laissezfaire

I know there are relays under the driver side dash... any ideas on what would cause one of them to click/pause/click (and flicker the headlights, if at night) whenever I lift the throttle?

It's a mystery to me. No codes.

Chris's S4

I have a question... you posted this in two different sections... A4 and S4.... That messes with my conclusion of what the issue is.

It is in fact an S4.. Then I think I got what the relay is for. If it's an A4.. then I'm slightly screwed. I have a real good idea of what it is. The problem being A4 and S4 car type. S4 has turbos.. A4 doesn't ... many of you are thinking well duh but what the hell does that have anything to do with it.

Well on a turbo powered car, Im thinking (could be wrong don't bite me for it) because intake air is pressured by the turbos it causes a negative affect of the intake's vacuum system. Now again wth does that have anything to do with the S4.. well.. the intake's vacuum system is what powers your brake booster, am I right?... yes. Well what happens when turbo boost comes into play into the intake... it's no longer a vacuum sucking air in. It's a high pressure area "forcing" air into the cylinders. Thus causing a negative effect on the brake booster now cus it has no vacuum... So what do ya do... ya put a vacuum pump on the car, to trigger at specific moments of the throttle range to activate and cancel the pump.

If any of you have ever had the knee bolster off and drove the S4 and listened to the relay that makes the sounds of, on and off while your on the and slightly off the throttle.. then you'll hear sometimes at stop lights you'll release the brake pedal and hear a refilling(sucking) sound?... have ya?.. I know I have. that's your brake booster refilling with vacuum from the intake, due to the system now having vacuum and no boost from the turbos. So the original system resumes and the vacuum pump shuts off. That's where this relay comes in, that flipping of the relay causing the ark/current flow disruption.

Anyways, that vacuum pump doesn't just supply vacuum to the brake booster, it's supplying vacuum to all components that rely on vacuum to operate the car. Thus why we have the vacuum pump hooked up directly at the fuel rail. To supply vacuum to all vacuum operated units.

I had this epiphany the other day just after searching for relay location and purpose lists.... So couldn't really find what I was looking for. But late that night driving home after a night of watching some street runs. It hit me... my cars turbo charged.. when ya have a vacuum system.. you loose the vacuum and get pressure due to the turbos.. so that giant check valve on the right side of the throttle body closes, and the vacuum pump come into play.

Now that relay is prob not very happy considering it's causing a flicker in the main headlight bus... So I'm gonna try and trace the wiring, (use bentley and Elsawin) to find out why it's causing this. It could be a bad ground or simply the fact that, that relay operates so frequently it's points have become burnt so to speak.

Now I did notice (hence why I mentioned early about driving throttle with your foot) that when cruise control is on... that relay operates slightly less than the amount of time it does with cruise control off. So... still does it.. just not a 100 times... maybe only 98 times... lol

Anyways don't flame me on this, it's just a theory, I believe it. But doesn't mean you have too. I'm always welcome to others who have an idea of what it is and what not. Im just throwing this out there that way, maybe... just maybe it's something so stupid as a relay change (new one) or something again stupid as pulling a wire off that bus and moving it to another bus.

I'm going to find the way to get my lights to quit flickering. It's a guarantee.

Hope this helps someone, also revive this issue into current events so we can solve this nonsense ASAP! Enjoy...

Chris's S4

Alright so today I took a closer look at that relay that clicks under the dash.

Turns out it's cycling the abs pump. Why... no idea. Maybe it's the way the system works when the brake is pressed, the pump "prepares" its self for the possible "slamming" on the brakes and abs kicking in? who knows at this point. I'll have to run more tests.

One test I did run was removing the relay, took a drive and tested the brakes. Note: ABS and ESP lights stayed on. Testing the brakes turned out to be skidding tires... Go figure. Plugged the relay back in, restarted the car did it all over again.. Abs kicked in like it should. Oh yes, also ABS and ESP lights turned off once the system check was complete and found the relay in place.

Why would the ABS pump need to cycle with each slight flicker of the throttle... I dont get it.

And it's not the vacuum pump. But that whooshing sound still has to be the booster filling with vacuum. Has to be.

Chris...
(gonna go bust a few walls in with my head maybe the walls will knock some idea of what this problem is, into my head. lol)

Time to drink... lol

Chris's S4

UPDATE!!!!! Yes I know it's been months and months. But I've found the solution to the random relay clicking, Xenon headlights flickering, and lastly the famous rear brake random lock up!... Yes I've found it.


Turns out after long tests and many many nights of scratching the head at why the rear brakes kick on and headlights flicker due to some relay clicking when the brake pedal is released or throttle is feathered on the fwy. The culprit you ask, well that's the good ol' wheel bearing. And now you ask well what the hell does a stupid wheel bearing have to do with the brakes or even the damn headlights!

Well... EVERYTHING! That is when the wheel bearing begins to fail, what does it do? It begins to allow the axle to travel up, down, pretty much in every direction. And what does this do in turn to our equipment?? well that little abs ring inside that hub starts to rub against the inside of the CV housing (hub). When this happens it causes the ring to get chewed up and literally grind itself down. To the point that the wheel speed sensor can't always pick up the correct reading, thus falsely activating the rear brakes only and prematurely. I also tested how it reacts to the steering wheel due to the clock spring with angle sensor, it actually increases the chances of "brake stab", which is activation of brakes abruptly.

Now many of you are probably saying, well that's not true cuz vag-com says my wheel sensors read correctly all the time... Well.. YOUR WRONG! sorry... well no I'm not. But your still wrong very much so. And why, simple because my system I have in my car, I can read my wheels speed directly on my dis, and all my wheels say the same... speeds are match and are good. Now your gonna say well my ring was cracked... well no it isn't. My ring had just enough finger depth to read and work correctly most of the time. I'll post a picture of it... it's 3/4 worn down... yet still worked, oh also my sensor has been chewed up by the ring due to the bad wheel bearing. So all in all, my read outs all read correct. even tho I knew i had a bad ring. Either way I still had the problems constantly.

So the solution, many of you already know. Buy a new CV.... well once again we're right back to.. YOUR WRONG. I say it out of love. does that help? Anyways, I know I know... all of you are saying wtf!... well in fact buying a new cv to get a new ring is in fact mostly the only way to repair a "bad" ring. But not anymore...

No need to spend 85,95,100 dollars in new cv's or even axles as some of you had done that. I've got many of these rings and if anyone needs to replace one or more, then let me know.

The solution to getting your lights,brake system and random relay clicking. Is to replace that bad wheel bearing and the abs ring thats bad on that side. Then the all the systems will go back to normal. I've been click free, flicker free, and brake stab free for almost a week now... AND DAMN DOES IT FEEL FREAKIN NICE!!!!!!!

Send me a PM if ya need the replacement rings. Mind you, you wont find them anywhere... Germany sells them at $125 (75 euro) a piece. And no one else anywhere has them. Trust me... If I'm now writing this post... months later, after declaring that I would fix this problem... That's why, cuz I spent months trying to find these rings.


Hope this helps some one out there with this problem.
Chris

dapinitial

I joined specifically to talk about this. I have an S4 I’ve been tuning. Ever since an engine swap to a Canadian engine into a Canadian car JHM tuned and lots of goodies all around I developed this gremlin. At slow speeds click click click. I have lived with it for two years after looking into all the usual suspects. No codes. No ABS lights. No known issues… wheel speed sensors show accurately… but maybe you are onto something…

I know it’s the ABS module because when I unplug it the clicking goes away. I plug it in and that click click click like a solenoid engaging. I currently have the car in dealership after replacing the module myself, bleeding the brakes, and coding the new module and the clicking remains. I swapped ABS module to a new one no codes… ABS works but click click click. No codes. When I pull the ABS plug the ABS, ESP etc dash lights come on. Clicking goes away. When I plug it back in clicking returns, lights go away. I guess I’m going to procure these Audi S4 B7 ABS rings and try…

How did you go about diagnosing which one to replace???

anyone else have this problem? What is the fix?

dapinitial

This only happens to me when braking at slow speeds. First I thought was pads and rotors. I changed all that, the entire suspension. I did everything. Everything works. Car feels great. Just this annoying click click click as I’m braking at slow speeds. It wasn’t there before the engine swap. It was observed afterwards. No lights no issues. Tried everything. Now brought to the shop with another module installed. Same problem. I have the original module still… I can put it back… but I think these ABS rings are indeed the next logical step. How can I determine which needs attention?