Transmission Failure: October 2015

Abby being towed from the EZ-Pass administration building parking lot.
Abby being towed from the EZ-Pass administration building parking lot 15 miles from home after a trip to Acadia National Park.


  • Pressure applied to gas pedal, engine revved, speed did not increase.
  • Shifting into various gears and stepping on the gas resulted in more engine revving, and at best, a few feet of movement.
  • During a test drive at the dealership, Abby threw a fault code that the technicians had never seen before and required a call to Mercedes headquarters (yup, Germany) for correct diagnosis.

Fault Codes:

  • There were fault codes, we just don’t remember them. We might have written them down somewhere. Time will only tell if we find them.

Problem: We initially hoped that a failed seal leading from the transmission case to the control board had caused a temporary short. Dave did some parking lot diagnosis, and thought that a failed seal might be causing the electrical connection to the computer to short out.  The connection was cleaned, Abby drove for about 30 feet and then died again.

We now know what an emergency, after-hours tow of an RV costs.

We also now know what a scheduled, normal business hours tow of an RV costs.

Solution 1: We had Abby towed to a friend’s nearby shop, where Dave hoped to work on it some more the next day.  The next thing to check was the transmission computer.  Dave followed the wiring back inside the cab and pulled the transmission computer.  As suspected, transmission fluid had wicked up the wires about 3 feet, and into the transmission computer. Dave carefully opened the computer case, cleaned and dried everything off, reassembled it, and reinstalled the computer.  Abby was placed in ‘Drive’ rolled about 30 feet, and quit again.  So much for that solution.

Solution 2: Abby was towed to Carman Dodge for professional diagnosis and repair. What was projected to take a week took a month. Initially, the error code that was being thrown was easy to diagnose.  The technician thought it was a bad shift solenoid on the valve body.  This was going to cost a fair chunk of change, but not the end of the world.  A new valve body was ordered and installed.  Abby started up and ran fine.  She made it about 3 miles into the mechanic’s test drive, and that’s when something gave up deep inside the transmission.

The error code Abby threw was something the dealership had never seen before and they had to call the mother-ship in Germany.  The new code meant ‘install a new transmission’.  Sigh.  The dealership called with the bad news.  After some pointed questions about having to pay for diagnosis time, a new valve body, AND now a new transmission, things were getting a bit testy. (It should be noted that it was not Jess conducting this interrogation, but Dave. The good cop was having a bad day.)  The service manager at Carman admitted that they misdiagnosed it, and they would eat the cost of the diagnosis and the valve body.  We have to give them a lot of credit.  In a day and age where dealerships are known for ripping people off, they did a stand up thing, and made it right.  We still weren’t happy about having to buy a new transmission at 65,000 miles, but Abby got one.

We purchased a Good Sam membership and towing coverage.

Repair Tips/Comments

  • Mercedes recommends servicing the transmission every 90,000 miles. Abby had 65,000 miles on her. Reports from the owner’s group is that more transmissions have failed in Sprinter based RVs than probably should.  RVs are often loaded to their maximum limits, and may also be tasked with towing, too. The recommendation is to service the transmission every 30,000 miles or so. Especially if the vehicle has been used to tow.
  • The repairs Dave attempted are not for the weekend mechanic who is used to changing a vehicle’s oil and maybe air filter. Only recommended for a seasoned mechanic. The transmission fix – just send to a professional.
  • Abby’s stay at the mechanic was not completely unfortunate. We were trying to sell the house at that time, so it was good she was parked somewhere safe during showings. Apparently a RV parked in your driveway is not a selling feature. The month long absence completely threw off our packing schedule and contributed to move out chaos.

7 thoughts on “Transmission Failure: October 2015”

  1. Sorry about all the trouble with Abby. Now you’ve got me thinking I should schedule a transmission maintenance before we head out to the TTT in August. And I can’t imagine what the towing must have cost. Hopefully all of that is behind you.


    1. The transmission was one the major thing we overlooked unfortunately. The manufacturer’s recommended interval was far too long. I think Mercedes has since decreased it to 75,000 miles and beefed up the transmission. The only thing that really saved us some money on the first tow was the fact we were only going a mile away.


  2. We will now be getting our RoadTrek’s transmission serviced before we head out west. Thanks for the heads-up, Jess!


    1. Since your Road trek weighs LOT less than our Winnebago,your transmission probably isn’t nearly as stressed. But, if your miles are creeping up there, it’s a good idea.


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