SL/R129: 1994 sl500 charging system
Thread Starter
Junior Member
Joined: Apr 2017
Posts: 52
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Sl500
1994 sl500 charging system
Hello,I have a SL500 I was driving it home and went to pass a truck going 50 mph.I dropped shifter into 2nd like I always do and as it took off I put it up into drive I was doing about 80 and as I backed off accelerator the car shut off a solid red light came on as it stalled on me.I pulled over and restarted the car and it ran fine..But I noticed the battery light is on now.The car never got hot or drove funny after it shut off.I got home and shut it off and waited 5 min restarted car it started fine but battery light is still on.Anyone have any ideas what is wrong??
Thanks in advance..
Thanks in advance..
Thread Starter
Junior Member
Joined: Apr 2017
Posts: 52
Likes: 0
Sl500
Charging system
I checked fuse and all fuses under hood non are blown ..unless there is one somewhere else.
I checked volts at battery when car running its only at 11 v so alternator isn't putting out.
I checked volts at battery when car running its only at 11 v so alternator isn't putting out.
Member
Joined: Jul 2008
Posts: 213
Likes: 31
From: SW Florida
1995 SL500 - 2017 AMG GLC 43
You can easily pull your voltage regulator to see if it failed.
Or just buy a rebuilt regulator.
Your choice. I had both issues.
Blown fuse and bad regulator in my 1995.
https://mbworld.org/forums/sl-class-...placement.html
Or just buy a rebuilt regulator.
Your choice. I had both issues.
Blown fuse and bad regulator in my 1995.
https://mbworld.org/forums/sl-class-...placement.html
Member
Joined: Jul 2008
Posts: 213
Likes: 31
From: SW Florida
1995 SL500 - 2017 AMG GLC 43
No, you could have blown a diode in the Alternator. From all that I've read, 75% of the time it's the voltage regulator. The regulator solved my issue. You don't have to remove the alternator from the vehicle to change it. Do remove the negative battery terminal before starting. You'll have to remove the belt from the pulley and remove one bolt to rotate the alternator to easily remove and replace the black plastic cover on the back of the alternator.
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Banned
Joined: Jan 2006
Posts: 1,982
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From: Atlanta, unfortunately
'09 S600, (2) R129 300SLs, '03 SL500, '03 SL55
You likely have a bad diode in the alternator. To test that you use a multimeter that has a diode testing feature, and you take measurements between the alternator case and its B+ and D+ terminals with wires disconnected from those terminals. With the (-) lead of the meter is on the case and the (+) lead on a terminal you would expect an open circuit; with the leads reversed you would expect to measure a voltage of around .8 volts.
