[SwissJetPilot]

My new tail light connectors and de-pinning tools have arrived for this little project.

Everything was ordered from Amazon. The pair of connectors and wire/terminals were 12-Euro and came with splice connectors which I won't be using.

The de-pinning tools were about 3-Euro for the set of three. Not the greatest quality, but hopefully it gets the job done.

 

[richydraper]

yay, electrics!

A bit of general info for those that dont know "TE Connectivity"/"Tyco" are the company who make 99% of automotive connectors (Ford, i know, stray away from this logic, probably a few others) all of their plug housings will show a part number usually in this format ######-#, sometimes youll get a manufactures number too (i know Mercedes-Benz do)

Official TE Crimps are anywhere from £70-1000 depending on what youre wanting. (TE Connectivity Cable, Connector & Crimping Tools| RS) most of the dies/jaws are sold seperately. unless youre doing harness manufacture its really not worth the price point. even the depinning tools arent worth the pricepoint (+£50 for the ones suitable for terminals shown above 9-1579007-1 | TE Connectivity Crimp Extraction Tool, AMP Series, Pin Contact, Contact size 2.36mm | RS)

if youre wanting a crimp for these terminals you need something along the lines of ones shaped like these https://www.knipex.com/sites/defaul...default/files/styles/knipex_product_zoom_1_1/public/IM0013785.jpg?itok=D40rg4Jl they crimp the copper and the seal to the terminal in one action when using ratcheting crimps. You can get thinner plier style crimps that will do copper or seal, but not both at the same time, whilst perfectly adequate they tend to bend the terminal which can make it hard to refit into the recepticle.

 

[SwissJetPilot]

@ richydraper - Agreed. I prefer to use quality tools for my projects, but in this case spending a ton of money to replace a single burnt terminal didn't make a lot of sense. Now if I was replacing an entire wiring harness, then the investment in proper tools is a no-brainer.

In this case however, I will be removing the OEM wires from the OEM connector, and installing them into the new connector. I will not include the OEM ground terminal to avoid the possibility of another burnt connector.

At this point the OEM ground wire is redundant anyway, so I will just cut off the damaged terminal, put a bit of tape over the end of the wire, and shove it in the connector just to keep it out of the way.

 

[SwissJetPilot]

Job #1 is removing the pre-installed wire/terminals from the connector. This was a bit fiddly trying to get the de-pinning tool onto the terminal sweet spot, but once you figure out the first two, the rest are pretty easy to do. There's a slight click or thud when the tool hits home which indicates both tangs are now depressed enough to pull the wire/terminal out of the back of the connector. If you have it right, the wire/terminal comes out very easily.

I did run into one terminal which was a real PITA to remove and after it came out, you can see where the tang was bent back on itself. The trick is to let the tool do it's job. If both tangs are correctly depressed, the terminal wire will come out easily. If you're pulling on it and it won't come out, then reposition the tool and try again.

Now if you decide to go with these cheap 1-Euro tools, don't expect too much from them. The metal is soft and the "fingers" can twist and bend which results in them not lining up properly when inserted. One finger will be on one tang, but on the other side it won't be on the tang at all. I suspect this is how I ended up damaging one of the terminals shown below. So check that the fingers are correctly aligned if you can't seem to get the tangs to release.

In this case I was much less concerned with the condition of the wires/terminals than I was in not damaging the connector since this is going to be my replacement.

Next step will be de-pinning the rear light connector, and inserting OEM wire/terminals into the replacement connector. But as I"m running out of daylight, that will have to wait until tomorrow.

Start by sliding pink retaining clip out of the connector. A small jewelers screwdriver works perfectly -

Get the de-pinning tool lined up in the center of the terminal and press it into the connector. Be sure both fingers are on the outside of the terminal and not one finger on the outside and one finger into the terminal itself. There should be a click or thud and then you can try pulling the wire/terminal from the connector. If there's any resistance, remove the tool, reposition it and try again -

When the de-pinning tool is correctly positioned inside the connector, both tangs will be fully depressed. Only then will wire/terminal will come out easily from the connector -

Note the lower terminal has a tang bent over on itself. If you pull the wire/terminal out without the tang fully depressed, this is the result -

Be sure the fingers are not twisted and misaligned or it will only depress one tang and miss the other -

Seems to be a legit VAG part number, but the lack of any VAG logo makes it suspect.

 

[SwissJetPilot]

Now comes the fun part - swapping the OEM connector for the new one.

With the tail light assembly out of the way, I placed a towel into the metal work in case I dropped anything so it didn't disappear into the abyss. Using the de-pinning tool makes it quite easy to remove each wire/terminal from the OEM connector. First, I removed the pink locking clip. Then I removed one of wire/terminals and immediately inserted it into the correct location in the new connector. Do this one-by-one and you are less likely to mix them up. Once all the wire/terminals were seated, I connect the tail light assembly and checked that all the bulbs worked; driving lights, indicators and reverse. Perfect! Not a difficult job at all TBO and I think this took me about 30-minutes.

What was really remarkable was how badly burnt the ground terminal really was inside the connector. As you can see in the close ups, it burnt away the top half of the connector slot. Thankfully the right tail light connector is perfect, so I only had to do this for the left side.

So I think we can call this chapter closed on the Non-OEM rear tail light wiring fix. I didn't expect it to go to this extreme but, whatever. At least it's all working.

Having learned how to de-pin the replacement connector last night, de-pinning the OEM connector was straight forward. Remember to remove the pink locking clip before you attempt to do this.

Wire/terminals were removed one at a time and simply inserted into their same position in the new connector.

I cut the ground terminal off and cut the ground wire back enough that it would stay in the connector with the seal in place, but not make contact with the ground pin in the tail light assembly. This was only done to ensure the connector was sealed since it can get a bit wet and mucky back there.

All the wire/terminals are now properly seated with the ground wire put back just to keep the seal in place and keep the connector sealed. The ground wire seal was pushed in as far as it would go so it has a tight fit around the ground wire. As the non-OEM primary and secondary ground wires make OEM ground wire redundant, there's no point having it in the circuit.

Close up inspection of the damage to the connector and ground terminal is impressive. Looking back at the picture of this same connector when I first did the non-OEM repair, has obviously continued to get worse over time. This makes it quite clear why the Non-OEM primary and secondary ground-wire project may be required if your tail light isn't working like it should.

 

[Jezzie]

Hmm - I expected to see that the ground pin (female side) had lost all its springiness with its legs wide apart. (This starts to feel like I’m writing porn!). But although blackened it looks in good shape - physically - although it’s clearly not going to have a low contact resistance. Well done.
jez

 

[eccles291]

This is all very interesting. 👍🏻 I’ve done the secondary ground wire mod on both rear light clusters, as per the instructions on here, and whilst it solved the problem I now have another issue with the RHS light cluster. With the lights on, the tail light is illuminated but only dimly. If the earth pin in the connector is now redundant having done the mod, what else could be causing the issue?

 

[SwissJetPilot]

@ eccles291 - With mine, it was a bad connection where the upper ground plane (in blue) and lower ground plane (in red) are staked together, one on top of the other, within the rear tail light assembly socket.

Over time corrosion between the surfaces of both ground planes cause problems despite the additional non-OEM ground wire resulting in a bad ground for the entire assembly.

I simply added another ground wire inside the light assembly across both ground planes, and because the connector was so badly damaged, replaced the burned connector and that sorted it. More here -

Left tail light is dimmer than the right one -

Upper ground plane (blue) and lower ground plane (red) are staked together at the connector socket of the tail light assembly -

An internal ground jumper connects the upper ground plane to the lower ground plane. On the outside of the housing, the lower ground plane connector on the left is also the external non-OEM ground wire terminal point as shown below -

From the outside, this is where the non-OEM ground wire is connected and runs into the vehicle to the chassis ground point inside the trunk

 

[eccles291]

Thanks so much SJP! I somehow missed your reply but I will check this out tomorrow in daylight. It sounds like it could sort my issue out, otherwise I'm absolutely at a loss. 🙏 I'll post back once I've taken it off and done the extra mod. (It shouldn't take long as I'm a bloody expert at taking the sodding lights out with the number of times I've had to mess about with them! 🙄😄)

 

[wsantos]

SJP, got in the car today and had a right rear light warning come on but it went off after restarting the car. So I've been reading this thread and found this video which might be useful for people wanting to add the extra grounding wire.

Sent from my SM-G996B using Tapatalk

 

[TT'sRevenge]

Ugh. So yesterday I was working in my garage (on garage stuff not car stuff ha!) and had the cars outside. As it started to turn dark I went to put the cars back in the garage and then I noticed...gasp!

Like happened to SJP I think I have the same thing happen now too--my left rear light is once again dimmer than the right! ‍I did the grounds last year, everthing seemed even and now this. Darn it, gonna have to pull out the light and take a look again😡

 

[wsantos]

Ugh. So yesterday I was working in my garage (on garage stuff not car stuff ha!) and had the cars outside. As it started to turn dark I went to put the cars back in the garage and then I noticed...gasp!

Like happened to SJP I think I have the same thing happen now too--my left rear light is once again dimmer than the right! ‍I did the grounds last year, everthing seemed even and now this. Darn it, gonna have to pull out the light and take a look again[emoji35]

That sucks... Did you get an error code or dash warning? I'm keeping my eyes on mine and, just for reverence, my local Audi specialist quoted £250 to have both done including new connectors, bulbs and back boards, all parts supplied by Audi.

Sent from my SM-G996B using Tapatalk

 

[SwissJetPilot]

Connecting the two internal ground planes is pretty straight forward. Same with re-pinning the connector if it's badly burnt.

 

[Johneve]

Personally, I don't see the point in re-pinning the connector, the problem will just come back.

If you solder a length of wire to both ground planes inside the the lamp unit and then lead it out through the vent hole on the back of the unit (so no holes to drill) taking it on down to the earth stud in the boot you have a sure-fire repair for the total cost of a length of wire.

 

[TT'sRevenge]

That sucks... Did you get an error code or dash warning? I'm keeping my eyes on mine and, just for reverence, my local Audi specialist quoted £250 to have both done including new connectors, bulbs and back boards, all parts supplied by Audi.

No errors or anything for the tails. Never had one before either, I had just noticed one was dimmer before and did the ground mod. Now what I believe is the same side (though I can't remember) is dimmer once again. I mean I only see the possibility of a ground loop (if there's too much resistance between grounds between the sides) but that doesn't really do anything to lights I didn't think...

Connecting the two internal ground planes is pretty straight forward. Same with re-pinning the connector if it's badly burnt.

Did you mean to connect the two grounds to the same point instead of separate ones? I already did the grounding last year but grounded them to their respective ground points on the sides of the car, not both to the same point. Not sure if that helps somehow or if that's even what you're saying.

Personally, I don't see the point in re-pinning the connector, the problem will just come back.

If you solder a length of wire to both ground planes inside the the lamp unit and then lead it out through the vent hole on the back of the unit (so no holes to drill) taking it on down to the earth stud in the boot you have a sure-fire repair for the total cost of a length of wire.

I think most of us have grounded to a ground point in the car though--at least I have. However like SJP I now have the one light dimmer than the other. My car was originally like this, but after doing the ground mod they were even. Just recently (and I know it's just recent 'cause I'm always looking for it to return lol) it has...returned. Again with left side dimmer than the right. However what I didn't do was solder it to the ground plane, I just screwed it in as shown in the DIY. Maybe that nut has come loose or something. I will check it out when I get a chance and solder it this time, repeat on the other side for good measure.

 

[Johneve]

That's the problem with nut and bolt method, you may not get a good, permanent connection. I admit soldering to the ground plane wires takes a 100W or greater soldering iron and a little patience but you do get a certain connection that will last for ever.

 

[tttony]

There are two ground planes in each light unit. Over time the contact between them starts to develop some resistance. Some people soldered a wire between the two planes. However it is easier (and I say better) to drill a hole through both planes where they overlap and put a short self tapping screw through the hole. Somewhere on the forum I posted some pictures of the mod.

 

[TT'sRevenge]

That's the problem with nut and bolt method, you may not get a good, permanent connection. I admit soldering to the ground plane wires takes a 100W or greater soldering iron and a little patience but you do get a certain connection that will last for ever.

100W? Wow that seems like a lot, I have a 50W one but that's the highest. I'm sure can just do the ol' melt the solder and flow it on the nut/terminal though, no? Might not be a perfect or pretty job but should...do the job better than just the screw and terminal.

In any event these damn lights are too darn sensitive!

There are two ground planes in each light unit. Over time the contact between them starts to develop some resistance. Some people soldered a wire between the two planes. However it is easier (and I say better) to drill a hole through both planes where they overlap and put a short self tapping screw through the hole. Somewhere on the forum I posted some pictures of the mod.

Oh right, gotcha. So the ground bars in the single light--connect those together. I'll probably look into pulling the light towards the end of the week. Will let you guys know what I find. Whether that nut loosened, the connector terminal melted up more, or if it's just a matter of joining the bars to fix it...

 

[Johneve]

The ground planes inside the light unit are attached to the plastic case periodically with plastic stubs melted over the metal. You need to choose a spot to solder between the plastic stubs so you can get the metal hot enough without melting the stubs. I used a Weller instant heat 100w soldering gun.

You're right these lamps are just too sensitive. I started by fixing my LHS unit because that was the one that was giving me errors and the earth pin looked a little discoloured but not burnt. Having fixed that one, I tried the lights and it was obvious that the RHS unit was darker than the newly fixed LHS one. The RHS one wasn't giving any errors and its earth pin in the connector looked perfect. I think it was a marginal design from the get go. I then did the same repair to the RHS and had equally bright rear lights and no more errors!

It's also an opportunity to replace all your bulbs with new Osram or similar quality bulbs since even if still working the original factory bulbs will have darkened significantly.

 

[TT'sRevenge]

I think it was a marginal design from the get go.

Oh yeah I think this is 100% for sure. In my mind it's definitely a case of inadequate grounding. One ground wire for all the bulbs and the ground "bus bar" or plane system in the light is not ideal either. If you look at other Audi designs for the same era there is usually one ground wire for the lamp assembly as well except the fact is on most other Audis the light is split--there's a section of light on the bumper and then a section on the trunk/hatch. On the TT it's all one light unit. Cars like A3, A4, A5, Q5, A6, A7...pretty much all of them have the bulbs separated into two housings, each with its electrical connector (and ground). To me it seems like they just applied the same logic of one ground when there are more bulbs; which seem absolutely unfathomable at first but then look at the asinine 1st edition timing chain tensioner on the EA888, lol!

In the words of AVGN...What were they thinking?!?

It's also an opportunity to replace all your bulbs with new Osram or similar quality bulbs since even if still working the original factory bulbs will have darkened significantly.

Yeah all my bulbs are original too, maybe it's time to change them out as well... I've never had any bulb-out errors BTW but clearly the tail lights are messed up on this car model as a whole...