keshavbirla

Hello

I have a 2001 Audi A6 2.7T (Manual)

I have few issues going on with my car -

1) It started with, when one on my rear indicator and brake light bulb died. My dashboard produced an alarm "Brake Light". I had replaced both those with a sylvania bulb. Although, after replacing the bulbs, the bulbs started functioning, but everytime I brake I would get a "Brake Light" beep on my dashboard. I thought there would be some resistance difference between original bulbs and the new sylvania bulbs, so I changed all the rear bulbs (even those which were working fine) with the new sylvania bulbs. That did not fix the issue. I also had few leds blown on my third light, so i changed those leds as well, but no luck; dashboard still beeping.

The next day, something new happened. During daylight, when my headlights are turned off and then when i hit brakes - dashboard will beep with "Brake Light" Warning; while during night when the headlights are turned on, then it is not when I press the brake, but when I release the brake the dashboard will beep with "Bulb Failure" Symbol.

2) After couple of days, my cruise control started acting weird. It works fine during day time, when my headlights are not turned on; but as soon as I turn on my headlight the cruise control stops working every time.

3) I have also noticed, that while braking; both my front indicator lights glows as well along with the rear brake lights.

I feel all these issues are connected, as all these started when I changed my first rear brake light bulb. I now realize I should have bought the original bulb; but now since the mistake has already been done. I would need some help or suggestions from you who understands whats going on...??

Thanks in advance.

tester123

It is possible that you might need a new Hazard flasher module. It is the module beneath the triangle button for hazard flasher. I know for sure it has relays that control signal indicators.

The bulbs you have replaced, did you cross-check and found the right wattage or, simply picked up something else? You don't need original bulbs for it as long as they "match". Auto parts stores should be able to get you right ones. Make sure to check against original.

The cruise control stops working because the "brake" light is being triggered. So, you need to check the brake light switch as well and make sure it is working or needs replacement.

Harleyguy

Not 100% sure, but does sound like hazard module is causing the problems. Bulbs need matched so as not to unbalance the load on the circuit.

keshavbirla

I took the original bulb to Advanced Auto parts shop and the person there matched the bulb and gave me the new bulbs. Today I compared the original and the sylvania bulb, the original bulb says 12v 21w; while the sylvania bulb doesn't mention any wattage on it.

Also, my indicators and hazard lights are functioning properly; do you still think it could be hazard module which might be causing this problem?

And, how do i test brake switch?

Der_Echte

The rear composite light assembly is an "interesting" engineering design. For the Brake light and turn signal, there are bulbs, but the signal goes through some physical connections that are also "Interesting". The assembly is like a two piece design, inner and outer pieces. The inner piece has a maze of circuit board like stiff/semi-flexible physical tiny arm circuit connectors that bring the electricity from the wire to the bulb.

Since these can un-bend and move over time and lose connectivity (or even worse, provide intermittent connectivity) you can be a not so happy camper real quick. Sometimes, you could drive a few miles, shut car off, restart and have no brake light issues. The new assembly on Amazon is low 100s USD, but often, you can buy some time by cleaning off the physical connections and bending them outward to restore a more stable connection. Despite your best efforts, there will be a day where you lose connectivity again.

I would say try checking connections on harness connector and clean/bend out the circuit card like arms first, it is good experience. One day, you might just need to replace the unit, it isn't overly expensive and should give you years of good service.

I do not know what to say for your cruise, but to fix the"easy" light issue first.

Der_Echte

The fog light, brake, and turn signal are bulbs, the top LED is tail light.

johnkk

Again. Wrong forum. C5 bulbs are not led. Re: c5 question, I have had better luck when all bulbs have grey contacts and not brass.

tester123

Doesn't the package of new bulb indicate wattage? The indicator/hazard flasher circuit also senses burned out bulbs and prompts warning in the gauge cluster / dashboard. For this reason, you need the right wattage bulb to make sure "loads" are proper for the circuit to function correctly.

As far as the brake light, check normal operation first. Have someone look at the lights when you press brake.

The reason why cruise could be "disengaging" is due to its normal operation. As in, when you are in cruise mode at certain speed, pushing brake once will stop cruise until you press "resume". This is normal. So, if the brake indicator circuit is being triggered by the brake switch or if some how the flasher module is triggering (I did not verify the circuit diagram for actual trigger to disengage cruise), this would stop cruise.

The test to isolate any cruise "malfunction" is to drive in cruise for a while and WHEN it stops abruptly, press "RESUME" and if cruise resumes, then most likely it is the scenario I have described above.

First sort out your bulb situation. Then perform the cruise test.

Just an FYI, the hazard flasher module tends to become erratic over age. This is due to cold solder joints and I was able to fix mine by re-heating solder connections. Not saying that is the issue, but it could be. Either way, plan to invest in a new one if you are not familiar with soldering procedures or if you don't have the right equipment.