Greetings, fellow members!

I have a 98 ML320 w/c has just passed the 70,000 mile mark.
Would appreciate advice on what could possibly be causing the overhead trip computer not to function at random times. The little screen is completely blank. It has become hit or miss. My wife and I in fact have fun betting on whether the thing will come on or not every time we start the truck.

A by-product of this malfunction is that the SRS indicator on the dash does not light up with the rest of the idiot lights when in ignition mode and the Bose receiver stays on even after the vehicle is shut off

Yet at times, when we start the truck, everything comes on and works perfectly!

I checked the fuses and they're all fine. Could it be a faulty relay?

I'm hoping it's just a loose electrical connection but it sounds more that that.

Any advice would be much appreciated. Thanks in advance.


just call me RT

MB techs will just replace the entire trip computer =( Steve Cousin has them for sale, email him he has instructions as well.. good work steve

A tech would just replace the trip computer if it is faulty, I agree with that. There is nothing much you can do to them in the shop. An individual with time and patience could possibly make it work correctly again, if the individual has an electrical engineering degree or something like that.
It would be better to explore what is going on with these unrelated systems, especially if the symptoms all appear at once.
One guess would be an ignition switch not providing power to the circuits when it should.

Gilly

Gilly, tabo, thank you!

You're right, Gilly. The problem has got to be electrical in nature.

I failed to mention that the auto-dimmer feature of the rear view mirror also fails to work when this phenomenon happens. The little green light doesn't come on.

That makes 3 unrelated malfunctions caused by a bad ignition switch most probably?

As soon as I crank the ignition to position 2, and see that neither the trip computer, Airbag dash check light, and auto dimmer for the rear view mirror come on, I know they won't come on when I fire up the ML's engine.

And yet, the next morning I start the ML, they all light up as if nothing had happened.

This happens 50% of the time. Weird.....

Before I bring out the sledgehammer, I'll try observing and checking the connections first (under the fusebox, maybe) then have the ignition switch checked.

Cheers, gentlemen!

I've seen somewhere that power for the radio is somehow protected by two fuses, and if one of them blows, you get the symptom that the radio does not automatically turns of when you cut the ignition. (probably has something to do with the fact that the radio requires power even when the engine is cut, while the other parts on the same circuit don't).

You should check fuse F10, in the fuse box under the hood (should be a 10A fuse). Perhaps a bad contact, or a flakey fuse? That just may be your culprit ;-) .

Bram

Bram,

Thanks! I will give it a look.

Every little bit helps and I appreciate the advice you guys have offered.


Jim