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You should have rear battery voltage at the alternator output. They are connected through the 200A firewall fuse. If the fuse is bad, you won't have power at the alternator (engine not running).
So before starting the car I had O voltage at the alternator. I started the car and had about !! volts. Turned the car off and still had 11 Volts. Should i have had voltage all the time at the alternator or does the car go to sleep after sitting for a while and no voltage? If that makes sense.
There might be a bit of capacitance in the alternator. I would let it sit for 15-20 minutes and remeasure, but the 0 reading to start would indicate that your 200A fuse is blown. The alternator lead should always have battery voltage.
There might be a bit of capacitance in the alternator. I would let it sit for 15-20 minutes and remeasure, but the 0 reading to start would indicate that your 200A fuse is blown. The alternator lead should always have battery voltage.
Isn't 11 volts output from the alternator too low? Alternators should put out between 13.5 and 14.5 volts. Less than that normally indicates a problem in the charging system.
Isn't 11 volts output from the alternator too low? Alternators should put out between 13.5 and 14.5 volts. Less than that normally indicates a problem in the charging system.
Yes, but you might have to have battery voltage to power the field windings. I would worry about it after the fuse is replaced.
Pulled the alternator today as per a friend who is a mechanic. Removed the rear cover and sure enough it showed some melted plastic. Kicking myself that I didn't see it when installing new voltage regulator. Ordered new alternator. Fingers crossed.
It is possible that the alternator had a short to ground and blew the 200A fuse. Make sure that the output cable is not touching anything, then reattach battery cables and check for 12V at the cable. If you have voltage, fuse is fine, if you don't, fuse is probably bad.
djbadeaux:
you'll need 10mm sockets.. most everything is a 10mm nut..
for me, i folded the passenger carpet back, removed the styrofoam board, unbolted the metal plate, spent some time trying to wrestle it out of the restricted space it occupies, invented some new curse words, resisted the urge to fling metal plate across garage, unbolted woofer, more wrestling and cursing, went to bed, next afternoon resumed wrestling match, pried woofer up from bottom left edge (don't forget to unplug speaker wire on bottom right edge) got bottom left attachment point past folded carpet/foam padding, more wrestling and cursing bose and daimler, finally success as out it comes with no damage and only a few small tears in the carpet padding..
the cover on the round fuse box was missing on my car, so there were the fuses..
and attached is a picture..
cordially,
bill morrow
Thanks for thorough explanation, but I checked the fuses and both are good they have continuity and physically are good. What do I do next? The two batteries were replaced and they were load tested.
the battery red light error on the dashboard isn't going away. I changed both batteries and they tested good.
Did you do a battery reset? Scan tools with Mercedes-specific functions can do it, or you can take it to an MB dealer. On my car I used a Foxwell NT530.
I replaced the starter battery under the hood about 5 months ago. I just recently replaced the trunk battery and everything operated fine. The car has been sitting for about 3 weeks so I went to start it and got the "consumer electronics offline" dash light. It happens when I let the car sit for over 2 weeks. As the car was idling I noticed the red dash "take to workshop" light went on. The front battery was 12.9 volts and the rear was 12.8 although the car had been idling for about 10 minutes. It was charging at 14.1 V. I guess I'll run by the dealer and see what they say. The car is a 2004 SL 500 with about 9000 miles on the clock.
The starter battery is isolated so it won't discharge in a month, but the accessory battery will. When the accessory battery is low in charge the BCM sends a signal to disable the main consumers while the rear battery charges. It will take more than 10 minutes to charge, and 12.8 volts is an indication that it was being charged. Take it for a 30 minute spin and check again...! 9000 miles in 24 years is nothing, run that car more frequently ....! Not do not know why "take to workshop" came on, perhaps the BCM is malfunctioning or starting to burn..! The 30 minutes drive may uncover issues..!
The starter battery is isolated so it won't discharge in a month, but the accessory battery will. When the accessory battery is low in charge the BCM sends a signal to disable the main consumers while the rear battery charges. It will take more than 10 minutes to charge, and 12.8 volts is an indication that it was being charged. Take it for a 30 minute spin and check again...! 9000 miles in 24 years is nothing, run that car more frequently ....! Not do not know why "take to workshop" came on, perhaps the BCM is malfunctioning or starting to burn..! The 30 minutes drive may uncover issues..!
The Merc Dealer said it may have been the trunk battery, they are not sure. The code was cleared and everything is fine. I am going to swap batteries my with my E55 and see what happens. The battery I replaced was a Duracell maybe it's just a bad battery.
Hi,
I suggested it would be worth having fuses ready before starting the work, as it appeared from the symptoms that the !00 A fuse was gone.
I have just acquired some mega sized bolt-in fuses and I strongly suspect the the fuse size needed is the Midi-sized bolt-in rather than the Mega-sized bolt in.
The midi-sized bolt-in fuses appear to be more commonly used in automotive applications while the larger mega-sized bolt-ins are more common in large trucks and boats.
The required size can also be obtained on ebay at fairly low cost and the midi link fuses seem to generally have the following color code:
midi fuse typical value versus color of fuse body
30 A (Orange)
40 A (Green)
50 A (Red)
!00 A (Blue)
200 A (Violet)
Other color variants are also out there such as a black fuse body with the value printed on the body or stamped into the metal tag at one side of the body of the fuse.
Apologies for possible misleading info referring to 'mega' when what is almost certainly needed is 'midi'
I hope this further detail will prove to be helpful
Did you become certain whether it was the Midi or the Mega size which fitted in to the R230 fuse assembly?
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