Aux headlight fog lamps and after market fog lamps - Benzworld.org

alc · 10-28-2005, 09:08 AM

How do the fog lamps in the headlight cluster work? I have the wiring harness and intended to mount a set of Pia's to my either the grille guard or bumper cut out for my 00 ML. I understand that the dealer must activate the switch. If I install bulbs in the aux fog lamps in the headlight cluster and to the grille guard will both be turned on when the switch is activated? What size bulbs are used for the fog light in the headlight cluster?
Thanks in advance.

majorkahuna · 10-28-2005, 09:19 AM

The reason the factory fog lamps are not installed is that they are only legal in 18 states because of the height above the road. I live in WA and they are legal here so I had the dealer install and activate mine. They can program either or not both.

rudeney · 10-28-2005, 12:54 PM

On most (if not all) MY2001â€™s, the switch came activated from the factory. Your MY2000 may have it activated â€“ I think many were. Itâ€™s mainly the 98/99 MYâ€™s that had to be dealer-activated. Even if your switch is activated, you probably wonâ€™t have the instrument cluster indicator activated, but then again, you might not want it â€“ itâ€™s as bright as the high-beam indicator and can be annoying. You can test to see3 if your switch is active by starting the engine and pressing the AUX switch. Check the voltage on the connector (you should find it on the right side of the radiator, usually with a lable).

majorkahuna · 10-28-2005, 01:02 PM

The switch is active from the factory, but the programing defualt is for the lower wiring harness. You have switch to the upper harness to use the built in fog lamps, oh and add the bulbs.

Noodles · 10-28-2005, 02:27 PM

We had to have the dealer activate the aux fogs in our 99. I added a brush gaurd and put the MB Hellas on and now all four fogs light up. Plus the two headlights. I know it is not legal to have 6 bulbs on, but I can see things very well at night and the dealer can't get the computer to shut off the aux ones and still leave the Hellas powered.

rudeney · 10-28-2005, 03:54 PM

Quote:

majorkahuna - 10/28/2005 2:02 PM

The switch is active from the factory, but the programing defualt is for the lower wiring harness. You have switch to the upper harness to use the built in fog lamps, oh and add the bulbs.

Hmm, I wasnâ€™t aware of a setting that controls which harness is active. My understanding is that both are active or both are not. This would also seem to be the case in Noodles example, he obviously has both active since his build-in fogs and his bulbar mounted fogs are working. Also, I know many ML owners have reported having to have their fogs activated just to get the â€œlowerâ€? harness to work in 98/99 models.

bigcatny · 10-28-2005, 04:31 PM

On the 98's and 99's when the fogs are activated it's both on or all off Definitely....... Apparently, the problem is that having both sets of fogs on and running puts too large a strain on the wiring and circuits. I think fuse blowing and wiring harness melting has been mentioned.

If you don't want the fogs on the headlights ON then pull the bulbs.....

After I switched to BiXenons, I never missed fogs in the least.

alc · 10-28-2005, 05:11 PM

Would California be one of those state?

alc · 10-28-2005, 05:12 PM

Thanks for the info.

Noodles · 10-28-2005, 06:06 PM

Quote:

bigcatny - 10/28/2005 5:31 PM

On the 98's and 99's when the fogs are activated it's both on or all off Definitely....... Apparently, the problem is that having both sets of fogs on and running puts too large a strain on the wiring and circuits. I think fuse blowing and wiring harness melting has been mentioned.

If you don't want the fogs on the headlights ON then pull the bulbs.....

After I switched to BiXenons, I never missed fogs in the least.

Well we intially had some fuse blowing, but is was a bad wiring job during the installation at the dealer, so they fixed it and it has been fine for a long time. The dealer showed me the wattage of the the aux fogs and the total extra drain on the circuit was <120watts. They told me that it should not hurt anything. I was worried about the harness and told them that. They explained to me that if had been left wired the way it was and it was fixed by putting in a 30 or 40 amp fuse instead of the OEM 20 amp fuse, then all hell would happen with the harness. Apparently some dealers did try to fix it that way, thus the melted harnesses.