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Model specific boards => Golf mk4 => Golf mk4 how to guides + info => Topic started by: GregUK on 26 June 2009, 17:23
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This guide will take you through the steps involved in replacing coil pack wiring which has become cracked or damaged due to heat exposure. The instructions will guide you through cutting the new and old wiring, and splicing them together using spade connectors. As an alternative, the wiring could be soldered, but I chose to use connectors for simplicity and ease of removal should the need arise.
Note: This guide is provided for a 1.8T AUM, but should be the same or similar for other engines. Please check that the new part matches your old wiring before cutting anything.
Cost: <£30
Time: 2 hours
Difficulty: Easy to Moderate
You will need:
- Coil pack wiring harness adapter - VW part number 1J0 971 658 M (1J0971658M)
- Wire cutters
- Utility knife
- Flat screwdriver
- Small adjustable spanner
- Multimeter (optional)
- Spade connectors:
- 0.4 to 1mm male (6)
- 0.4 to 1mm female (6)
- 1.1 to 2.6mm male (5)
- 1.1 to 2.6mm female (5)
(http://i574.photobucket.com/albums/ss185/gregbolshaw/01.jpg)
- Silicone tape (3 metre roll). The one I used is tested to 250 degrees.
(http://i574.photobucket.com/albums/ss185/gregbolshaw/02.jpg)
- Medium zip-tie (1)
Instructions
1) Disconnect the car battery by unhooking the negative terminal.
2) Remove the main engine cover, then remove the three-way PCV pipe, pictured here:
(http://i574.photobucket.com/albums/ss185/gregbolshaw/03.jpg)
3) Unplug the cables from each of the four coil packs.
4) Unbolt the coil pack earth cable which is next to coil pack 1. Put the bolt back in place for safe keeping.
5) Using a screwdriver, prise the small black tray that the coil pack wiring sits on away from the engine.
The coil pack wiring will now be free. You will see where it enters into a plastic pipe as it disappears down the right-hand-side of the engine.
6) Use a screwdriver to unlatch and remove the clip that is holding the end of this plastic pipe together.
7) With your hand, follow the plastic pipe around 20cm down the right-hand-side of the engine where you will find an identical clip. Leave this one connected to the plastic pipe, but pull its fixing away from the engine to gain a bit of extra freedom.
8) Starting at the top, begin to remove the wiring from the plastic pipe.
Before continuing, count the wires: there should be 11.
9) Identify at which point the insulation of the wiring ceases to be cracked. Using the wire cutters, cut each of the wires at this point. Remove the old coil pack wiring from the car.
10) Cut the surplus plastic pipe so that the shortest wire protrudes by around 5cm.
11) Fit a zip-tie to secure the end of the plastic pipe, in lieu of the plastic clip which was removed in step 6.
12) Strip approximately 5mm from the end of each wire and twist the ends.
You should now be at a point that resembles this (although I hadn't cut the plastic pipe or twisted the ends for this photo):
(http://i574.photobucket.com/albums/ss185/gregbolshaw/04.jpg)
13) Crimp four of the female 1.1-2.6mm spade connectors onto each of the thick purple/black wires, and a further one onto the thick brown wire.
14) Crimp six of the female 0.4-1.0mm spade connectors onto each of the remaining wires.
That's the car-side of things done. Note that one of my wires had to be cut considerably shorter due to the extent of the insulation damage.
(http://i574.photobucket.com/albums/ss185/gregbolshaw/05.jpg)
15) Unbox the replacement wiring harness.
(http://i574.photobucket.com/albums/ss185/gregbolshaw/06.jpg)
16) Remove the first two clips that hold the plastic pipe together, remove the wires from the pipe, and cut the wires at the point indicated.
(http://i574.photobucket.com/albums/ss185/gregbolshaw/07.jpg)
(http://i574.photobucket.com/albums/ss185/gregbolshaw/08.jpg)
17) Crimp spade connectors onto the new wiring as per steps 13 and 14, only using male connectors.
(http://i574.photobucket.com/albums/ss185/gregbolshaw/09.jpg)
18) Match and connect the new wiring to the old.
N.B.
- It doesn't matter which of the black/purple wires you connect to which - they all terminate at a common point.
- There are three wires which are all the same colour brown. The way to tell them apart is by their thickness.
- The four important wires are the striped thin ones - these control the firing order. They do tend to fade, so if in doubt, refer to the wiring removed in step 9 to match the old and new wires correctly.
(http://i574.photobucket.com/albums/ss185/gregbolshaw/10.jpg)
19) Using 5cm strips of silicone tape, individually wrap each spade connector joint to cover all exposed metal. Stretch the silicone tape as you wrap it.
20) Continuity testing (optional). Using a multimeter, check to ensure that pins 1, 2 and 4 have continuity across all four plugs. There is no way to verify pin 3.
21) Using larger strips of silicone tape, wrap all of the individual wires into one bundle. Start in the middle where the spade connectors are and work downwards towards the plastic piping (overlapping this slightly). Then from the spade connectors upwards towards where the black tape finishes near plug number 4. Again, stretch the silicone tape as you wrap it.
22) Mount the new small black tray that the coil pack wiring sits on onto the engine.
23) Attach the coil pack earth cable to the bolt on the engine.
24) Plug the cables into each of the four coil packs.
25) Push any excess coil pack wiring down the right-hand-side of the engine.
26) Re-fit the three-way PCV pipe removed in step 2 and re-fit the engine cover
27) Re-connect the car battery.
Job done!
(http://i574.photobucket.com/albums/ss185/gregbolshaw/11.jpg)
Please let me know how you get on, or if you have any feedback to help me improve this guide.
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Those wires look like they need covering/braiding or something :) Excellent write up though.
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Those wires look like they need covering/braiding or something :) Excellent write up though.
Thanks.
Yes, I am surprised that VW only use a small piece of plastic to protect the wiring. The whole thing should come mounted to a metal heat shield!
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It'd be useful to see a picture of our old cable
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It'd be useful to see a picture of our old cable
Yeah, sorry for the lack of "before" photos. I dissected the old cable during the making of this guide :smiley:
This give you an idea of how badly damaged the old wiring can be though:
(http://www.ecstuning.com/stage/images/dis/7867/800/crackedcoilharness.jpg)
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Did it make a difference? or sort your missfire?
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Did it make a difference? or sort your missfire?
Yes, this made a massive difference - 3 weeks on and no more misfiring. Now I just need to solve my 17705 boost leak. It's one problem after another with these Mk4s!
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Good guide there Greg!
Before you all get excited and go buying the wiring harness, count the wires. Access the ignition loom leading off the R/H side of head, strip back plastic shield and count the wires (the ones Greg cut). I believe this is somehow related to whether you have an oil level sensor or not?
10 Wires, buy the "658L" type harness (no oil level sensor on sump)
11 wires buy the "658M" harness (oil level sensor on sump)
I should have counted them 1st! I c0cked up and bought L instead of M! :grin:
Another guide here on VWVortex: http://forums.vwvortex.com/zerothread?id=2597240
ps - for another £20 get the Audi TT heat shield, protects all your hard work and tidies it all up! :wink:
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Before you all get excited and go buying the wiring harness, count the wires. Access the ignition loom leading off the R/H side of head, strip back plastic shield and count the wires (the ones Greg cut). I believe this is somehow related to whether you have an oil level sensor or not?
10 Wires, buy the "658L" type harness (no oil level sensor on sump)
11 wires buy the "658M" harness (oil level sensor on sump)
I originally ordered the 'L' by mistake too. This seemed to be for LHD models as the wiring exits the coilpacks to the left rather than the right; the colours of the signal wires are also reversed (4-3-2-1). Fortunately, I hadn't cut mine, so VW agreed to swap it for the 'M'. I'm pretty sure the 'L' had 9 wires though, not 10. It was just missing the two brown wires which are for the oil level sensor.
My car is a Y-reg 2001 AUM and had 11 wires. The 'M' part was the correct part for my car. How many wires do you have and what colour are they?
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The 658L harness I bought (below) is the same orientation with cables exiting away to the n/side. Wiring from the connectors all the same sequence and colours too, it's just short of a small brown wire for the oil level sensor:
(http://i713.photobucket.com/albums/ww140/najmeade/P7020002.jpg)
VW swapped it for the "M" type in the end! :smiley:
If considering doing this work, there's a 4 week wait for these!!!
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Phew all done! What a job. I decided to solder the wiring (bit like this http://www.teamnovak.com/tech_info/how_to/solder/index.html) and then heat-wrapped each exposed joint.
Car seems a lot smoother with improvement to the flat-spot issue at lower revs. Couple of images here with the Audi heat-shield fitted:
(http://i713.photobucket.com/albums/ww140/najmeade/OverlayHarness.jpg)
(http://i713.photobucket.com/albums/ww140/najmeade/OverlayHarnessb.jpg)
2nd image - I extended the shield over the end of the head by salvaging part of a heat-shield off the new harness :wink:
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Fancy doing mine then!?
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Fancy doing mine then!?
I wouldn't do mine again now! :tongue:
Nah, it was simple enough, just a bit daunting, time consuming and very fiddly. The spade connector method would be quicker, but not convinced the connection integrity would remain in that environment.
Whichever way it needs to be shielded afterwards or it'll happen all over again!
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Am I missing something? Would it not just be easier to replace the whole harness out, rather than cutting it up?
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Am I missing something? Would it not just be easier to replace the whole harness out, rather than cutting it up?
You only cut it in one place and replace with a standard VW part, or it can be fitted into existing connectors if you have the skills.
Replace the whole harness? A complete new harness would be silly moneys....
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I only mean the part of the harness bought - the part you see in the photo :smiley:
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I only mean the part of the harness bought - the part you see in the photo :smiley:
You can but it means re-routing the harness through the fire wall and over the place, and re-wring existing connectors. There's a proper guide somewhere or other.... https://wiki.bentleypublishers.com/download/attachments/2130569/vw.tb.97-04-02.pdf?version=1
Its up to you how you do it, but just wanted to make the point that you can! :wink:
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any ones got the pics for this...........?!
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any ones got the pics for this...........?!
I aint got pics. It sounds a bit daunting but its pretty straight forward.
Cut the coil pack wires off down the side of the block and re-attach (solder or connectors) to the appropriate section cut from the repair loom. See the second image I posted showing extra heat-shield bit? I contained all the wiring joints within the ribbed cable tidy coming out to the right of the heat wrap.
I did the wires one at a time, but it would be quicker and just as easy to cut the lot off in one go. It'd be neater too as I had to recut and adjust the length of a couple as I went. I'd recommend staggering the lengths slightly to avoid possibility of any shorting if your insulation fails.
You can wire the repair harness into existing plugs etc without chopping wires, but that is a big big job. There's a VW technical service bulletin for doing that: http://www.audizine.com/forum/showthread.php/293531-Coil-Pack-Wiring-Harness-Replacement-1.8T
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Sorry for reviving a dead thread guys but does anyone happen to have a copy of this guide saved anywhere with the pictures? Doing this tomorrow and would like visual reference!
Thanks and sorry for bringing back the dead!