Sudden change in trip computer mileage after power loss
 

Just recently I pulled out the fuse for the trip computer (while working on something else) on my 2001 ML320. I reinstalled the fuse and ever since then my trip computer indicates I'm getting 26 - 27 mpg on the highway.

I wish it was true, but I checked it manually. It's getting 23+- mpg on the highway, which is EXACTLY what the trip computer USED to say before I pulled the fuse.

The manual explains a process to callibrate the compass after the trip computer has lost power. I went through that, but it hasn't changed the mileage indication at all.

Anyone have any suggestions?

Gilly, is there another resetting procedure to try?

Thanks much.

Nope, just keep driving it, it'll correct itself.

Gilly

Well, how long to you think it should take?

I drive 90+- miles in my daily commute (all highway), and its been about 2 weeks since I popped and replaced the fuse.

So that's about 900 miles altogether. I've also reset the mileage a couple of times, but , so far it always climbs back to 26 - 27 mpg average.

Start the truck.
Reset the avg mpg reading using the reset button.
Don't move the truck, leave it idle. Your instantaneous mpg should read "0" mpg, as should your avg mpg. If this is not the case, the trip computer is malfunctioning.

Gilly

Hi Gilly,

I performed the test you suggested, and after a few seconds of sitting still the average mileage displayed 6.2 mpg! So I guess the computer is malfunctioning.

But, why did this start happening after removing and replacing the fuse?

That should be electrically equivalent to a fuse blowing out and being replaced. The engine was off when I did it. But that shouldn't matter anyway. I can't beleive Mercedes would design a system that can't tolerate a fuse being blown and replaced without causing permanent damage.

Does this make sense to you??

Thanks much.

Not sure if it makes any sense. I'm sure the test i gave you makes sense as far as the reading should stay at 0 mpg if the truck never moves.
Maybe it got some kind of power spike before the fuse blew.

Gilly