non typical lighting issue

[blue981.8t]

well first off new around here. been using the site for all the info i can find. been a big help. thanks

now as for my lighting issues. first time around it was the normal headlight switch contacts. cleaned the thing up worked for about a week. then they went out again this time i installed new switch an found a burnt up wire at the ignition switch. replaced the section of wire an the part of the plug that was melted. turned the light on an only running\parking lights come on. turn on rear fogs an all the lights worked. front an rear fog lights an low beams. that lasted aboout 2 days. now i turn on high beams those work fine as do all other lights except fog front an rear an low beams. so replaced the switch again hopping it was a bad switch. nope still nothing. is there a part of the lighting circuit i am missing? checked fuses, grounds, and traced the wires to the front head light plugs. all good. no brakes pinching or abrasions. the other day i smelt hot plastic smell so i checked the ignition again an no power to the switch for the headlights.
what i need to know is where the power source for the headlights is drawn from. or if there is a control module or something along those lines. ive replaced the ignition switch, headlight switch, length of wire that was burnt, checked grounds/cleaned, traced wires from switch to headlight assembly. an nothing still. im kinda lost with this hole headlight bs that audi decided to not do a recall on. i have to have my lights fixed before i get a ticket for running my high beams all over the place. an only time i drive is before sun up an after sun down. so my lights are essential an i bet people are starting to get pissed bc of the bright lights in their faces every morning.... any and all help would be appreciated thanks

[blue981.8t]

Well nice to see how helpful this site is. 👍🏻 it's all good tho, I figured it out. Headlights operational.

[SN95Audi87]

Well nice to see how helpful this site is. 👍🏻 it's all good tho, I figured it out. Headlights operational.

What was the problem. I read your thread but I never had a issue before. Is this problematic for the older B5's under 2000? Sorry no one responded.

[blue981.8t]

yes it is a very common problem with the prefacelift a4's normally its the light switch its self. but this time with me i 6 melted wires 2@ the ignition switch and 4 at the back of the light switch. 2 went to the fog light switches the other 2 were the output for the headlights them self.. thankfully i have a parts car an was able to pull the harnesses apart an repin them. also replaced 2 foot of each wire that was burnt up. still have yet to figure out what the cause was for them to burn up. checked and cleaned all grounds for the lighting system, traced wires to make sure there was no breaks, abrasions, or pinched wires. took me all day and half of last night to get it working again. hope this helps

[walky_talky20]

The cause is a lack of relays. Audi is running 100% of the power for the low beams and high beams (both can run simultaneously, mind you) through the ignition switch and the headlamp switch. All in, that's basically a 20 amp load. And all of this happens before the fuse box. So if anything tries to short out within the switches or whatever, it will just start melting down the harness. Good times. I have absolutely no idea why they think that's ok.

How it should be done (aka: how Toyota does it) is an under-hood fuse box with battery power, fuses and relays for the headlamps. The interior switches merely apply a piddly little ground signal to this bank of high quality Japanese relays. NipponDenso FTW. No over-taxed switches. No un-fused power running through your steering column right next to your airbag.

Is there a certain simplicity gained by eliminating the relays and having an honest-to-goodness switch that flips on the power to the bulbs? Yeah, maybe. But when said switch is plastic and of dubious quality, the simplicity gained is of no real benefit. The Germans, in fact, under-engineered this one.

[down_n_dapper]

boom. Walky nails it again ^^

The japanese do have some of the most reliable ways of doing things. Comparing the wiring on my brothers 4 Runner from 89 to my audi, his is much more robust, with ALOT more relays controlling seperate circuits, where as the audi from almost 10 years later seems to be cutting corners. go figure