Electrical Issues Please help!
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Junior Member
Joined: Mar 2017
Posts: 44
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2004 E55K
Electrical Issues Please help!
Hey everyone, I'm having electrical issues and I can't figure out what they are. I am currently rebuilding a neglected E55, and it worked fine until one night. It was the first night that I tried activating cruise control, and first night I went WOT. After both of those things, the red battery warning came on, and won't go away. I installed a new rear battery because I had it tested at AutoZone and they said it was bad. Tested it again after the new battery, and they said that the alternator and battery were good. However, the red light hasn't gone away, and the battery stays at around 13.4-13.5 Volts while idling and driving. The car has a good amount of electrical stuff that's going wrong, only after the red battery warning came on. When the headlights are turned off, the passenger side headlight will still blink, and sometimes when driving, the car will turn off all of the electronics. The back lighting on the dash will flicker, and so will the Brake light, as if the E-brake is down. Before the battery light came on, I was able to test the battery at AutoZone fine, but after it's come on, I took it to Advanced Auto, and the test won't complete. I think there might be a short somewhere, because all of the electronics will blink on and off randomly. The Aux Battery keeps the same amount of charge as the main battery when idling/driving and while turned off as the rear main battery. Any Ideas? This is driving me nuts!
Thread Starter
Junior Member
Joined: Mar 2017
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2004 E55K
I monitored the voltage both with the instrument cluster secret menu, and with a multimeter. At idle, it shows 13.4-13.5, after a drive, I turn it off and both batteries show 12.9 ish, so it leads me to believe that they are getting power from the alternator, maybe just not enough?
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Joined: Feb 2020
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From: Biloxi, Mississippi
Chevrolet Corvette Z06
Voltage definitely doesn't seem high enough. I don't know as much about AMG as I'm new to this world, but when my Audis aren't getting enough voltage, they do all kinds of weird stuff. As others have mentioned, check for water around any major harness connections.
Thread Starter
Junior Member
Joined: Mar 2017
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2004 E55K
Everything seems to be fine and I'm starting to think it's probably an alternator. The fact that neither Battery is receiving more than 13.5V when idling is worrying me. I just replaced the Voltage regulator on the Alternator, and it looks pretty new, but I guess the alternator has some issues. I am going to try that.
Newbie
Joined: Feb 2020
Posts: 10
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From: Biloxi, Mississippi
Chevrolet Corvette Z06
Everything seems to be fine and I'm starting to think it's probably an alternator. The fact that neither Battery is receiving more than 13.5V when idling is worrying me. I just replaced the Voltage regulator on the Alternator, and it looks pretty new, but I guess the alternator has some issues. I am going to try that.
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Joined: Dec 2019
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2008 R320 CDI 4MATIC
Everything seems to be fine and I'm starting to think it's probably an alternator. The fact that neither Battery is receiving more than 13.5V when idling is worrying me. I just replaced the Voltage regulator on the Alternator, and it looks pretty new, but I guess the alternator has some issues. I am going to try that.
It is well know the major issue with MB vehicles is the electrical system, and the battery is usually the issue. Batteries that do not have enough amperage, cause low voltage fault codes when the system is under peak loads. The low voltage confuses the control modules and may causes a host of problems, incorrect fault codes.
Get the highest amperage battery available for your vehicle.
Compare the original MB battery spec and get largest battery that is in the same size / fit to your vehicle During my search I have found that the ODYSSEY brand of battery have always been the largest in amperage, amp hours and weight{a fact they have more lead than all other batteries]. Yes they cost more than OEM MB batteries, in my opinion well worth it.
Review the data;
https://www.odysseybattery.com
Regards
Joseph~
Last edited by Joseph~; Feb 13, 2020 at 04:53 PM.
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Thread Starter
Junior Member
Joined: Mar 2017
Posts: 44
Likes: 3
2004 E55K
Update
It seems there is a parasitic draw somewhere. I went to check it this morning and the trunk battery was at 6.5V and the Aux battery was still fine at 12.5V. Can a parasitic draw like this, result in the alternator sending less than 14+V to the battery when the engine is turned on? Or is the alternator still bad and I should fix the parasitic draw AND replace the alternator?
It seems there is a parasitic draw somewhere. I went to check it this morning and the trunk battery was at 6.5V and the Aux battery was still fine at 12.5V. Can a parasitic draw like this, result in the alternator sending less than 14+V to the battery when the engine is turned on? Or is the alternator still bad and I should fix the parasitic draw AND replace the alternator?
Member
Joined: Jan 2017
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2006 E55 AMG
When you start 99.9% of most cars with a 12v electrical system, you will start off with around 14.1v to 14.2v, cold. As the car warms up, the voltage output at the alternator will drop to roughly 13.5v give or take. I think your batteries are fine and you need to focus on the parasitic draw. Sounds like you have a circuit that is "sticking" closed somewhere and drawing amperage. My current draw ended up being the alarm siren, which is not all that uncommon. However, that draw took a couple days to drain the battery down and that wouldn't cause all of the hectic stuff you got going on.
Bad grounds can cause all kinds of gremlins so I would start there first and then do a parasitic draw test.
Bad grounds can cause all kinds of gremlins so I would start there first and then do a parasitic draw test.
Thread Starter
Junior Member
Joined: Mar 2017
Posts: 44
Likes: 3
2004 E55K
When you start 99.9% of most cars with a 12v electrical system, you will start off with around 14.1v to 14.2v, cold. As the car warms up, the voltage output at the alternator will drop to roughly 13.5v give or take. I think your batteries are fine and you need to focus on the parasitic draw. Sounds like you have a circuit that is "sticking" closed somewhere and drawing amperage. My current draw ended up being the alarm siren, which is not all that uncommon. However, that draw took a couple days to drain the battery down and that wouldn't cause all of the hectic stuff you got going on.
Bad grounds can cause all kinds of gremlins so I would start there first and then do a parasitic draw test.
Bad grounds can cause all kinds of gremlins so I would start there first and then do a parasitic draw test.
Thread Starter
Junior Member
Joined: Mar 2017
Posts: 44
Likes: 3
2004 E55K
Update: The aftermarket Amp was constantly constantly drawing power, so I think the Remote wire in it is bad or something among those lines. Good news is, with that disconnected, I see normal Amp draw. I'll figure that out, and then figure out the other electrical stuff after.
Update 2: Just kidding, it was something on the car's main electronics. Time to go searching...
Update 2: Just kidding, it was something on the car's main electronics. Time to go searching...
Last edited by manon407; Feb 18, 2020 at 01:52 PM.
