Okay, but as the radio announcers say, "But wait! There's MORE!"

I removed the bulb and tested it with my dvm and it does show open. Now I replaced the bulb with the new one, turn on the ignition key and the headlight switch, no light.... hmmm... So I remove the NEW bulb and test its continuity with the dvm, shows about 13 ohms. Ok, that's a static test, so I put it on the bench with a 12 VDC power supply, bulb works admirably. I check the power at the contacts of the mating area of the control module, turned on the lights and it measured 12 vdc, so there IS power to the light socket (how much current is available at 12 vdc, I don't know as yet).

Now the weird rookie question: I was reading a thread somewhere along these lines that mentioned a "rheostat". Does this model have one and if so, where the heck is it? ha ha ha!


Later that same day!

I finally discovered the problem. I took the intricate little "socket" into our lab and put it under a microscope. The socket is an assembly consisting of 2 nylon parts and 2 metal parts. The 2 metal contacts appeared to be both dirty AND corroded from the heat of the little bulb. Using isopropyl alcohol (also known as isopropanol to some chemists or RUBBING alcohol to us southerners!), I cleaned the entire thing, brushed the contact areas a tiny bit, bent the two outside contact areas UP a little, then reassembled it.

I put the assembly back into the module and tested it and it now works!

I'll try and take a few pictures and add to this thread later if anyone would like it.

Hi Clankford,

Nice to see another electronics guy on the site. First, if you have a good bulb and you have 12V then explain to me why it doesn't light up??? Well, either you have a high impedance path or a bad connection right? So check your 12V at the bulb with the bulb connected. My favorite saying as a bench tech was "if you prove that it must work then it will work". As far as the rheostat, the dash light brightness is controlled by the "+" "-" buttons which are above the "0" button (odometer reset) on the lower left edge of the inst panel surround. I assume it would control that bulbs brightness also but I don't see what that has to do with anything. Anybody with FR4 in their garage should be able to fix a light bulb!!

Mike

__________________
1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra

Ha ha ha! You would think that, right? Sometimes I amaze myself at my own stupidity and ineptness. But I don't keep FR4 in my garage.... er, uh, at least not MUCH FR4. I had it at my job.

I had thought that I might be dealing with a high impedance issue, so I decided to check all the contact areas first.

Well, it is working now, but dimmer than I would like, so the next time I go by an MB place, I will get the exact bulb replacement. My finance is heading south to the coast in my Benz, so I am trying to get all those last minute things fixed.

Thanks so much!

Your "finance"? Is she costing you that much???

MP

__________________
1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra

Haven't you ever wondered why there is only ONE letter difference between Fiancé and Finance?

She's driving MY Benz, what do YOU think?? Ha ha ha!

Curt

Well, you know there is a reason that there is only ONE letter difference between "finance" and "fiance"!!!