shauno

Ok, so ya I know, shouldn't have done that but I did....

I spliced into the LED tail light wires for the lights located in the rear hatch on my 2010 Q7, ran wires down to the passenger side fuse location and installed a powered Curt Trailer wire package at the same time I installed my Curt receiver hitch.

It was a last minute job, for along distance drive with the boat trailer (outfitted with LED lighting). I drove over 11hrs with the set up and the lights worked flawlessly besides the error I got immediately into the trip. The LED lights on the boat trailer worked great and the lights on the rear lid still work.....BUT, and the big BUT is....I am getting an error on the dash for the right rear light, right rear brake light and right rear turn signal (funny enough no errors for the left).

When I signal right the signal indicator on the dash flashes fast. However the right rear light works just fine, lights up, brake lights work and signal light flashes at normal speed from the exterior.

I've since completely removed all my spliced connections to the tail lights to try and get this to go away, but it isn't. I can't visually see anything wrong, and everything appears to be working well. I've unplugged the tail light and the control module and plugged them back in, but I still get this warning.

I'm wishing two things...that I had never done this, and that I had a wiring diagram for the tail lights!

Hoping someone may be able to offer some insight? Could I have roasted something? All the fuses I checked in the rear hatch are still good. No wires look burnt or damaged (beyond the splice)

Why would I get a warning for one tail light but not the other when I spliced into both?

Does anyone have a tail light wiring diagram?

I'm thinking that in the end, this is going to end up costing me more $$ then if I had just done it the Audi way to begin with!!!!

I do plan, and promise, to post a resolution as I can't live with 3 warning beeps everytime I start the car and super fast turn signal.

Any help is appreciated.

iconoclast

first things first... scan for codes... go from there.

igotag

EDIT: I misread your post. If you spliced into the factory LED lights in the Q7. Then your resistance would be higher than expected and thus trip a warning.

Ok... Not uncommon. I don't think the errors are related to problems in wiring. LED's have a lower resistance than a normal lightbulb. You will need to install some sort of resistor between the tails and the car. Otherwise the system is going to think your bulbs are blown based on lower than normal resistance. I think this will help you out! https://www.superbrightleds.com/more...istor-kit/190/

shauno

Thanks for the replies.

I will have to get access to a scanner to check that out.

The thing is I've removed everything I spliced in and I am still getting a warning. If it was simply resistance based, wouldn't it see that everything is "normal" again and the warning should have went away, correct?

iconoclast

the codes may have to be scanned and then cleared to remove the MIL. outside of that not much anyone on here can say without knowing codes.

Edd W

I suspect clearing codes may well clear the problem. The logic of the bulb monitoring will probably be different with OEM LED lights than with conventional bulbs. Any failure will probably be for the whole array rather than individual LED's and would not be classed as user replaceable so it would warrant a trip to the dealer. The codes would then be cleared as the new fitting is installed.
You could probably get away with splicing the wiring and using a 7 channel by-pass relay to avoid lowering the resistance of the circuit to a point where it trips the warning.

igotag

So you shouldn't have to clear codes with VAG-COM to get the light warnings to go away. Did you use 'wire taps' to tap into your wires? Those things are notorious for damaging wires. While your lights are actually working, they might be under higher resistance based on damaged wiring from the taps. Your tail lights are probably less sensitive to increased resistance vice the monitoring system in the car with a high and low threshold. Which would in turn flag the light warning.

Double check all your repair work and ensure that everything is perfect. Meaning there are no broken strands inside any of the wire sheaths etc. If the 'light' warning is still on, there is something you missed.

shauno

I did use the wire crimps that splice in and the wires are kinked but still intact. You think the system is that low on threshold to detect a change by a couple broken wire strands?

Should I cut and re splice the wires together to ensure?

I have ordered a vagcom kit to run codes anyways as I wanted one.

I was under the conception that the system should reset itself on checking if all was good....as it has in the past with a burnt headlight and a rear fog lamp. Althought those were bulbs that are replaceable. This is the LED tail light...maybe requires a code reset as it's more then just a bulb?

Will find out sooner or later here.

igotag

In this specific instance I can not definitively tell you yes or no due to: A. Not knowing the high/low resistance settings for the system and B. Not knowing current resistance across the light. I would assume based on everything else Audi does, the tolerances are probably pretty tight.

I can tell you the crimps have given me problems like this in the past. I would work out the kinks and cut out the area that was crimped, re-solder, and heat shrink (assuming you have enough wire to work with). A kink could also lead to a broken strand depending on the bend radius of the wire you are working with.

If you have a fluke you could take resistance readings from the left and right sides across the LEDs and compare your results. They should be the same. If they are you should be able to rule out any resistance problems and move into the VAG world.

pchansen

I'll be curious how this one is resolved. Sometimes these cars are too complicated for their own good. Someone at AOA should have told the Mother Ship that we North Americans love to splice and wire things up like old trailers or change the lights in a trailer or car to LED's.