Alternator replaced now getting electrical problems!
Thread Starter
Junior Member
Joined: Jul 2013
Posts: 30
Likes: 0
From: Pottsville, PA
2010 C63 AMG. 2010 C300 Sport 4Matic. 2003 ML350
Alternator replaced now getting electrical problems!
Ok guys im new to this forum! So the other day I replaced my alternator on my 2003 ML350. Before I replaced it my Benz sat for about a year. Now since I replaced it, it wouldnt stay running. The battery was replaced and the battery light is lit. Today I had it running and was able to drive it back to my driveway. I let it sit and run for probably like 45mins. I would hold it at low rpms for awhile and then let it idle to try to clean it out. Now I was about to take it for a drive around the block and I gave it a few hard revs. After I did that my gauges would freeze and thrn drop all the way like I shut the vehicle off but it was still running. I obviously can figure out that something electrical somewhere is messed up but I dont know where. Unless I can figure out what it is, I will most likely take it to the Benz dealer. Any input or help is much appreciated! Thanks!
Senior Member
Joined: Mar 2002
Posts: 282
Likes: 5
From: Brisbane, Australia
2002 ML320, 2003 A160
Battery light means your alternator is not charging the battery. As this occurred immediately after your alternator replacement, you must check that the job was done properly. Connections OK? Did you DIY it? Replace it with what? New, remanufactured, 2nd-hand?
You can't drive it until you fix it. Well, you can, but you'll end up broken down on the road.
You can't drive it until you fix it. Well, you can, but you'll end up broken down on the road.
Thread Starter
Junior Member
Joined: Jul 2013
Posts: 30
Likes: 0
From: Pottsville, PA
2010 C63 AMG. 2010 C300 Sport 4Matic. 2003 ML350
Yea I did it myself. Bought the alternator at Advanced Auto, pretty sure it was just a brand new alternator. There are only 3 wires to connect. The battery wire and the other on that you put on with a nut on the back and the alternator voltage regulator plug. Now I did break that wire but I soldered it back together and plugged it in. Thats where I'm at.
Senior Member
Joined: Mar 2002
Posts: 282
Likes: 5
From: Brisbane, Australia
2002 ML320, 2003 A160
Because your alternator is bolted to a heavy object that vibrates at 10-50 Hz. The solder joint could easily be open circuit..
Last edited by DrX; Jul 7, 2013 at 04:34 AM.
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Senior Member
Joined: Mar 2002
Posts: 282
Likes: 5
From: Brisbane, Australia
2002 ML320, 2003 A160
From my interpretation of the diagram, the blue wire powers the battery light. Which means it's OK.
If you read your manual, the first thing to check is your poly-V belt. Is it routed properly and has the correct tension?
If you read your manual, the first thing to check is your poly-V belt. Is it routed properly and has the correct tension?
Senior Member
Joined: Mar 2002
Posts: 282
Likes: 5
From: Brisbane, Australia
2002 ML320, 2003 A160
I suggest you check the alternator ground cable and the battery negative cable. Both common points of corrosion, especially after long lay-up. Detach & clean both ends if necessary.
Thread Starter
Junior Member
Joined: Jul 2013
Posts: 30
Likes: 0
From: Pottsville, PA
2010 C63 AMG. 2010 C300 Sport 4Matic. 2003 ML350
Ok maybe ill give that a shot. Best idea I have for now. But the thing is before I replaced the bad alternator all my electrical was working fine.
