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Right Low Beam Not Working

The Wave

G-Wagen Club SA
Joined
Aug 8, 2017
Messages
27
Likes
3
Age
37
Location
Cape Town South Africa
#1
The right low beam on my W460 is been intermittently working / not working for about a month. The left headlamp is working perfectly, and the right parking and high beam are both working. Its only the low beam that's a problem. I had a look at the connections and bulb today and found the following:

There is correct voltage to the low beam elec connections
The low beam part of the bulb is working when tested with an alternative battery source
I hooked up additional wires to the connection points at the bulb, turned on the lights, and the voltage is good until the bulb is connected, then there is zero voltage.
The right bulb, and left parking and high beam are working, so I have assumed the switch in the dash, the fuse and the battery are fine.

I imagine it might be the relay?
Any ideas for another test I can do, or where to locate the relay to check?
 

Andrew

G-Wagen Club SA
Joined
Oct 8, 2008
Messages
3,436
Likes
337
Location
Brits
#2
Dave, unless a relay has been added afterwards, the lights are connected directly - left and right are seperate circuits - ie the full current runs through the switch and the combi stalk to the globes. If there is any dirt in the system trouble starts. I would start with cleaning the fuses and the holder - i think your trouble is there. Perhaps you will feel one of them is hot and then its easy.

If not and you have the old rocker light switch on the right of the steering wheel I would suggest adding relays as those switches are very unreliable under load. If you have the very reliable rotary switch in the centre console and the fuses are not the problem I would next remove the combi switch and spray switch cleaner into it.
 

The Wave

G-Wagen Club SA
Joined
Aug 8, 2017
Messages
27
Likes
3
Age
37
Location
Cape Town South Africa
#3
You were spot on Andrew - it was fuse 6 that looked fine, but there must have been a bad connection.
I have the centre console rotary switch - no problems there.

After your comment, I had a look at the electrical wiring diagram and was surprised to see that half of the fusebox is dedicated to the 2 headlamps.

Thanks for the help!