Hey folks, I have the following problem:

I just bought an A4/99/2.8 and scanned using Vag-Com 401. It came up with the following fault code:

00526 - Break Light Switch-F
27-00 -- Implausible Signal

I checked the brakes and everything looked OK, so I reset the codes, scanned and everything was fine...so I figured the old owner fixed the issue before selling to me.

But now, I noticed that the low beam doen't work any more, on either side...only signals, fogs & high-beam work...did I screw anything up? How do I get the low beams back on? The bulbs seem to be fine.

The only mod I made was to put an aftermarket radio.

Thx

 

That's your headlight combination switch. Goes bad all the time. search "combi switch" and you should find loads of useful posts/threads

 

thx for the prompt response...I'll check the fuses and then look into the switch

 

OK, so I checked the fuses and they are fine...I've done some further research and it seems that this is a common problem with the B5s...the DYI seems pretty straight-forward, but knowing how "handy" a man I am - had it not been for the airbag, I'd probably go for a few shots of scotch and start right on it - maybe I'll look for someone that's done it before and can help me...or take it to an indy shop (how big a job is this... like 1 hr?).

Also, wouldn't it be better to replace the relay completely?...I mean, if this started to melt, won't it happen more often from now on? Thx

 

I've done the DIY, its really not hard. Just be careful when removing the airbag. You're probably right, if the switch started to melt, completely replacing it would make sense, but the DIY is free, a new switch is not. Also, be careful when you take the switch out of the steering column, there are several small springs in there that all want to GTFO when you take the switch cover off. Don't shoot your eye out!

 

Shouldn't have to pull the cover off if you're replacing the assembly. Before replacing it, you can see if you can fix it (I have fixed a couple and found some that were too far gone). Take it apart and watch how it's set up - it's pretty simple but take a pic before you remove each section as a reference). What you'll find is that the slider across the bottom of the housing is melted, and in the bottom there are two metal contact bars. Likely the rear one is warped and pulled up and away from its contacts. If the warping is minor, some handy work with an X-acto knife and sandpaper may be all you need to repair it.

And yes, meltdowns will continue. There are no headlight relays in the car, so bulb current is drawn through the switch. I'm working on a retrofit of relays to the car so that only the activation current for the relays will draw through the switch and this type of meltdown should be a thing of the past. It'll be posted with a step-by-step, pictures, and a tool/parts list once I'm done.

 

Is there an average ETA of meltdown between repair intervals...6 mths, 12 mths, etc?...I'm trying to get a sense of how often this happens...also, would an add-on in-line fuse help reduce the heating issue?...I guess replacing a fuse more often would be easier than taking the wheel apart?...no expert, just a thought (of course you'd have to know what the nominal current draw is)

 

I'm on my third one in three years (although my replacement switches have been used parts). I doubt many, if any, of us are original owners so it'll probably be hard to get a real feel for switch longevity. There are individual fuses for each headlight already but they're in place to protect against overcurrent. It's not that you're getting a spike that's killing the switch, it's that the heat from the current draw over time melts the chintzy plastic contact slider. I'm hoping that by installing relays to control the headlights, longevity will be greatly improved since the current needed to trip a relay is far less than that needed to drive halogen bulbs or HID ballasts. Less current means less heat and therefore less of a potential to melt the switch slider.

 

10-4 !

 

BTW.. The code you pull IS NORMAL! Next time you run the scan, clear the code and push in the brake pedal while scanning... it'll go away.