Just purchased a clean, original, CLK convertible with 73k miles. It had the disintegrating wire harness problem in the headlight housings. It has the halogen headlights NOT the xenon. Installed new Hella assemblies that came with Hella bulbs. Note: the bulb failure notice does come on in cluster.
PROBLEM: left high beam will not come on still in either "flash" or switched on modes.
Tested so far:

1. Fuse, OK, voltage at fuse with switch on, OK
2. swapped bulbs left to right, left not still working
3. checked connection at assembly. One circuit does NOT have power regardless of switch mode. this is the wire opposite end of the 4 pin from ground. Sorry, forgot the color code.
4. common ground and other bulbs work, so, eliminated that.

I cannot find a wiring diagram, so, reaching out for help.

• Is there a separate headlight harness or is it combined with the engine harness on these cars?
• Is there a control module in the headlight switch that would control the high beams?
• Is there a relay, if so, where controlling the high beams? Is it separate for left and right? Since there are separate fuses for left and right high beams (and lows) I'm thinking a control module not a relay. Please advise.
• Any other test points I can meter?

Any help is greatly appreciated. I really hate to start buying parts without diagnosis. the headlight switch is $300, ouch!


Brian

Update, After troubleshooting the system to death, I went to the local junkyard that had a fresh kill '99 CLK. took the headlight switch out. A lot of things to disassemble, but, doable. Installed the used switch and all lights are now functioning. It seems the bare wire in the headlight shorted something in the switch/fuse block/module and destroyed it. Had to pay fuse box price, $18. So much better than $300!

yeah the headlight switch design has proven to be a weak spot around that time

__________________
-- raymond~
47º 34'N 122º 18'W