After reading a few posts on this topic and not seeing any how-to's, I thought that I would make my own. It is not the same caliber as some other how-to's I have seen here, but hopefully it will help someone. =)
Disclaimers: I did this on a 2002 VW Golf TDI (4 door). Your car may not be exactly the same. I cannot be held responsible for differences in wiring, mistakes in this write-up, things that may get broken while working on this, etc. If you are concerned that you will not be able to do this, DON'T DO IT.
Some background: the logic that controls the hatch on the Golf is strange. You can only unlock the hatch, it automatically locks when you close it, etc. I wanted the hatch to lock when the doors lock and unlock when the doors unlock. Basically, I want it to be a fifth door.
So, I did some digging. There is one motor that controls the locking of the hatch inside the hatch. I thought I would mention this because my Haynes manual indicated that there are two motors (the joys of Haynes). Also, there is a small switch inside the hatch that tells the Central Convenience Module (CCM) that the hatch is closed. This switch is also responsible for turning on the light in the luggage compartment and the alarm function. I initially tried disconnecting this switch, but all that does is make it so that the light does not come on. In addition, there is no way to lock the hatch! So, I reconnected it.
Now to the juicy part. What I did was cut the two power wires for the hatch unlock at the CCM and wired them into the driver's door module. Why the driver's door? Well, I did not want to run wires very far, and the driver's footwell is pretty easy to remove. Another member suggested taking apart the C pillar and doing essentially the same thing. This would work pretty much the same way but I think you need more wire and I have not yet removed the C pillar (whereas I have worked around the dash quite a bit).
Tools and supplies needed:
Phillips screw driver
Flat blade screw driver
Torx bit driver (do not remember size)
Soldering iron
Wire cutters/strippers
Knife
Solder
Two wires about 1 meter (3 ft) long each. I used blue and green because that is the color of the wires that run the hatch motor, but any color would work.
Electrical tape
Flashlight
Multimeter
Time: 1-2 hours
1) The first thing to do is remove the door skin. Pop out the window switch assembly by carefully prying it up. Remove three phillips screws under/behind the switch assembly. Remove two torx screws at the bottom of the door skin. Pop the door skin off using a flat tool such as a screwdriver. Carefully disconnect all wires leading to the skin and lay it aside.
2) Locate the pass-through tube for the door wiring harness. It is a black rubber tube-thing at the front of the door. Pop this out by pulling it.
3) Pry the convoluted rubber harness protector free from the door. Note: this is difficult to pry out.
4) Remove the hood release handle by prying behind it with a screwdriver.
5) Remove the panel surrounding the hood release.
6) Remove three torx screws securing the black dust panel under the dash. Remove the panel by pulling down and toward the front of the car.
7) Now you should have a clear shot at putting the wires through the convoluted rubber harness protector. Run the wires one at at time through the rubber pass-through tube in the door, the convoluted rubber harness protector, and the fender. The fender hole has a white plastic grommet here in the picture. Make sure you do not have them twisted or pinched and that there is plenty of excess at each end.
8) Look up under the dash and locate the CCM. It is a black box secured on a metal bracket above the relay panel. Locate the two wires that control the hatch motor. In my case, these wires were SOLID GREEN and SOLID BLUE.
Be careful here not to cut the wrong wires as the CCM controls many things. If you have any doubts at all, get a multimeter and measure voltage from one pin to the other as you push the hatch release. If these are the hatch pins, when you press the hatch release there will be +12VDC when it opens and -12VDC when it closes or vice versa. I want to mention caution again, as there is a green wire with a brown tracer and other wires that look pretty similar. Note: once you cut these wires you will need to finish the job as the hatch will no longer open except manually (with the key).
9) Strip and solder the ends of the wires you ran through the fender to the two wires you just cut (not the ends going to the CCM, the ones coming from the hatch). This is a difficult spot to reach, but it can be made much easier by removing the gauge cluster (only two more torx screws). In my opinion, it is imperative that these connections are soldered. If you just twist them together, there is a likelihood that they will come loose over time and no longer work. Once these are soldered, be sure to cover them with electrical tape or heat shrink tube. You do not need a short to ground here. =0
10) Using a knife, carefully cut the cloth harness inside the door apart. I did this right above the speaker. Locate the two wires that control the door lock motor. In my car, these wires were LILAC WITH YELLOW TRACER and BLUE WITH YELLOW TRACER. If you have any doubts, use the multimeter to check voltages as you lock and unlock the doors.
11) Strip away about 2 cm (.75 inch) of insulation from each of these wires. Be careful not to cut the wires themselves; cut the insulation at an angle, not straight down.
12) Before soldering this end of the wires, have a helper test the direction of the locking function. The system works by reversing the 12VDC signal, so when you press "lock" one wire is + and when you press "unlock" that same wire is - (the polarity switches). Make sure that the hatch locks when your doors lock. In my case, I connected the SOLID BLUE hatch wire to the BLUE WITH YELLOW TRACER door wire and the SOLID GREEN hatch wire to the LILAC WITH YELLOW TRACER door wire.
13) Once again, solder the connections and properly insulate them with electrical tape (or equivalent).
14) Make one last check to ensure that everything works as you intend.
15) Coil up any extra wire and tie it under the dash or inside the door. I left it in place in case I need to do repairs in the future. Make sure there is enough slack for the wire to move as the door is opened and closed.
16) Replace lower dash panel, footwell panel, gauge cluster (if removed), convoluted rubber harness protector, rubber door tube, and door skin.
17) Enjoy! =)
Notes: The reason that I have modified the wiring like this is that this is fairly easy to do and it is also easy to remove if the next owner wants to. There are a few drawbacks to this method, listed below.
A) The "hatch open" button on the driver's door no longer works. Not an issue for me, as the hatch is now just a fifth door.
B) The "hatch open" button on the remote no longer works. Same as above.
C) The current draw for the driver's door motor circuit is higher. Since I wired the hatch motor in parallel with the driver's door motor, the circuit will draw more current. I am not concerned about this at this point as the circuit has not blown a fuse. I do not foresee this becoming a problem in the future.
D) I should have taken more pictures!
Josh
Disclaimers: I did this on a 2002 VW Golf TDI (4 door). Your car may not be exactly the same. I cannot be held responsible for differences in wiring, mistakes in this write-up, things that may get broken while working on this, etc. If you are concerned that you will not be able to do this, DON'T DO IT.
Some background: the logic that controls the hatch on the Golf is strange. You can only unlock the hatch, it automatically locks when you close it, etc. I wanted the hatch to lock when the doors lock and unlock when the doors unlock. Basically, I want it to be a fifth door.
So, I did some digging. There is one motor that controls the locking of the hatch inside the hatch. I thought I would mention this because my Haynes manual indicated that there are two motors (the joys of Haynes). Also, there is a small switch inside the hatch that tells the Central Convenience Module (CCM) that the hatch is closed. This switch is also responsible for turning on the light in the luggage compartment and the alarm function. I initially tried disconnecting this switch, but all that does is make it so that the light does not come on. In addition, there is no way to lock the hatch! So, I reconnected it.
Now to the juicy part. What I did was cut the two power wires for the hatch unlock at the CCM and wired them into the driver's door module. Why the driver's door? Well, I did not want to run wires very far, and the driver's footwell is pretty easy to remove. Another member suggested taking apart the C pillar and doing essentially the same thing. This would work pretty much the same way but I think you need more wire and I have not yet removed the C pillar (whereas I have worked around the dash quite a bit).
Tools and supplies needed:
Phillips screw driver
Flat blade screw driver
Torx bit driver (do not remember size)
Soldering iron
Wire cutters/strippers
Knife
Solder
Two wires about 1 meter (3 ft) long each. I used blue and green because that is the color of the wires that run the hatch motor, but any color would work.
Electrical tape
Flashlight
Multimeter
Time: 1-2 hours
1) The first thing to do is remove the door skin. Pop out the window switch assembly by carefully prying it up. Remove three phillips screws under/behind the switch assembly. Remove two torx screws at the bottom of the door skin. Pop the door skin off using a flat tool such as a screwdriver. Carefully disconnect all wires leading to the skin and lay it aside.
2) Locate the pass-through tube for the door wiring harness. It is a black rubber tube-thing at the front of the door. Pop this out by pulling it.
3) Pry the convoluted rubber harness protector free from the door. Note: this is difficult to pry out.
4) Remove the hood release handle by prying behind it with a screwdriver.
5) Remove the panel surrounding the hood release.
6) Remove three torx screws securing the black dust panel under the dash. Remove the panel by pulling down and toward the front of the car.
7) Now you should have a clear shot at putting the wires through the convoluted rubber harness protector. Run the wires one at at time through the rubber pass-through tube in the door, the convoluted rubber harness protector, and the fender. The fender hole has a white plastic grommet here in the picture. Make sure you do not have them twisted or pinched and that there is plenty of excess at each end.
8) Look up under the dash and locate the CCM. It is a black box secured on a metal bracket above the relay panel. Locate the two wires that control the hatch motor. In my case, these wires were SOLID GREEN and SOLID BLUE.
Be careful here not to cut the wrong wires as the CCM controls many things. If you have any doubts at all, get a multimeter and measure voltage from one pin to the other as you push the hatch release. If these are the hatch pins, when you press the hatch release there will be +12VDC when it opens and -12VDC when it closes or vice versa. I want to mention caution again, as there is a green wire with a brown tracer and other wires that look pretty similar. Note: once you cut these wires you will need to finish the job as the hatch will no longer open except manually (with the key).
9) Strip and solder the ends of the wires you ran through the fender to the two wires you just cut (not the ends going to the CCM, the ones coming from the hatch). This is a difficult spot to reach, but it can be made much easier by removing the gauge cluster (only two more torx screws). In my opinion, it is imperative that these connections are soldered. If you just twist them together, there is a likelihood that they will come loose over time and no longer work. Once these are soldered, be sure to cover them with electrical tape or heat shrink tube. You do not need a short to ground here. =0
10) Using a knife, carefully cut the cloth harness inside the door apart. I did this right above the speaker. Locate the two wires that control the door lock motor. In my car, these wires were LILAC WITH YELLOW TRACER and BLUE WITH YELLOW TRACER. If you have any doubts, use the multimeter to check voltages as you lock and unlock the doors.
11) Strip away about 2 cm (.75 inch) of insulation from each of these wires. Be careful not to cut the wires themselves; cut the insulation at an angle, not straight down.
12) Before soldering this end of the wires, have a helper test the direction of the locking function. The system works by reversing the 12VDC signal, so when you press "lock" one wire is + and when you press "unlock" that same wire is - (the polarity switches). Make sure that the hatch locks when your doors lock. In my case, I connected the SOLID BLUE hatch wire to the BLUE WITH YELLOW TRACER door wire and the SOLID GREEN hatch wire to the LILAC WITH YELLOW TRACER door wire.
13) Once again, solder the connections and properly insulate them with electrical tape (or equivalent).
14) Make one last check to ensure that everything works as you intend.
15) Coil up any extra wire and tie it under the dash or inside the door. I left it in place in case I need to do repairs in the future. Make sure there is enough slack for the wire to move as the door is opened and closed.
16) Replace lower dash panel, footwell panel, gauge cluster (if removed), convoluted rubber harness protector, rubber door tube, and door skin.
17) Enjoy! =)
Notes: The reason that I have modified the wiring like this is that this is fairly easy to do and it is also easy to remove if the next owner wants to. There are a few drawbacks to this method, listed below.
A) The "hatch open" button on the driver's door no longer works. Not an issue for me, as the hatch is now just a fifth door.
B) The "hatch open" button on the remote no longer works. Same as above.
C) The current draw for the driver's door motor circuit is higher. Since I wired the hatch motor in parallel with the driver's door motor, the circuit will draw more current. I am not concerned about this at this point as the circuit has not blown a fuse. I do not foresee this becoming a problem in the future.
D) I should have taken more pictures!
Josh
