99 ml electrial problem
 

A 99 ML which twice would not turn over. Needed heavy charge to re start. Put new battery in and happened again. Other times it starts fine. Check to see everything is always shut off. Dealer has the car and can t find the problem. Sounds like it has a electrial draw only sometimes. What do you think??? System is charging and dealer cant find any draw while parked at dealer.

Try using the other key. Some have reported a problem with the radio key mechanism.

dealer had car all week, and of coarse it did not act up. Using it again until it doesn t start. Any things I can check or do????

Just to verify:
You are saying the battery is going dead and you need to jump it to get it going, OR is the starter cranking the engine and it refuses to start?

Gilly

We are seeing this often times when the starter fails. It will crank the engine over for less than a second and the starter will kick out.

It will not turn over. Even with a new battery, until it is jumped. Other times is starts fine. When you open the door the interior light is already so dim, I can tell it will not start.

I'd first recharge and test the battery again, and if that passes, then test the alternator output (amps and voltage).
If that tests OK, then they need to test the resting current draw. They may need to do this for an extended period of time using a good VOM with a "flight recorder" feature to see if it's spiking at times.

Gilly

Gilly, All this has been done up to a VOM with Flight Recorder, that I m not sure of. It was left with a MB dealer for days with them checking for a draw when parked. (nothing found). New battery and system is charging fine. The yellow BAS light in the dash comes on every once in a while and then resets soon after, could this be a problem? I ve had the truck back 3 days and it s working but I know one of these times it will not start (Hope it s in the driveway). Thanks, if you think of anything else I d appreciate it.

When the problem occurs (battery goes dead) you are saying it';; happen when the truck is parked over-night?
When it happens, is it usually in your garage and left unlocked, or is the truck locked when this happens?

Gilly

Outside. unlocked, at least one time, and once overnight and once only after being shut down for 10 mins... Has not happened again this week.:confused:

really sounds like a power supply or ground problem.
did you do a voltage drop test? you sure its a dead battery?

george

Yeah, there's nothing I can think of that would kill the battery in only 10 minutes. The largest consumer drain on the battery is the starter, takes a few hundred amps, at least initially, then maybe drops to closer to 100 amps, that may just kill it in 10 minutes, but, UH, I think you'd know it if that were the problem, eh?
The next in line would probably be the headlamps, they shouldn't cause a bateery to go dead in 10 minutes. With a brand-new battery as you say you have, you should safely be able to have those on for over 1/2 hour and still have reserve enough to start.
I would have to guess you have something intermittent going on with the battery itself or a bad battery connection, which suddenly gets better when the jumpers are installed over the clamps, something like that. Or maybe a bad ignition switch?
Sounds pretty weird.

Gilly

Sounds like it has a major electrical short. Does the cable "spark" when you touch it to the battery? I have heard that is one way to check to see if something is pulling a lot of power. I would guess that the spark should be very small- as the computer should be the only thing pulling energy with the car off and doors closed. On a older car (without computers) 1979-older? - there should be NO spark.
I have heard of a LOT of electrical problems with the ML320.
Some have resulted in fires that destroyed the entire car.

this is very dangerous. do not spark anything.
batteries go boom when you do this.
besides you can do a lot of damage to electrical
components.

george

True, but if the car does have a short and pulls a lot of power out when the cable touches the battery- there is actually no way to stop it- it will automatically spark. I should have actually said that this is a sign of a short, rather than "checking" it like that.