I have a just broken-in 1988 300E (336,000 miles)
My major problem right now is that I am burning up
the ground pin on both headlamps. The problem occured
years ago with the stock connectors and DOT approved bulbs (dull). I replaced them with 80-100 bulbs a few years ago along with a custom heavyduty wiring harness from Competition Bulbs. The problem went away but is now back badly burning up connectors as fast as I can buy them. I am now only using DOT approved 9004 bulbs, the heavy duty harness and a heavy duty ground wire directly from the connectors to the battery "-" post. I had this problem start years ago with the factory connectors and bulbs.
Any ideas? Thanks
GTF

First and foremost, welcome to the site.

Sounds to me like there may be a short somewhere, but I'm no expert.

I would check out this site to compare your custom wiring with to see if it fits that scheme. It may help. http://lighting.mbz.org

Have you checked out your grounds for the wiring, including stock wiring?

How is your alternator? is it overcharging perhaps?

You may want to entertain switching over to European headlights. With stock 55w bulbs, I am getting a better beam pattern and light output that makes the stock headlights seem like candles in comparison. all this With the same standard watt rating as the stock bulbs. Price is not too expensive, and an easy DIY project.

I hope some of this helps.

Alon

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'92 300CE - Sold
2004 C240 - 744 - C7 Wheels - Android Radio
2002 C320 - 816 - Sport Wagon