2019+ Sprinter Cruise Control Design Flaw

[Neon]

Originally Posted by rprochnow

Changing pressure on the seat can trigger the weight sensor, causing cruise control to be deactivated. I've seen this in our Sprinter chassis and other vehicles. All that's required to reactivate the cruise control has been to use the steering wheel controls.

The systems are programmed to ensure there is a driver in the seat while cruise control is engaged.

If this happens while just shifting around in the seat - the weight sensor may be too sensitive - but could still be as designed.

Perhaps the key to this may be to find and bypass the weight sensor if it is a real thing.

[rprochnow]

In this thread, two completely different cruise control problems are being discussed - which is somewhat confusing.

I started the thread describing the design flaw Mercedes has that causes cruise control and brake assist to be completed disabled - with no way for the driver to re-enable it until the vehicle drives directly behind another vehicle for several miles.

The other issue that's been introduced is temporarily deactivating the cruise control if the driver seat weight sensor sees a change in the driver's weight. This not a design flaw - but a safety feature present in vehicles from multiple manufacturers. There could be a problem with the driver's seat weight sensor if it is too sensitive and triggers when the driver shifts in the seat. Otherwise, the system is implemented as it should be - if the driver tries to leave the seat with cruise control activated - cruise control should be deactivated so the vehicle will start slowing down without driver intervention.

[LizofWI]

Rprochnow,

May I ask how you attempted to contact Mercedes? The dealer gave me the number 800-4MERCEDES, which I tried and it was a stream of SPAM ads, never did make it to any actual person. Now my dealer suggests googling "Mercedes Benz Corporate"-- which is crazy! A MB dealer doesn't know how to contact them.

I have contacted Pleasure-way, who made my camper, not heard back from them yet.

Liz

[rprochnow]

Sure - the more people complain, the better the chance this will get fixed...

Don't bother calling Mercedes USA Customer Care or Corporate - you get forwarded to a group that doesn't work for Mercedes and doesn't appear to be able to forward complaints back to anyone in Mercedes that could actually help fix the problem.

For now - don't drive more than 30-60 minutes in cruise control without a vehicle in front...

[Orlanvj]

Originally Posted by rprochnow

For those owners of Sprinter-based motorhomes, built on 2019 and later chassis, you should be aware of a major design flaw in the implementation of their adaptive cruise control.

If you drive for an extended period on cruise control on a road with light traffic, and the system doesn't see a vehicle in range of the radar in the front, after an undocumented extended period, the system will decide the system has failed, and will disable adaptive cruise control. This also disables active brake assist (emergency braking if an object is detected ahead).

When the adaptive cruise control is deactivated, you won't have any cruise control available - only manual driving using the accelerator pedal. The system will not fall back to standard cruise control (which doesn't use the sensors to maintain spacing).

Once the system is deactivated, it will not reactivate until the sensors are able to see a vehicle in front and you drive behind that vehicle for an unknown time while the sensors go through another calibration phase.

Our local Sprinter service has had our 2021 View several times, and recalibrated the sensors. On a June road trip, we lost cruise control for 5 days while driving in east New Mexico and west Texas. On our most recent road trip, we lost cruise control over 3 days while driving to/from Yellowstone National Park. In both cases, we were driving for an extended period without seeing any vehicles ahead. And the system only came back online when we were able to find a vehicle to drive behind until the cruise control reactivated.

According to Sprinter service, they checked with Mercedes engineering - and the system is operating as intended.

And, this would probably be OK for commercial Sprinter customers (the majority of Sprinter owners), when their Sprinter vehicles are driven almost entirely in urban areas which will always have other vehicles in front.

But for motorhomes travelling to state and national parks, especially off interstate highways, it is more likely there will be long periods without any vehicles in front of you.

I've tried to report this issue through Mercedes USA Customer Care - and their group (which is an outsourced phone support service) doesn't work for Mercedes, and doesn't have access to Mercedes corporate support or their engineering groups. And, Mercedes (in Germany) evidently won't talk with either customers owning Sprinter-based RVs or even Winnebago who builds a motorhome on the chassis.

So the likelihood of getting this design flaw fixed is very low.

What can you do about it.

First, if you have this problem, complain to your Sprinter service so Mercedes is hearing from their vehicle owners.

Second, if you are driving on a lightly travelled road under cruise control, every 30-60 minutes (period is unknown), try turning off cruise control briefly - and hopefully that will reset whatever timer the software is using to determine if there is a failure.

And, if you do lose cruise control, try to find a vehicle to drive behind for miles, until the system resets. Even if you have to slow down to increase the likelihood someone will pass you, who you can then follow, that may be better than running without cruise control or brake assist for hours or days...

This explains why my unit lost cruise control both times I entered Big Bend National Park. There is a long stretch of highway going into the park with out traffic and both times I entered the park the cruise control went out. I thought it might have something to do being in a remote area, satellites or cell service. But empty roads sounds like a possible reason.

[Sparky19053]

I've had the same issue with the CC going off line. Once in the snow and another in on SR95 in Utah. On Sprinter source it was described as Blind Eye. It happens when the eye mounted center of front window doesn't see other vehicles for an hour or more. When this happens the software decides there is a malfunction and for safety reasons takes the adaptive CC offline. It generally will reset overnight. I have not found a MB service bulletin on this issue.