crazy brake and reverse lights

**p07503p** · 03-22-2014 09:36 AM

I drive a 02 avant and my brake lights don't go on in the taillights but work on the light on top of the trunk. Also, for those who are not familiar with the avant brake lights they illuminate when breaking and then are on and dim when driving. So they stay on but don't illuminate when I brake which is weird because that means it's not the bulbs. Also when I throw it in reverse, only the passenger side goes on for a second then blinks repeatedly. I thought it was the bulb holders so I got another set and still have the same problem. Any input is appreciated!

**customa4** · 03-22-2014 09:45 AM

Do you have bulb out errors on the cluster?

**p07503p** · 03-22-2014 09:50 AM

Yeah I do, but the bulbs are good.

**customa4** · 03-22-2014 09:56 AM

Did you check the harness at the taillights for broken wires?

**p07503p** · 03-22-2014 10:02 AM

The wire harness looked in tact when I was changing the tail lights but I didn't really examine them fully

**customa4** · 03-22-2014 10:07 AM

I would get a good look at those wires. Maybe even try to pull back on the rubber surrounding a bit if you can. Don't get too crazy though. Did you make sure all of the bulbs are hitting good contacts. I had a similar problem with my front blinker recently and one of the contacts in the headlight was kinda bent in too far. I used a little hook and pulled it out a little bit and the blinker has been working good since. (Fingers crossed)

**p07503p** · 03-22-2014 10:22 AM

I think the problem might be in the harness but what surprises me is that the bulbs go on but when I brake they don't illuminate.

**Myst420** · 03-22-2014 10:43 AM

Originally Posted by p07503p

I drive a 02 avant and my brake lights don't go on in the taillights but work on the light on top of the trunk. Also, for those who are not familiar with the avant brake lights they illuminate when breaking and then are on and dim when driving. So they stay on but don't illuminate when I brake which is weird because that means it's not the bulbs.

Since the top light works, you know its not your switch. The bulb can be bad even though your taillights work. Have you tried new bulbs just for the hell of it?

Pretty much all cars work that way when it comes to how taillights function, not just avants.

Originally Posted by p07503p

I think the problem might be in the harness but what surprises me is that the bulbs go on but when I brake they don't illuminate.

That's because they are dual-element bulbs, with separate wires for each element. The problem is most likely (as mentioned) in your wiring harnesses somewhere.

**p07503p** · 03-22-2014 10:55 AM

Im gonna check out the harness when I get home and see what I find. Thanks for the help

**customa4** · 03-22-2014 11:35 AM

Are they new bulbs? One fucntion can still work while the other doesn't. It's just odd that you're having problems with more then one bulb at the same time.

**rich045** · 03-22-2014 11:37 AM

i think in every car, the bulbs illuminate brighter when you step on the brakes, not only the avants

**p07503p** · 03-22-2014 11:42 AM

Idk I thought some cars have separate brake lights.

**p07503p** · 03-22-2014 11:44 AM

Originally Posted by customa4

Are they new bulbs? One fucntion can still work while the other doesn't. It's just odd that you're having problems with more then one bulb at the same time.

they aren't new but they are working ones

**Myst420** · 03-22-2014 11:46 AM

Originally Posted by p07503p

they aren't new but they are working ones

How do you know they are working bulbs? have you tried them in another car?

**p07503p** · 03-22-2014 11:51 AM

Originally Posted by Myst420

How do you know they are working bulbs? have you tried them in another car?

I've tried them on different spots of the taillight

**Myst420** · 03-22-2014 11:53 AM

Yes, but they are dual element bulbs, one element can still be bad even though bulb lights up.

**p07503p** · 03-22-2014 12:03 PM

Originally Posted by Myst420

Yes, but they are dual element bulbs, one element can still be bad even though bulb lights up.

you are right. But I still don't know what happened to the reverse lights

**p07503p** · 03-24-2014 01:56 PM

So I tried brand new bulbs and still have the same problem. Checked the wire harnesses and they are perfectly fine too. Any other ideas? ??

**NAFT** · 03-24-2014 02:17 PM

Did you visually inspect them or meter them out for continuity? I've seen some bad coil pack harness that looked just fine until we took the multimeter to them.

**walky_talky20** · 03-24-2014 02:24 PM

Step 1: Get a wiring diagram
Step 2: Check for power and ground
Step 3: Find out what is missing
Step 4: Fix it

Are you 100% certain that you have the CORRECT bulbs in every position? Some are single filament. Some are dual filament. You cannot swap crap around without minding these facts. If you are not sure what single/dual filament means, you need to get professional help.

**Myst420** · 03-24-2014 02:25 PM

Originally Posted by walky_talky20

Step 1: Get a wiring diagram
Step 2: Check for power and ground

Step 3: Enjoy not being rear-ended.

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**walky_talky20** · 03-24-2014 02:26 PM

^lol.

**diagnosticator** · 03-24-2014 02:29 PM

If the reverse light on one side is flashing, the only cause for this is a defective Central Electric Control Module. Since the module is faulty, that is also most likely why the brake lights are not working right. The CECM powers and controls all of the exterior lights. there are no fuses.

**p07503p** · 03-24-2014 02:45 PM

Originally Posted by diagnosticator

If the reverse light on one side is flashing, the only cause for this is a defective Central Electric Control Module. Since the module is faulty, that is also most likely why the brake lights are not working right. The CECM powers and controls all of the exterior lights. there are no fuses.

Ok do you know where is the cecm located on a b6 avant? This thing has been killing me

**Myst420** · 03-24-2014 02:46 PM

It's under the carpet right in front of the drivers seat.

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**p07503p** · 03-24-2014 02:47 PM

Originally Posted by walky_talky20

Step 1: Get a wiring diagram
Step 2: Check for power and ground
Step 3: Find out what is missing
Step 4: Fix it

Are you 100% certain that you have the CORRECT bulbs in every position? Some are single filament. Some are dual filament. You cannot swap crap around without minding these facts. If you are not sure what single/dual filament means, you need to get professional help.

I've tried brand new dual element bulbs and still the same problem.

**diagnosticator** · 03-24-2014 03:15 PM

Originally Posted by p07503p

Ok do you know where is the cecm located on a b6 avant? This thing has been killing me

It is located under the horizontal row of relays, under the drive's side dash, inboard of the fuse panel. FWIW, my CECM failed the same way with flashing backup lights, but no other problems. Since all of the lighting control functions in the CECM are microprocessor controlled solid state transistor switches, turning the lights on and off, each module failure is always somehow different from any other. The high mount brake light, is on a separate circuit from the two tail light brake lights, that is why that is the only brake light working.

**diagnosticator** · 03-24-2014 03:19 PM

Originally Posted by Myst420

It's under the carpet right in front of the drivers seat.

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No, that is the central convenience module, not the CECM.

**p07503p** · 03-24-2014 03:22 PM

Originally Posted by diagnosticator

It is located under the horizontal row of relays, under the drive's side dash, inboard of the fuse panel. FWIW, my CECM failed the same way with flashing backup lights, but no other problems. Since all of the lighting control functions in the CECM are microprocessor controlled solid state transistor switches, turning the lights on and off, each module failure is always somehow different from any other.

Thanks alot! So I need a new cecm? Opinions on getting a used one?

**p07503p** · 03-24-2014 04:00 PM

this is the module we are talking ablout correct?

**diagnosticator** · 03-24-2014 05:05 PM

Originally Posted by p07503p

this is the module we are talking ablout correct?

No that doesn't look right. that does not look like a B6 under dash, where did you get that pic?

**diagnosticator** · 03-24-2014 05:13 PM

This is the CECM, it is mounted upside down. The bottom aluminum cover is facing up.

A good used replacement is the only practical way to go. The most recent version is an "F" suffix.

**p07503p** · 03-24-2014 05:14 PM

Originally Posted by diagnosticator

No that doesn't look right. that does not look like a B6 under dash, where did you get that pic?

i took this picture. i took out the piece under the steering wheel and this was the module on the side of the fuse box

**p07503p** · 03-24-2014 05:18 PM

Originally Posted by diagnosticator

This is the CECM, it is mounted upside down in a mounting bracket. The bottom aluminum cover is facing up.

its the same piece. i saw the part number and its the same. would you think a used one would work?

**diagnosticator** · 03-24-2014 05:35 PM

Originally Posted by p07503p

its the same piece. i saw the part number and its the same. would you think a used one would work?

I recommend buying a good used replacement. New CECMs are prohibitively expensive. If you get a replacement used from a sedan, the module must be recoded to enable the rear wiper and rear window washer. Besides the exterior lights, the CECM powers the windshield wipers and horns, and washer pumps.

If you can only find a module from a sedan, PM me and I will explain the details about recoding the module.

**p07503p** · 03-24-2014 05:47 PM

Originally Posted by diagnosticator

I recommend buying a good used replacement. New CECMs are prohibitively expensive. If you get a replacement used from a sedan, the module must be recoded to enable the rear wiper and rear window washer. Besides the exterior lights, the CECM powers the windshield wipers and horns, and washer pumps.

how would i recode it? the dealer? thanks again for all your help. is it possible that this going bad is the reason my rear driver side window doesnt work??

**diagnosticator** · 03-24-2014 05:51 PM

Originally Posted by p07503p

how would i recode it? the dealer? thanks again for all your help. is it possible that this going bad is the reason my rear driver side window doesnt work??

You will need to use VCDS to recode the module, or have an indy audi shop (or the dealer,) do it for you. The CECM does not have anything to do with the power windows.