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HELP!! Red Alternator/Battery Warning Light

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Old May 7, 2014 | 03:43 PM
  #1  
GWagonStallion's Avatar
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2005 G55 AMG
Exclamation HELP!! Red Alternator/Battery Warning Light

Ok, so I'm driving down the highway yesterday, the low voltage electronic warning pops up to check the battery. About 10 minutes later it pops up again and then again and then eventually a red message appears telling me to go to a dealership.

Luckily I am about 10 minutes away from one and I get off the highway and get into city traffic and I notice my truck becomes sluggish when starting from a full stop. Now, I'm getting really worried and I turn off all electronics (but they still work, windows, radio etc). Just really slow from a complete stop.

I make it to the dealership and I rush off to a meeting.

Dealership calls me back to tell me it's $2,800. I ask them whats wrong. They say alternator. Yes, I drive a G55, but $2,800 for an alternator is ridiculous. Then I press for more answers, then they say I also need a new battery because the alternator ruined the battery. I asked them how that is possible when the problem only showed up today. They say that it could have been ongoing for a long time but the battery is dead. I told them I drive it everyday, I'm certain the problem just happened today.... Then they also tell me I need a new thermostat to regulate temperature. So that's why it costs so much.

Is this possible? What is going on here? Am I getting taken for a ride? Tow the car somewhere else?

Any thoughts/suggestions/feedback is sincerely appreciated.

Thanks!!!

Last edited by GWagonStallion; May 7, 2014 at 04:05 PM. Reason: Change Title
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Old May 8, 2014 | 12:08 AM
  #2  
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'99 and '05 E55 AMG
Tow it home or to an independent shop. Or be prepared to bend over and write a check for $2800.


Pull the alternator, take it to a local car part shop, have them test it. If bad, go to rockauto.com and purchase a rebuilt one ($114 + $54 core charge (refundable)). If not bad, more troubleshooting required. If new battery needed, purchase from Pelican Parts or Autohausaz ($100 to $350 depending on your battery). Or, better yet, purchase the alternator and battery, deliver them to the dealer, and tell them to install. Might, however, **** 'em off. If they refuse, be prepared to have your vehicle towed elsewhere (plan ahead!). A shop foreman should want to bring in some money versus suffering a total job loss and a never-to-return customer.


Thermostat costs $21 to $27 dollars plus shipping from Rockauto. Add coolant cost.


Windows and seats need to be reset and probable computer fault codes reset by the dealer or independent shop. But...much less than $2800.


Personally, I'd allow myself four to six hours to replace the above having never worked on a G55 AMG. That's allowing time to work around the supercharger. Then I'd take it to a dealer or independent shop as necessary to reset any fault codes.


I'm a Mercedes newbie but like to think I'm pretty darn good with mechanical and electrical issues. YMMV.


Best to you. Please update on what happens. Way too many posts on this forum where there is no resolution.
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Old May 15, 2014 | 02:15 PM
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2023 GLK250, 1987 560SL
The alternator is pretty quick and easy to replace. For someone experienced, it's about 1/2 hour on and off.

You can take it to a local alternator/starter repair shop and they should be able to fix it for about $100 to $200 depending on what it needs. A local independent mechanic should be able to do the job for under $300.
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