Light Control Unit?
 

Hi All

Had a very strange problem last night. My "light out" warning light came on, I checked and the RR tail light was out. Checked further - it was not the bulb but there was little or no power to that ciruit, fuse #3 was ok and all other lights on the circuit work. Checked up on the Haynes manual and it showed a "light control unit" that the lighting wires pass thru that also control the warning on the dash.

But this morning, the light worked again! Can someone shed some light on how this works and where this control unit is located? Is it as complicated as i think it is or is it a straight wiring from fuse to switch to light?

Thanks!
Oreo

I'm chasing down the exact same problem on a 1992 500E. The right rear tail light is out, bulb is good. I have resoldered the connectors at the tail light and just this morning I pulled the Light control unit and resoldered everything on both boards. The problem is intermittent so time will tell.

TCG
1992 500E
1986 300E
1975 450SL

Hi TCG

Whereabouts is this light control box? I think its one of the relays behind the fuse box. Is the really long one? I cleaned up all the fuses (again) and so it was ok again last night.

Oreo

Oreo,

It is the long box on the outside under the screwed on fuse box cover. There are 3 connectors on the bottom. With a little patients you can remove the cover of the unit and get to the circuit boards. I resoldered all the solder joints. I've repaired many MB modules by resoldering. As of tonight mine is still fine, but it has gone weeks without malfunctioning.

Goog luck,

TCG
1992 500E
1986 300E
1975 450SL

Hi TCG

Thanks very much for pointing this out. When it misbehaves again, at least I know where to look.

Regards
Andrew