MKIV Golf: Fixing Hatch Boot Wiring

MKIV Golf Tech Write-up: Fixing Hatch Boot Wiring

As we know, the Golf is plagued by sub par wiring running from the trunk space to the rear hatch that runs through the boots. Many have fixed the issue, it's not rocket science, but it took a while to get everything together so I figured I'd do a tech write-up to help anyone out in the future.
Originally I wanted to just purchase new boots, but I fell short in being able to find a standalone boot. Also, no one in the US seemed to have a "kit" that included the boot with a section of wires either.
So I went to Ebay and stumbled upon a kit that came from Latvia. I had to wait a while for it to get here, but it included most* of the wiring that you need for the project. The only thing I needed to purchase was some 14ga silicone wiring for the larger OEM wires as the kit provided 16 ga. There's a bit of current running to the rear de-fogger and I didn't want to risk anything melting.
The kits are shown below:
Driver side (Includes the new hose section for the wiper):

and passenger:

The kits include silicone wire. This is key. My recommendation is not to run the common PVC coated wiring that you find at most auto stores. Save yourself from ever having to do this again and purchase silicone wire. It's as flexible as a wet noodle and there are a bunch of very find copper strands. You do not run the risk of it cracking if you use this.
Also I would grab some heat shrink solder butt connectors. I almost venture to say that these are the next best thing since the zip tie:

I also had a trim removal kit shown below. These are handy if you don't want to damage anything, but you could use a solid screwdriver as well:

First thing to do is pop the hatch and remove the 1ea screw in each handle:

I opted to start at the corners and pop the trim towards the middle. They are held in place my metal clips which are held to the trim by plastic. Terrible design because these can break (It looked like a few had been broken by the last person who had removed this trim.

The corners of the trim is guided into the side trim (tan) by a slot. Once you get all the clips undone, the trim will just pull straight down:





When you get to this point, the whole thing will slide down. You can see the gap all around:



And the holder clips (one side shown):



Next is the real PITA...the hatch side trim (tan). There are two knobs that hold the cargo cover to the trim. These need to pop off. But...there is a center piece that needs to slide out before you can pull the whole thing out...it acts as an "expander" to keep the knob in place:



You can see I've pulled the center piece out a little bit. This has to come all the way out then you can pop the bigger piece out of the trim:



Once those are out, just work your way down prying and the side trim will snap off. Do this for both sides and work your way towards the 3rd brake light:

Then the center section of trim needs to come down that's holding the headliner. It also just snaps in place:



Now go ahead and look around, take pictures, and note how the harness is routed:

Passenger side hatch:



Driver side hatch:



Time to start unplugging things to buy some room to move the harness around. I started on the driver side, this will be the more complicated side.
Remove the third brake light plug. It's small so be careful:



Lift the defogger connector out of the white snap in harness guide, and unplug the defogger wire from the black rectangular connector. It's just a spade connection here:



Remove the white snap in guide from the door, noting the orientation. You can slide the harness and wires between each split of the snap in guide:



Remove the connector at the washer mechanism and pop the washer hose off its connector:

Remove the connector at the locking mechanism. It orients a specific way with the release tab so note how that comes out:



Now you can unclip the driver side of the wiring harness. The other thing I did was use painters tape to tape the black defogger connector to the rest of the harness, because you are going to have to pull the harness into a "no man's land" zone in the door for wiring, and when you're done, you want it to come back with the harness so it can sit back in your white guide clip. If you don't tape it to the harness, since the wire is by itself, you risk making this job more complicated trying to fish it out of that "area". Do this to both drivers and passengers side:



Lets move to the inside of the trunk area and pop the trim off there. I opted not to remove the lower storage area (that houses your amp if you have one) since I was not replacing the entire harness. I figured I could unclip enough to get my hands in there to free the harness if I needed to.

Prying back reveals the driver side connectors. Feel free to release this if you need to pull some more harness from the trunk side, but I actually didn't need to do this. Plus my hands wouldn't get down there:



Release the harness clips if you'd like:



Now it's time to cut your boot and reveal what may or may not be a mess.

Drivers side after I had cut all the connections and fluid hose:



Passenger side prior to cutting the wiring. You can see my previous repair had failed at the brown earth wire for the defogger, again...:+

Now there are 3 gauges of wire that VW used in this section of the harness. The larger wire is 14 ga, the medium wire is 18/20 ga, and the small wire is 22ga. If you use the kit that I showed at the beginning, all the wires you will need are there except the 14ga. I would recommend purchasing some silicone wire and using that instead of the 16ga the kit provides, especially since it needs to be able to handle more than 25 A (fuse size).

If you don't get that kit, you'll need to purchase the appropriate sized silicone wire. I bought some 18 and 20ga just for backup wire if I needed it.

I won't tell you how to wire it, but I can offer some tips. You're going to want to feed the hatch side wiring down through the hole to buy yourself room on that side. This is where you can gain the most room to work. The trunk side wiring, you'll want to pull as much out as you can until it stops. You can't buy a lot of room here. I recommend wiring the trunk space side of the harness, shown below, fist:



The goal at the end of the wiring at this stage is when you push the trunk side wiring back into the car, all of your connections will be INSIDE and not in the boot...as shown in the photo again. Also, label your wires as you make your connections if the colors don't match up. Don't forget to splice in some new tubing for the washer fluid line

Once you get 1 side done (like the photo shows above) slide the boot over in place, and wire the hatch side. You should have plenty of room to wire this side since you can slide a lot of the hatch harness through the door to work.

You can then pull the driver side wiring back through and reconnect and run your harness. Test to make sure everything works before you button it back up.

Repeat this same process for the passenger side, it will be a lot easier since there aren't as many wires.

Once again, the keys to this wiring, is once all of your connectors are made and things are in place, they are inside of the trunk area and hatch area (ie none are in the boot). You only want the silicone wire in the boots. Before

Once it's all wired, install your boots and repeat the process for installing all the trim again:





There you have it, you should never have any central electronic, lock, or defogger issues for the life of the car due to the hatch wiring. Saves a lot of money vs. buying and running a new harness!

Very well done, pictures and all.
I started worrying about the wires going into the doors and rear hatch on my 03 Jetta wagon.
More the doors as I ran heavier speaker wires direct to the speakers.
I had a bad feeling once I messed with it the insulation might crack or break off.

Great write-up! Thanks for the details on trim removal, that's what I have

the most trouble with. Those damn clips are a real pain if you don't know where they are, or how they work. Should be stickied!

Rrusse11 said:

Great write-up! Thanks for the details on trim removal, that's what I have

the most trouble with. Those damn clips are a real pain if you don't know where they are, or how they work. Should be stickied!

Click to expand...

Thank you! And yeah those clips are a pain...the previous owner showed the proof of that!

Yes, great job on the write-up!


One additional thing to do is to tape up all the wires anywhere along their flex points. This is more important for any of the original wire as the breakdown of the insulation is going to come sooner with it than with the newer, spliced wire. I did this on my car because I'd bought a used harness and then found out the insulation was brittle! I decided to just wrap up all the wires so that insulation breaks wouldn't result in shorts. Yes, the wire itself is still aged and has gone through lots of bending and is likely to break at some point, but at the time I repaired my car I had to get it done NOW (splicing around wasn't really possible). My repair has held up for 5 years now: past my warranty period

Thanx for the write-up; timing couldn't be better. I have the new harness ready to install that I bought from an on-line dealer. 1J6 971 147 P for the left side harness. I'm waiting for warmer weather since I don't have a garage. Your write-up is more detailed than the u-tube video I had watched.

UhOh said:

Yes, great job on the write-up!


One additional thing to do is to tape up all the wires anywhere along their flex points. This is more important for any of the original wire as the breakdown of the insulation is going to come sooner with it than with the newer, spliced wire. I did this on my car because I'd bought a used harness and then found out the insulation was brittle! I decided to just wrap up all the wires so that insulation breaks wouldn't result in shorts. Yes, the wire itself is still aged and has gone through lots of bending and is likely to break at some point, but at the time I repaired my car I had to get it done NOW (splicing around wasn't really possible). My repair has held up for 5 years now: past my warranty period

Click to expand...

Yeah that's a good point. I looked at the original harness while I was doing work and there's really no points that "flex" other than those wires in the boots. I suppose if we go beyond what this write-up covers, then this would be an issue in any of the door flex points. But as far as the rear hatch harness and in the trunk area, the wiring is pretty solidly tied down, it's not moving. With the new spliced wire I used (silicone) I didn't tape any of the wires to each other or anything, just left them all loose in the boot. It gives everything in the boot a bit more flexibility. As long as none of your splices/connections end up in the boot, you're good to go. I was stoked on how flexible that silicone wire is. Should never have an issue with the back end of this car again.

JB05 said:

Thanx for the write-up; timing couldn't be better. I have the new harness ready to install that I bought from an on-line dealer. 1J6 971 147 P for the left side harness. I'm waiting for warmer weather since I don't have a garage. Your write-up is more detailed than the u-tube video I had watched.

Click to expand...

I probably watched a couple of the same videos but yeah I wanted a bit more detail for people. If you're replacing the harness though my suggestion (which I mentioned in the write-up but didn't do) is you're going to need to remove the storage compartment housing (lower black piece). There's 3 bolts that hold it in place to the trunk side piece trim. You'll need more room then I had to get those connections un-done unless you have small hands. Good luck with your repair!

KrashDH said:

I didn't tape any of the wires to each other or anything, just left them all loose in the boot.

Click to expand...

I taped them independently, not together. The reason, as I was intending, is that when I opened things up I found one broken wire and several with cracked and, in some cases, missing insulation. I figured that by wrapping up each wire that that would keep the old insulation from parting from the wire and leading to a short. It's held up for 5 years; will it hold up for 10 more years? Time will tell


It's interesting that it almost always seems to occur on the left side of the hatch (when facing toward the car). I'm sure that if one spent enough time analyzing this that one could identify the reason for this (and add in a bit of corrective measure): too LITTLE or too MUCH wire could both lead to this situation.

UhOh said:

I taped them independently, not together. The reason, as I was intending, is that when I opened things up I found one broken wire and several with cracked and, in some cases, missing insulation. I figured that by wrapping up each wire that that would keep the old insulation from parting from the wire and leading to a short. It's held up for 5 years; will it hold up for 10 more years? Time will tell


It's interesting that it almost always seems to occur on the left side of the hatch (when facing toward the car). I'm sure that if one spent enough time analyzing this that one could identify the reason for this (and add in a bit of corrective measure): too LITTLE or too MUCH wire could both lead to this situation.

Click to expand...

Yeah that makes sense for a bandaid. The first repair I did was in a parkinglot in the dark on a road trip to Montana...it was a combo of wire nuts and hastily twisting wire together and electrical tape. The second time I used all the heat shrink solder connections, but they were in the boot. 3rd time was the permanent fix.

The passenger side is what made me do this for the final time. I had the larger earth wire (brown) for the rear defroster break on me twice. I was driving to work one morning, headlights on, and noticed my defroster wasn't turned on but the light was orange instead of red. I hardly noticed it, but once you're in tune with your vehicle you notice the smallest things. That caught my eye. It would turn brighter orange if I pressed the button on, and more dim if it was off. Though it was the actual button, so I replaced that. same thing. Tore the boot off the back and found the broken earth wire. So that's the key, if, when your headlights are on and your defogger button is orange, you have a broken earth wire in that mess.

It makes sense the driver side would normally be the culprit though, there are a lot more wires stuffed in there so you lose some flexibility. I had a lot of cracked insulation on that side and only 1 broken wire when I did the original repair.

@KrashDH do you happen to have a link to this repair kit on ebay or know the name of the listing? I was trying to find it to no avail.

@Dhawk12

Left:

Right:

But honestly, I think the rubber is the same. I wouldn't worry too much about the wires that go through them, but the left one comes with an extension of wiper fluid hose which you'll need

I’ve run into a problem… I’ve cut the washer fluid line and the connector that comes in that kit doesn’t fit. Also, the original line is hard plastic and won’t accept the correct size connector. I’m extremely frustrated. I went out and bought various size adapters and nothing seems to be working. I’m now stuck with a broken line that will squirt fluid inside my panels if I hit the washer switch on accident

MrFahrenheit99 said:

I’ve run into a problem… I’ve cut the washer fluid line and the connector that comes in that kit doesn’t fit. Also, the original line is hard plastic and won’t accept the correct size connector. I’m extremely frustrated. I went out and bought various size adapters and nothing seems to be working. I’m now stuck with a broken line that will squirt fluid inside my panels if I hit the washer switch on accident

Click to expand...

Did you buy the same kit I posted? If so it comes with flexible rubber...it should form over/around the existing hard tube. Try heating the hose that came with the kit a little bit to soften it up. Also, there is silicone hose you can buy (Amazon, etc) you can purchase that's very flexible. Just measure the OD of the hard plastic tube and get the appropriate ID silicone hose. You should not need any adapters.

KrashDH said:

Did you buy the same kit I posted? If so it comes with flexible rubber...it should form over/around the existing hard tube. Try heating the hose that came with the kit a little bit to soften it up. Also, there is silicone hose you can buy (Amazon, etc) you can purchase that's very flexible. Just measure the OD of the hard plastic tube and get the appropriate ID silicone hose. You should not need any adapters.

Click to expand...

Thanks Krash!
Yes, I bought the kit from Latvia and some extra 14g silicone wiring for the defroster. The washer hose came with fittings, but didn’t think to remove them and just slide the hose over the hard plastic line. Thanks for the tip!

*EDIT* Since posting below, I found the source of all those problems. My dome lamp fuse was blown causing ALL those issues mentioned. A few wires did work themselves out, but it was just the third brake light and the boot cargo light.


Update: I “fixed” the wiring a few weeks ago, and a few days after the repair, I’m assuming some of the wire worked themselves out of their butt connectors. I’ve lost power door locks, power windows, interior lights, heated mirrors, third brake light, and my car won’t lock even manually (it just unlocks itself automatically). There must also be a parasitic draw because my dash cam is running 24/7 and my battery went flat after I left for a week.
I’m pretty spent with trying to fix it. Does anyone know a good VW shop in LA that may be able to patch this up for me? It’s proving to be more than I can handle

MrFahrenheit99 said:

Update: I “fixed” the wiring a few weeks ago, and a few days after the repair, I’m assuming some of the wire worked themselves out of their butt connectors. I’ve lost power door locks, power windows, interior lights, heated mirrors, third brake light, and my car won’t lock even manually (it just unlocks itself automatically). There must also be a parasitic draw because my dash cam is running 24/7 and my battery went flat after I left for a week.
I’m pretty spent with trying to fix it. Does anyone know a good VW shop in LA that may be able to patch this up for me? It’s proving to be more than I can handle

Click to expand...

I haven't had an issue since doing this fix, it's too bad yours isn't working currently. First thing I'd do is pull the boots back and just look for a wire to see if something came out of your splice. I really had to "pull" on the OEM harness to expose as much as possible out through the metal then make the connections, so when it went back "in" to the body I was sure there were no heat shrink connectors sticking out "into" the boot.

If one of your connections ended up in the boot though, all is not lost, it'll just be a bit more difficult. You've done the hard part once. You'll need to at least pull the side panel in the rear and maybe drop some of the headliner. Then you can make the connections back where the harness is straight and you can run silicone wire from there, through the boot, and to a straight section of the harness in the hatch. Then you're guaranteed that no connections will be in the boot and with that flexible silicone wiring, you can tie that stuff in knots all day without having to worry about it fatiguing and breaking/cracking.

Hello.

I just want to say a big thank you to the OP for creating this thread and also to everyone else that chimed in with tips/suggestions.

My rear wiper had recently started randomly turning itself on, and searching the web and this site for the cause led me to this thread. I had noticed the driver's side hatch boot was breaking on the hatch end, and I could see some of the insulation on the wires was starting to get holes, so I suspected there was a short causing the wiper to run. I ordered the kits listed in this thread (since I wasn't sure what functions ran though which boot) , plus some extra 14ga silicon wire and heat shrink solder butt connectors as recommended. Over the weekend I took a stab at it.

The driver's side was much worse than I realized:




Yikes! I'm surprised I hadn't blown a fuse or something! Passenger side wasn't nearly as bad, but still was in need of repair:



I wasn't brave enough to cut all the wires at once, and when I first started a lot of the smaller wires all looked the same to me. I was rather worried I'd get some mixed up, so I spliced both ends of each wire one at a time. In-progress pic of the drivers side repairs:



I saved the worst two (green and white) for last. I did as recommended and used some of the 14 gauge wire I'd bought instead of the included white wire (or brown in the case of the passenger side).

Passenger's side complete:.



I tested all the functions except defrost before putting it all back together. I'm not sure hot to test defrost until winter, but everything else seems to work just fine. I definitely understand a lot more about how the hatch is wired then before I started, and you all saved me a bunch of $$!

However, I could not for the life of me get the center pin to budge on the two knobs that hold the cargo cover to the trim. I don't know how you all managed to. I tried every method I could think of, but I ended up breaking the round base on both of them while trying to get the center pin to move even a tiny bit. It doesn't look as bad as I though it would, and I guess that's one way to remove the trim.



Maybe one day I'll try to replace them if I can find a source of replacements. But it's still functional, so probably not a high priority.

domboy said:

Hello.

I just want to say a big thank you to the OP for creating this thread and also to everyone else that chimed in with tips/suggestions.

My rear wiper had recently started randomly turning itself on, and searching the web and this site for the cause led me to this thread. I had noticed the driver's side hatch boot was breaking on the hatch end, and I could see some of the insulation on the wires was starting to get holes, so I suspected there was a short causing the wiper to run. I ordered the kits listed in this thread (since I wasn't sure what functions ran though which boot) , plus some extra 14ga silicon wire and heat shrink solder butt connectors as recommended. Over the weekend I took a stab at it.

The driver's side was much worse than I realized:

Yikes! I'm surprised I hadn't blown a fuse or something! Passenger side wasn't nearly as bad, but still was in need of repair:

I wasn't brave enough to cut all the wires at once, and when I first started a lot of the smaller wires all looked the same to me. I was rather worried I'd get some mixed up, so I spliced both ends of each wire one at a time. In-progress pic of the drivers side repairs:

I saved the worst two (green and white) for last. I did as recommended and used some of the 14 gauge wire I'd bought instead of the included white wire (or brown in the case of the passenger side).

Passenger's side complete:.

I tested all the functions except defrost before putting it all back together. I'm not sure hot to test defrost until winter, but everything else seems to work just fine. I definitely understand a lot more about how the hatch is wired then before I started, and you all saved me a bunch of $$!

However, I could not for the life of me get the center pin to budge on the two knobs that hold the cargo cover to the trim. I don't know how you all managed to. I tried every method I could think of, but I ended up breaking the round base on both of them while trying to get the center pin to move even a tiny bit. It doesn't look as bad as I though it would, and I guess that's one way to remove the trim.

Maybe one day I'll try to replace them if I can find a source of replacements. But it's still functional, so probably not a high priority.

Click to expand...

Nice work on the repair!

I think I mentioned it in this thread, but I can't remember. I knew my defrost wasn't working because the LED color was off from the rest of the backlighting. It was orange all the time instead of red. So normally, when the defrost is working properly, when you push the button, the LED backlighting turns from red to orange. It's on a self-timer, so when the defrost is done, the LED turns back to red. So you can technically test it before winter. With your headlights on (so all the LEDs in the car are light up) the defrost LED should be red. When you push it to activate the defrost, it should turn orange. Once the self-timer is done, the LED will turn back to red.

You should be able to feel the warmth of the window when it's on as well. Another trick you might be able to try as long as it's not too hot outside is pressing ice cube up against the window with the defrost button activated.

KrashDH said:

Nice work on the repair!

I think I mentioned it in this thread, but I can't remember. I knew my defrost wasn't working because the LED color was off from the rest of the backlighting. It was orange all the time instead of red. So normally, when the defrost is working properly, when you push the button, the LED backlighting turns from red to orange. It's on a self-timer, so when the defrost is done, the LED turns back to red. So you can technically test it before winter. With your headlights on (so all the LEDs in the car are light up) the defrost LED should be red. When you push it to activate the defrost, it should turn orange. Once the self-timer is done, the LED will turn back to red.

You should be able to feel the warmth of the window when it's on as well. Another trick you might be able to try as long as it's not too hot outside is pressing ice cube up against the window with the defrost button activated.

Click to expand...

Well I'll be darn, I don't know if I ever noticed that color change between red and orange. Great suggestion! And thanks for responding! I'll double-check it, as it'd be nice to know BEFORE winter if I need to get back in there and re-do any of the repair. Thanks again for all your help!

Greetings and warm thank you’d to all for the detailed instruction with pics to *boot*; I have an ‘07 GTI 2dr frnht.ed and purchased a left side harness off eBay — it’s used but it’s in incredibly good shape, and my plan was to add liquid electric tape as well as dielectric grease to nooks and cranny’s and letting it set up for a few days before doing this project, however began to pull preliminary trim.
now I know that this is MKIV y’all are talking about, but I have to ask here because it’s the best and most recent thread on the subject.

. I am stuck at the high center mount brake lamp - stock led-
But how am I supposed to unhook it?



any help is very much appreciated.

First off, many thanks for the instructions. They were very helpful. I ended up splicing in new wires using solder/heatshrink rather than getting the boot kits. One of my boots is torn slightly, but I think I will just live with it. I ended up disassembling the LHS panelling more than you show. This allows access to the release the wiring in the C-pillar, and actually pull the harness fully out of the car body to make working on it easier. The washer hose has quick disconnects at the top of the C-pillar also that can be released by rotating or removing a collar on them. Assuming the washer hose looks to be in good condition, this makes it possible to re-use it and run it through the new boot and might be preferable to splicing it.

I couldn't find any disconnects inside the car on the RHS. The wires appear to cross over the roof under some metal panelling. On the RHS I ended up pulling them further into the car and out another access hole to get the splice further inside the body and then re-running the wires. I ended up cutting RHS wires all at once before realizing that there were two small brown wires. I traced them to the lock tumbler. Does anyone know if the polarity of these matter?

(edited since I mixed up my LHS / RHS. Should be correct now)

Brown is ground. If the car side wires both have continuity to ground at all times, it shouldn’t matter how you connect them. But if the ground is switched on and off to control whatever they go to, you’ll have to figure out which goes to what.

(apologies, my previous post mixed up LHS and RHS, should be fixed now).

I went back and took a closer look. One of the small RHS wires is solid brown, the other brown with a black stripe, it's just very hard to tell with poor lighting and black tape residue. I think the small solid brown is spliced into the larger solid brown for the defrost and both get grounded to the body on a bolt under the LHS C pillar panel. While I didn't do a full continuity check, it looks like the RHS green, blue and brown+black stripe cross to the LHS under the headliner and and some metal panelling and go to the tan coloured disconnect under the LHS C pillar panel, so that might be an option to get more slack on the RHS. Still no idea what the wires to the lock tumbler are supposed to do, some sort of key in lock sensor?

On the LHS it really is not too much more work to fully extract the harness, and then you can work on it on a bench in comfort. I removed a few more panels in the back and loosened the upper LHS C pillar panel a bit more by removing the two nuts holding it along its bottom. This opens up enough access to get to those connectors. The washer hose can be separated by rotating or removing the black collar that sits on the grey connections. If you do this, you can fully reuse the washer hose without any splicing. Fully removing the C pillar panel would require removing the seat belt, and there is a weird clip above the seat belt that is released by using pliers to pull a metal clip toward the rear. Going that far to fully removing it is not necessary though.

A bit more of the c-pillar exposed:

Washer hose disconnect: