Hi,

Long time reader... new poster

I have a 2002 ML320 that has just developed a new problem and I'm wondering if someone has had a similar problem and can provide some insight.

The other night after picking up a friend... the SRS light came on... My Radio started flickering on and off and the same with my headlights.. I began to lose power drastically and about 5 minutes later I find myself on the side of the road and the car wont start. After multiple attempts.. even the interior lights disappear. I immediately assumed there has to be an issue with the alternator.. and a gentleman offers to give me a jump. The car starts.. but immediately dies again 2-3 minutes after he disconnects.

The next day I replace the battery with a new one I bought from walmart. Voila.. it works.. I drive the car around for a bit.. (10-15 miles)... park it at home.. come our 2 hours.. later.. drive another 2-3 miles.. BOOM. SAME exact thing.

I'm thinking.. this has to be a faulty battery or something. I get another one.. voila.. it's fine again. Drive around for about 20 minutes and boom.. dead again. Battery is dead as a door knob again.

Should the car battery DRAIN in 20-30 minutes? I spoke to a repair technician on the phone and he mentioned that even if the alternator were bad.. the car wouldn't drain that quickly.

On a unrelated note (I hope).. the car has been misfiring on cylinder 1 (Code: P0301) for about a month. I replaced the spark plugs immediately after it started, but it's still misfiring..


I hope someone can provide some type of help here.

Thanks in advance.

Also... I forgot to mention. I did lose the cd changer in the car. It's stopped working a while ago.. and the sound system has been cutting out off and on for weeks.. like it would play for 30 seconds.. then there would be a 5 second pause... then play again. Almost like it's shorting.. Do you think this could be related? Would a short cause the battery to drain quicker?

Your first assumption was correct!
The charging system is the problem. The "technician" that said the car couldn't kill the battery that quickly is mistaken.
That model & most other new cars can consume as much & more power than the alternator can generate.

You need 120A and more output from the alternator to keep up with the demand.

Have you checked with your MB dealer to see if that ML falls into the voltage regulator recall that affects 350,000 2002-2005 vehicles?

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator