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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.
12-09-2023, 11:47 AM
