2019 Sprinter - Cruise Control Failure

[crah]

I just checked the voltage and oddly it was at 13.01 volts. It's been sitting in my driveway since Monday without any charge source hooked up and the amp L Start disconnected. The chassis battery stated 12.5 volts at the one place readout. Seems my aux battery may be Ok either though I don't understand the higher voltage.

[Bobbit]

Thanks for the heads up on the battery but it doesn’t appear to be my problem as I just checked the voltage on it and it was 12V right on the dot.
I have an apt. Monday at a local Mercedes dealer.

Thanks

[Ontario Don]

Hi again - "12V right on the dot" is actually a bit low for a 12V lead acid battery. 12V is down around 50% state of charge - I believe these batteries should be 12.6V or above for a fully charged battery. I have no idea what type of continuous voltage the downstream highway tech stuff needs to work without interruption, but it is possible that your battery is not charged to max capacity.


Just info ... here's hoping the dealer fixes you up quickly.


Cheers,

[rprochnow]

Preliminary report from our Sprinter service is that there was a small rock embedded inside the bumper by the front radar sensor - and that could have been the cause of the cruise control failures that hit us during the last 5 days of our trip (before that, we didn't have any problems).

The technician is recalibrating the system (again) - and we'll pick it up tomorrow.

Though it will be several weeks before we'll get to take our next road trip and test the system again.

In order for a rock to get wedged in that area - it would have to be just the right size (not too small or not too big) and also bouncing up at just the right angle. While the odds seem pretty low for this to happen - since we didn't have any failures for most of our trip - and the system was offline for part of each of the last 5 days of the trip - it's very possible the rock was the cause of our problems...j

For anyone that is having cruise control problems - strongly recommend reporting this to your Sprinter service and have them inspect the system - and recalibrate, if necessary...

[rprochnow]

We have our 21D back - after Sprinter service finished recalibrating the system (again). Since we may not take a long road trip for a month or two, it will be a while before we can verify if the repairs fixed the problem.

It's possible a rock wedged between the bumper and the radar caused the failure.

However... There are two other potential causes:

First - if there is uneven weight distribution, causing the chassis to lean enough to cause the radar to get out of alignment - that could cause the cruise control system to shutdown. Evidently the cruise control failures are only happening to Sprinter-based RVs - and the increased RV weight could be causing the radar to fail.

Second - if the RV is driving for extended periods on lightly travelled roads - with no vehicle in front in your lane, the cruise control system has a timeout - and if it doesn't see any vehicles ahead for an extended period (an hour?), the system assumes there has been a malfunction, and disables cruise control and automatic brake assist. At some point, the system will try to recover - and requires driving behind another vehicle for long enough to re-calibrate the sensors.

If either of the above are causing the cruise control to fail, Winnebago should reach out to Mercedes and explore solutions. Driving without cruise control and/or automatic brake assist reduces the safety of driving Sprinter-based RVs - and a solution should be found.

[mricet1005]

Originally Posted by rprochnow

We have our 21D back - after Sprinter service finished recalibrating the system (again). Since we may not take a long road trip for a month or two, it will be a while before we can verify if the repairs fixed the problem.

It's possible a rock wedged between the bumper and the radar caused the failure.

However... There are two other potential causes:

First - if there is uneven weight distribution, causing the chassis to lean enough to cause the radar to get out of alignment - that could cause the cruise control system to shutdown. Evidently the cruise control failures are only happening to Sprinter-based RVs - and the increased RV weight could be causing the radar to fail.

Second - if the RV is driving for extended periods on lightly travelled roads - with no vehicle in front in your lane, the cruise control system has a timeout - and if it doesn't see any vehicles ahead for an extended period (an hour?), the system assumes there has been a malfunction, and disables cruise control and automatic brake assist. At some point, the system will try to recover - and requires driving behind another vehicle for long enough to re-calibrate the sensors.

If either of the above are causing the cruise control to fail, Winnebago should reach out to Mercedes and explore solutions. Driving without cruise control and/or automatic brake assist reduces the safety of driving Sprinter-based RVs - and a solution should be found.

I experienced your second case for the first time in May traveling from CO to Nebraska. I traveled for several hours without having another vehicle in front of me. It did come back on after a while of returning to traffic, but don’t remember how long it took.

[rprochnow]

We had the cruise control fail 3 times on our last trip. The first two times, it was on sparsely travelled 2 lane rural highways with the outside temp around 105. So we thought it might have been temperature causing the failure.

But the last time, outside temp was 85 - also on a sparsely travelled 2 lane highway.

So it seems more likely Mercedes has a design flaw based on the assumption Sprinter vehicles are always driving on roads with traffic ahead - and assumption that doesn't work for Sprinter-based RVs that could be driven for hours on backroads without traffic.

Has anyone else had their 2019 (or later) Sprinter cruise control cut out?

Was it on a lightly travelled road?

If this really is what's happening, hopefully Winnebago could work with Mercedes for a solution - such as lengthening or eliminating the timeout before a malfunction is assumed.

[crah]

I've had mine happen in the middle of San Diego on I5 rush hour traffic so not sure sparsely traveled roads narrows it down. It never came back on during my 6 hour drive back to Las Vegas. Before my radar replacement, I've had it happen so many times I didn't keep track. After thr radar replacement, I've had it happen 2 times. Once was on my way to Malibu (lots of traffic). And almost 2 weeks ago on a stretch of highway but othere vehicles were there. I couldn't recognize a pattern to narrow down the issue. I've had numerous incidence where the cruise automatically worked the next morning and also just a few hours later. Wished it was something simple someone can pinpoint. I've never had adaptive cruise issues on other vehicles and having adaptive cruise on large RVs is nothing new. Even the higher end big diesel pushers have had them for over 20 years. MB needs to step up on this.

[rprochnow]

Our Sprinter service mentioned the other potential cause could be uneven weight distribution that could cause the radar to be shifted enough that it is out of the calibrated zone.

Anyone else?