laserblues2

Hello,

We have a 2002 ML500, when it went in for its service it came back and the speedo when stationary, flicks round to full speed. When you start moving the speedo comes back around and shows the correct speed.

I have no idea what this could be, Mercedes so far haven't been very helpful. Could this be a fuse / loose connection? They suggested replacing the dashboard at a cost higher than the value of the car!!

Help!!

Thanks,

Nick

DrX

The speedo signal comes from the traction control module (BAS/ESP) via a data network. If the speedo is faulty you can swap the cluster for a used one. Needs an MB computer (Star Diagnosis) to transfer the mileage across. If your dealer won't help install a used one, find an independent mechanic who will.

http://manual.startekinfo.com/manual...1/1_15/m13.jsp

laserblues2

Thanks for the reply Dr X

I've had the cluster / instruments / speedo (whatever you'd like to call it) replaced.

Now the battery light is on permanently, and also the lights don't work properly

Off - lights off and dashboard lights off
Auto - when its dark the lights are on but the dashboard isn't lit
Sidelights / main lights - lights on and dashboard lit

Only driven the car briefly but now the car won't start and needs to be jump started. It never had an issue before the speedo was replaced?

Arghhhh!!

On the bright side, when I'm stationary I won't get confused that I'm going flat out now

DrX

Battery light on means charging system fault. Usually voltage regulator or alternator. It's a critical system - you won't get far until you fix it. Has nothing to do with the instrument cluster - must be a coincidence. Unless your mechanic messed with it. Did he disconnect the battery?

laserblues2

Thanks for the quick reply

I don't know what the mechanic did...

He replaced the dashboard, I got it back with the battery light on & problems with the lights. Within 25 kms the thing won't start and needs to be jump started each time?

Just seems too much of a coincidence tho? I'm going to jump it tonight, then take off the negative battery lead and see if it keeps running. If so, the alternator is fine & there's either a battery issue or a short / drainage issue.

Any other suggestions?

DrX

Yeah, diagnose and fix either voltage regulator or alternator. It's a charging problem, not a battery or drainage problem. Poor connection from alternator to battery could cause it - this connection would be bypassed when you jumpstart it.

laserblues2

Oh ok, I figured that if it runs when jump started the alternator must be getting power to the car?

How would you suggest diagnosing it? It just seems so weird as we've never had an issue before - trying to get the original dash back too, just in case. Do alternators on these sometimes just die or is it more likely to be the connection?

Could there be an issue behind the instrument cluster? Could it have been connected incorrectly?

Thank you and sorry for all the questions!! I'm not much of a mechanic

DrX

Alternator or voltage regulator can fail at any time without warning, usually after they exceed a certain age. My VR died after 8 years. 2 years later alternator quit. Both times I was shown the battery light of death. The first time I didn't appreciate its urgency and kept driving, until I crawled to a halt and had to call a tow truck.

I suggest having it fixed professionally. Go straight to an MB dealer workshop or auto electrician. If you have a 2nd car and don't mind getting dirty removing your alternator, and have more time than money, then you can DIY.

laserblues2

I've been trying to get the garage who repaired it originally to come and sort it for me.

It just seems so weird to me that we change the dashboard, this light is on and it dies!!

Especially as the headlights / switches don't work normally either now!!

DrX

If it was the same garage both times, it's time to get a new one. How can they return the car with a dodgy speedo, or a battery light on? Did they pinch your speedo to fix someone else's?

The lights aren't working properly simply because the charging system went bad, so there's not enough voltage from the battery to run them all.

laserblues2

It failed the annual inspection, so went to this garage for a replacement speedo.

He replaced it, and as soon as he did the battery light came on. So he said it obviously needs a new battery / alternator. The light only came on when the dash was replaced (hence wondering if it was related) and then in the next approx 20/ 30kms the car died completely.

The headlights aren't working, the garage have been working to get the dash back (I never actually said they could part exchange it - my understanding was I was buying a new one)