Richard,
Make sure the auxilliary water pump is not glitched and pulling more than ~1.3 amps. When it does it uses the PBCU as a fuse! Honest. Interesting MB "feature". This may explain the burned traces or it may not.

__________________
The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)

Thanks for the advice. I just finished reading a thread over at the diesel forum in which several people stated that.

So, before I even look at the service manual, let me ask you these: 1) where is that aux. water pump located in my car? 2) How do I measure how much current it is drawing?

Thanks,

Richard

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1999 Mercedes-Benz S600, 103K miles - garage queen
1988 Mercedes-Benz 560SEL, 89K miles - daily driver
2007 Hyundai Sonata Limited, 31K - daily driver

It's sort of under the monovalve between the two firewalls. Just pull the plug and test it or leave it unplugged as it is only useful at idle in cold weather.

__________________
The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)