I have probably seen something that can help you, but the car is too complex to say, oh, you have “X” so you need to do “Y”.

What is Star Diagnostic System?

Star Diagnostic System usually means C4 or C5, if you have a 2015 or newer (or plan to get one soon) then you need a newer unit like C4/C5.

Where to get SDconnect C4 / C5?

Here is the one I bought: a laptop, hard drive with software (SSD even though more expensive, it runs really fast), and a multiplexer.

Image 1: C5 bundle kit