Mercedes-Benz Metris Forum banner

1 - 4 of 4 Posts

·
Registered
Joined
·
226 Posts
Discussion Starter #1
Returning from a camping trip in Zion National Park, my van popped up "Power Steering Malfunction. See Owners Manual" on display between the Odo and Tach. It's a bear to drive without any power assist.

Ironically, almost exactly a year ago, as I was returning from a camping trip in Zion, within 50 miles of today's issue, I had the same thing happen. This was on highway US95 in Nevada northbound between Tonopah and Hawthorne. Out in the middle of nowhere. I had no real options but continue. Last year, I stopped at rest stop, and when I restarted the van, the power steering had returned. 10 minutes later, same thing. I stopped in Hawthorne for gas, and again, when the van was restarted, the power steering was back and continued doing is job for the 200 miles left to home.

I took the van into the dealer, and they replaced the entire steering rack assembly - the rack, the electric motor, and the control electronics.

Today, in the same stretch of US95, about 30 miles south of Hawthorne, same thing! I stopped at the exact same gas station in Hawthorne, and when I restarted, the power steering was back, and remained functional for the rest of the drive home.

With that long introduction, I have a suspicion/theory/guess as to a contributing factor. This stretch of road has grooves (rumble strips) cut into it along the center line, just as many roads do on their outer edge, to warn drivers that they are out of their lane. The grooves on this stretch are very aggressive. The speed limit is 75. It's two lanes, pretty straight, with a decent number of trucks and campers/RVs doing less than the speed limit. The grooves are so aggressive, that passing on that section definitely requires two hands on the wheel as the van's tires cross. The steering components take a beating as one front tire and then the other cross over a few seconds of very rough road at 60 to 80 miles per hour.

I'm wondering/guessing/theorizing/pulling things out of dark orifices that the pretty violent rapid "chatter" of one or the other of the front tires crossing over these things is causing the power steering controller to be confused into thinking there is some sort of failure in the power steering unit. Last year, I'm pretty sure the 'malfunction' message appeared while I was cruising along in my lane, but today, the message occurred as the left tire hit the rumble strip when I was pulling left to pass a semi.

It seems like too much of a coincidence to have this same reported malfunction a year apart, 15k miles later, on two different steering racks, on the same section of road under similar conditions.

I don't think I'm going to take it into the dealer this time. Last time, the replacement was $4100 list price. I'm not sure anything's actually broken other than confused firmware in the power steering controller and/or stability control and/or lane assist and/or all of the other computers monitoring the van's dynamics. I think some module is observing readings it wasn't programmed for and is shutting down the power steering with a false alarm fault.

Or, am I just kidding myself.
 

·
Registered
Joined
·
301 Posts
I think this has been reported by others where going over very rough road or vibration causing roadway patterns causes the steering system to shut down. It most likely is the computer thinking there's a problem from the rapid small movements continuously as its sensor system is extremely precise/sensitive.
 

·
Registered
Joined
·
3 Posts
It happened to us almost 2 years (January. 2018). We went over an expansion joint on a curving on ramp. That message popped up and the power assist shut off. We drove for another hour or so on the freeway, then stopped for gas, and everything cleared up. It has never returned. We took it to the dealer a couple days after it happened. They were unable to find anything either They did mention another customer who had the same problem after crossing a cattle grate. Sounds like the comment above is correct.
 
1 - 4 of 4 Posts
Top