Good info Mark, but from my experience they did this new, just not enough alternator when even my '85 Jetta had a 90a alternator as standard. My '91 had heated seats, heated mirrors, heated washer nozzles, heated rear window, lights everywhere, ... some of it can't even be turned off in cold weather and it wasn't enough to keep up at an idle. Many times I'd see my seat-heater switches and rear-defogger switch lights blinking which indicated that the voltage was too low and they shut themselves off, ... when the car was new. The VR did fail on that car when it was about 4y/o, a new M-B alternator had the same weak output at idle (which is why the auto-off circuits were on the bun-warmers and rear-defog, Mercedes knew that it was necessary). It clearly should have had a nice internally-regulated 110a-150a like all of its competitors were installing.

Upgrade, it's easy.

The end result is that your battery will last MUCH longer. Every time you idle and the battery discharges slightly (or it interrupts a charge cycle) it shortens the life of the battery, just the nature of a flooded-cell battery. The proper alternator will pay you back in battery life and warm buns.

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Gone to the dark side

- Jeff