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Halogen Left Dipped Beam Not Working
I have a Audi 2008 A4 B7 Avant.
My left side halogen H7 dipped beam has stopped working (right side is working). Dash warning "Left Dipped Headlight" 1. I have a few H7 spares which I tried a couple of them with no luck. 2. I have tested the voltage on the plug for the globe. No voltage present. 3. I have pulled the drivers side cover off, whilst there is nothing labelled for headlight fuse location I have tested both sides of every fuse and they are good. 4. I have the workshop manual. Couldn't find headlight fuse location. 5. Googled and searched this forum for last hour and haven't found anything useful as yet. 6. I also tried turning key off plugging in globes and then ignition back on as with the Audi's lighting system once a blow is detected it will stop powering that globe until next key off/on. I have seen people talking about a headlight fuse breaker rather than a fuse, but no one has indicated where it is, which makes me feel like this is just gossip rather than fact. I have seen talk of the headlight switch I haven't checked as yet. If anyone had success in finding a fuse (or the location of the breaker, if it exists) would be helpful. |
Update: 17/11/2019
I came across this post in another forum by ImTheDevil suggesting there is no fuse and the lights run directly through the switch. There is no relay. Headlight current goes directly through the switch. The contact is a small copper rail in a plastic piece that (when the lows and front/rear fogs are all on), has 23 amps flowing through it. The heat melts the plastic, lifts the rail, and breaks contact with the switch outputs. It's a design flaw, there is no recall, and your switch is dead in this manner. The highs work when pulling the stalk because it uses different contacts when toggled that way, and doesn't use the regular light contacts. Replace or repair your switch. A whole switch on ebay is $17.99AUD (approx $13USD) The only PINOUT I could find for this was a photobucket picture which I had to keep refreshing the page and trying to get a screenshot as photobucket kept blurring the picture out this is about the best I could get without wasting too much time, but you can make out the pin connections which there is only 1 pin for the headlights and not left/right. https://cimg3.ibsrv.net/gimg/www.aud...3e4c3284ab.jpg Audi B7 Headlight switch wiring/pin configuration. |
Update 17/11/19 (afternoon)
Having now seen that the headlight switch only had a single feed and when tested with voltmeter it works correctly, I have come across another post which Woorlord gives some good info on the Onboard Power Supply Control Unit referred to as J519. From Woorlord's post on other site; t's a little more complicated than a simple switch and relay but still traceable with a Multimeter tracing the volts with respect to chassis........ The light switch is directly connected to the "Onboard Power Supply Control Unit" module (J519), which in turn supplies each bulb front and rear. The OPSC unit effectively is a big clever relay and bulb failure sensor feeding the DIS, as well as loads of other functions. FUSES: The main fuses that feed the OPSC unit are: S36 = 30A S37 = 20A (30A with headlight washers) LIGHT SWITCH: The light switch connections..... Switch Positions labelled: 0/1/2/A Switch Common: Pin 15/30 = +12v supply (red) -from- J519:T32b/24 (without coming home lights / with coming home lights +12v supply from point A57??) Pos.1: Pin 14/58 = sidelights [position 1] (grey) -to- J519:T32b/25 Pos.2: Pin 11/56 = dipped [position 2] (yellow) -to- J519:T32b/26 ****T32b = 32 pin grey connector on OPSC. OSPC Unit onwards: The "dipped" connections out of the OPSC unit to the headlights are: Dipped Beam (L) J519:T23/23 (yellow/black wire) -to- T17a/16 -to- L Headlight connector 5/56b -to- Bulb M29 Dipped Beam (R) J519:T23/22 (yellow/white wire) -to- T17ac/16 -to- R Headlight connector 5/56b -to- Bulb M31 The other side of the dipped bulbs are grounded. ****T17a = 17-pin red connector A-pillar left ****T17c = 17-pin red connector A-pillar right It could be that your OSPC unit has gone faulty?? Perhaps possible to connect up to VAG-COM and see if there are any errors logged?? OSPC unit is "09: Cent. Elect." Audi Part No. 8E0 907 279 ? ........ mine is version "B" 2 Faults Found: 00978 - Lamp for Low Beam; Left (M29) 30-00 - Open or Short to Plus 01800 - Light Switch (E1) 27-10 - Implausible Signal - Intermittent I know from this post which relates J519 on a VW Beetle that M29 mentioned in my faults is located on J519. The module is located behind the dash on the drivers side and can seen with a torch when you take the fuse panel off. To get to it you need 8mm socket to remove the 3 bolts holding the lower under the steering wheel and then wiggle the cover off. https://cimg3.ibsrv.net/gimg/www.aud...f7329cbd93.jpg J519 Power Module located behind drivers side dash near fuses. Once in there look for the T23 plug which is the black (not grey) plug with varying wire gauges. You can then with you tester back probe PIN 23 (note pin numbers are found on the plug if you pull it out and inspect) which is the left hand light it's the Yellow wire with Black stripe. Turning on and off the light switch should show output. https://cimg8.ibsrv.net/gimg/www.aud...0af98f0551.jpg J519 Power Module plugs and left dipped head light wire location. If you have output then the output heads further along towards the lights to a red 17 pin connector "T17A" located on the A pillar (supposably) and then onto the plug that plugs into your headlight assembly and then lastly the plug on the globe. I am going to continue following the circuit I promise to post my solution.. once I find it! |
Found it.. I was getting voltage all the way up to the headlight assembly plug but nothing on the H7 headlight globe. I pulled the bumper slightly off and pulled the headlight out and then inspected inside the assembly and found wire broken. Would have been a lot shorter job if I looked here first but I become so immersed with finding the headlight fuse I got side tracked. But in the process I think I have done a stirling job of documenting the A4 B7 headlight circuit for others to take advantage of.
So to summarize; 1. There is no headlight fuses! The A4 has what is called "Onboard Power Supply Control Unit" referred to as J519 (the B6 I believe has fuses..not the B7). 2. The J519 takes voltage from the battery and then supply's power to the various switches (eg light switch) and takes stat changes back such as headlights on. It then supply power directly to the lights. 3. As J519 is computerized you can use VAGcom to read it through the OBD-II connector. 4. Getting to the J519 takes less than a minute with a 8mm socket by removing the 3 bolts and wiggling cover under the steering wheel off. 5. J519 does have some big fuses these are not for the headlights, they are more common fuses eg supplying J519. |
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