Electrical

Headlamp Bulb Wattage Upgrade Warning

Mike Brannigan wrote to the list:

>> quick question - last night my passengers headlight went
>> dim... not out, but a sickly yellow.. I drove with the
>> foglights so as not to look uncool, and then tore it apart
>> when i got home. (i assumed those housings were aluminum..
>> pretty nice paint job for a plastic part..)
>>
>> I found that the bulb was okay (an 80W/100 - is this stock?),
>> but that the harness is starting to fry itself... I cleaned
>> the contacts with a nail file, and put it back together..
>> light works great.. but what would have melted the harness?
>> I'm wondering if the 80W bulb should really be a 55W bulb,
>> and it's pulling too much juice through there?


Hi Mike:

As Ed R. has already pointed out, the original bulb is not the 80/100. You don't say what year your car is, so the bulb type may or may not be the same as mine. Got an S4 or newer with H-5 style lamps and a 9004 bulb? That's what mine has, and upgrading to the 80/100 bulbs caused me symptoms just like the ones you report. On my '89, the bulb socket and the wiring just behind (towards the rear of the car) the bulb was melted. Strangely, it was just the brown ground wire that was damaged. Once that connection opened, the two bulb filaments (main and dipped beams) were essentially in series with each other, and also in series with the main beam filament on the other side. That's what caused the light to glow yellow-- each filament was only receiving about a third of it's normal voltage.

The solution was/is a replacement bulb connector. I found one at the local parts place, with short pigtails attached. The wires to the original socket get cut, and the new socket is attached by soldering the connections and protecting them with a little heat shrink tubing. Now I should have been smarter when I did the first one, and just replaced the other at the same time, but noooo! A couple weeks later the second lamp faded to a yellow glow, so another trip to the headlight bulb socket store and another half-hour of soldering fun was added to my maintenance logsheet.

The replacement sockets are hi-temp plastic, hopefully more durable than the nylon parts that were original. The biggest improvement is in the contact to the bulb itself, where a real copper connection replaces the original zink- or tin-plated contact ribbon.

A year after the socket episode(s), all is still well with the 80/100 bulb conversion. About the only downside is that the replacement plastic sockets are blue, so a concourse judge might ding me a couple points for not having the melted faded-to-yellow nylon OEM parts in there. It's a worthwhile tradeoff in my opinion.


dr bob