Brake Light Modification for MKIV Golf
Created by schnabba for the TDICLUB.
This is intended to show how to add a second brake light to each side of the standard Golf
IV tail light assembly. We are going to utilize the empty fog light socket to add another
light bulb, and then wire it so that it comes on with the brake lights.
Warning: you are messing with electrical circuits here. Make SURE you use proper rated
wire and connectors. Also, make SURE you insulate them well using heat shrink tubing.
Exposed wiring presents a fire hazard!
Contents:
1.
2.
3.
4.
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6.
7.
Tools you will need
Parts you will need
Making the Jumper Wire
Modify existing tail light assembly
Finished!
Final Notes
Appendix A – circuit diagram for taillight
Tools you will need
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Wire cutter / stripper (or something to cut and strip the insulation off of a wire)
Soldering iron (you don’t need this, but a soldered connection is recommended)
Parts you will need
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Heat shrink tubing
14” of 12 gauge stranded insulated wire
4 female blade connectors (small size blades – the ones for 14 gauge wire work)
Make the Jumper Wire
We will make a jumper wire to connect two terminals on the back of the light assembly. I
used a “grounding pigtail” from home depot, because these are already the correct length,
and are nice 12 gauge wire.
Cut the ends off the grounding pigtail (or cut a length of wire about 7” long.)
Now, strip the ends of the wire
Crimp the ends on the wire, solder them once they are on (we need a good connection
here) and then use the heat shrink tubing to cover the pigtail lead. MAKE SURE the heat
shrink tubing goes up all the way up to the top of the pigtail (see pictures below).
Close- up picture of the pigtail end.
Finished pigtail – shown next to ruler for finished length.
Modify the tail light assembly
Punch out the block off for the fog light on each side. Install bulbs into the assembly
where these block off plates were removed. Use the same bulb as the other brake /
backup lights in the tail light assembly.
Drivers side. We want to connect the jumper from the terminal at the top of the light that
says BR to the RIGHT side terminal that says RF. The BR terminal at the top of the light
is a single contact. This one is easy.
The contact on the lower right (for the driver’s side) is TWO contacts. ONLY jumper the
contact that says RF – this is the OUTSIDE of the two, or the one on the RIGHT as you
look at it. See picture below.
On the right (picture below) we see the top connector, and there is only a single
connector in the receptacle marked BR. The one below on the right, is where we attach
the bottom of the jumper, to the contact marked RF. We see why you need the heat shrink
tubing to keep the jumper from shorting out!
Here is the Passenger side jumper. Again, the top is a single contact (the one that says
BR).
The bottom one is two contacts – and we want to jumper the outside one, or the one
farthest to the left.
Here on the left, we see the top connector – a single connector. Here on the right, we see
the bottom of the jumper, this is on the RF marked connector, to the OUTSIDE of the
passenger side light.
Finished Product (drivers side only shown)
Final Notes
It is also possible to modify the existing harness, there is a wire that is not connected in
the original harness – you can attach the lead to the BR marked wire to the one that is
empty marked RF. NOTE: I have not tested this, only observed that it is possible. I take
no responsibility if you mess something up!
I don’t know part numbers for these connector types – it would be a cleaner installation,
but I haven’t gotten that far yet. The way I have shown is the cheapest.
Below is the empty receptacle in the harness that connects the RF lead on the driver’s
side – if you can tap into the RED/BLACK wire (second from the right), this should
provide power to the circuit when braking NOTE: I have not tested this method yet –
only the jumper wire I have shown in the procedure above).
Also – on the passenger side, the empty receptacle is on the OPPOSITE side of the
assembly.
Appendix A
Here is a circuit diagram for the lights themselves…