Tech Article Title Author Date
B5 DRL Mod michael - stanton 2005
Driving with the lights on during the day has quite a few advantages:
  • You’re more visible even in bad light conditions, e.g. at sunset.
  • Your car can be immediately identified as moving or ready to move. Among others, this allows others to tell a parked car from one that’s waiting at a red traffic light.
There is no need for bikers to worry about their safety: Obviously, cars with DRLs will have no impact on the visibility of motor-cycles on an otherwise empty road due to its headlight. The only difference, though, is that motor-cycles may not stand out from a bunch of cars the way they used to, but I doubt this was the reason why motor-cyclists are required to drive with their light on at all times. Headlights mean that a vehicle is approaching you, so you should watch out regardless of what kind of vehicle it is.

Having added my two cents, let’s get started with the instructions.


How the DRLs Work

I don’t trust the tiny aftermarket DRLs – they are small, low-wattage and easy to overlook. The headlights are definitely better suited for the task. Besides, using your headlights as DRLs will save you the work on the front bumper.

This mod is equal to the factory DRLs in Scandinavian A4s (as well as Canadian ones before 1999.5); only the wiring is slightly different. As a rule, I don’t cut, drill or dremel any stock parts for mods, which allows me to undo all my mods and sell the car as stock.

This is how the DRLs work:

  • When the light switch is in the “off” position, the low beams, city lights (for European-spec A4s)/parking lights (for US-spec A4s), taillights and license plate lights will light up when you turn on the ignition. The instrument cluster stays dark.
  • In the other positions, the light switch works as before.
  • When turning on the high beams, the lows stay on (this was different on my European-spec 1996 A4).
  • You can no longer turn on the parking lights on one side only using the turn signal stalk. You can only turn on the parking lights on both sides at the same time, this is done with the light switch just like before.
Is it legal?

Since you are about to modify the lighting devices of your car, there may be some legal points to consider. The following goes for the E.U. (as well as some other countries, but NOT the U.S.), for which the requirements can be found in the ECE guidelines. ECE-R48 contains regulations on DRLs.
  • The DRLs described here are what the guideline refers to as “reciprocally incorporated lamps” or, in plain English, daytime running lights combined into a single unit with the headlights, which means the headlights must be approved as DRLs. Since all Scandinavian A4s were shipped with this kind of DRLs, all A4 (E-code) headlights should bear the approval sign.
  • Previous versions of the guideline required the taillights and license plate lights to light up with the DRLs. (The new guideline no linger requires this but has not been transformed into E.U. law so far.) The DRL mod complies with the more restrictive old version.
  • No individual approval is necessary in Germany (in other states/countries, your mileage may vary).
  • The factory setup includes a resistor to reduce the brightness of the headlights in DRL mode. I am not sure about the legality of going without the resistor (as described below).
As far as I can tell, this mod should be legal in most of Europe, as well as Russia, Turkey, Australia and Japan. I have no idea about the corresponding DOT guidelines, so if you live in the U.S., you’re on your own. (If you’re in Canada, you don’t need this mod anyway.)

Bottom line: I take no responsibility for the legality of this mod. If you are not sure whether it is legal in your state or country, ask first.

Wiring Diagram

Also available as a PDF document.



Parts Needed

Qty. Part no. Description Price
1 8D0 951 253 A DRL relay (city lights/parking lights and taillights), No. 373 or 214 € 21.11
1 443 951 253 A DRL relay (headlights), No. 209 € 17.23
2 443 937 527 Relay socket € 4.29
2 000 979 212 Cable (2.5 mm²) with 2 relay socket contacts (pins 4, 6)
(4 contacts needed)
€ 1.10
2 000 979 135 Cable (1.0 mm²) with 2 relay socket contacts (pins 2, 5, 8)
(3 contacts needed)
€ 1.10
1 000 979 227 Cable (2.5 mm²) with 2 relay socket contacts (pins 2, 5, 8)
(2 contacts needed)
€ 1.10
1 000 979 225 Cable (2.5 mm²) with 2 relay socket contacts (pins 1, 3, 7, 9)
(1 contact needed)
€ 1.10
1 000 979 133 Cable (1.0 mm²) with 2 fuse socket contacts
(1–2 contacts needed)
€ 1.10
1 000 979 214 Cable (2.5 mm²) with 2 large female round contacts
(2 contacts needed)
€ 1.10
1 000 979 216 Cable (2.5 mm²) with 2 large male round contacts
(1 contacts needed)
€ 1.10
1 000 979 117 Cable (1.0 mm²) with 2 small female round contacts
(2 contacts needed)
€ 1.10
1 000 979 118 Cable (1.0 mm²) with 2 small male round contacts
(2 contacts needed)
€ 1.10

The total price of these parts is € 62.32. In addition, we need some parts from the hardware store:


Description
4 ring contacts for crimping
Electrical wire, 0.5 mm² (colors: brown, black/yellow and yellow/black)
Electrical wire, 1.0 mm² (colors: red, green/red and green/black)
Electrical wire, 2.5 mm² (colors: yellow, yellow/red and white/yellow)
Cable ties
Shrink tube for insulation

The factory DRLs include a resistor to reduce the brightness of the headlights in DRL mode. My dealership was unable to get it, so I left it out, which leaves my headlights burning at full intensity even in DRL mode.

The contacts for the relay sockets, fuse sockets and light switch are not available individually. Audi will sell only short cables with a connector of the desired type at each end. With a little effort you can pry these off the wire and crimp them onto a new one, or you may cut the wire in two and use a method of your choice to extend it.

Preparing for Relay Installation

To get access to the relay holder, remove the diver’s knee bolster as follows:

  • Pry off the fuse cover with a screwdriver.
  • Behind it you will find two of the screws that hold the bolster. Remove them with an 8-mm bit.
  • There are two more screws at the top of the pockets in the bolster; remove them as well. (American A4s don’t have the pockets in the bolster, but the screws should be in the same place, below the steering wheel.)
After that you can pull out the bolster toward you. You’re now looking at the relay holder.

Note the terminals on the underside of the relay holder – we will attach some wires to them later.

It’s easiest to use wires of the same colors as shown in the wiring diagram. Else mark the free ends of the wires (“I’m a red wire”).

The Taillight Relay

This relay is marked with the number 373 (or 214) and will go into slot 8. First you need to prepare the relay socket with contacts and cables.

  • To pin 2 attach a 1.0-mm² cable (red in wiring diagram) with a ring terminal at the far end. (Will be attached to terminal 30, i.e. +12 V, later.)
  • To pin 4 attach a 0.5-mm² cable (brown), also with a ring terminal at the far end. (Will be attached to ground later.)
  • To pin 6 attach a 0.5-mm² cable (black/yellow) with a ring terminal at the far end. (Will be attached to terminal 75X later.)
  • To pin 8 attach a 1.0-mm² cable (green/red) with a free end. (This will become the power supply for the parking lights or city lights, as well as for the taillights and license plate lights.)
After that, you can install the socket into slot 8 of the relay holder and attach the ring terminals to the terminals on the relay holder. There is a ground terminal near the relay holder, to which you can attach the brown wire.

The Headlight Relay

This relay is marked with the number 209 and will go into slot 9. As with the other relay, prepare the socket first.

  • To pin 2 attach a short 0.5-mm² cable (yellow/black) with a free end.
  • To pin 3 attach a 2.5-mm² cable (white/yellow). In a stock setup the resistor would be attached to this pin, with the other end going to pin 2; as we’re going without, we’ll short pins 2 and 3: If you have managed to pry the contact off the cable it came with, crimp the free end of the cable from pin 2 to it; if not, just cut off the existing wire, leaving just a short stub. Attach the free ends from pin 2 and 3 to another 2.5-mm² cable (white/yellow) with a large female round contact at the far end. (Will be attached to pin 1 of the light switch later.)
  • To pin 4 attach a 2.5-mm² cable (yellow/red) with a large female round contact at the far end. (Will be attached to pin 8 of the light switch later.)
  • To pins 5 and 8 attach a 2.5-mm² cable (yellow) that goes from one pin to the other. Tap into it and attach another 2.5-mm² wire (yellow) with a large male round connector. (Will be attached near the light switch and supplies the power for the headlights.)
  • To pin 6 attach a 0.5-mm² cable (brown) with a ring contact at the far end. (Will be attached to ground later.)
Install the socket into slot 9 and attach the ring terminal to the ground terminal near the relay holder.

The Fuse for the License Plate Lights

ECE-R48 requires the electrical connections for the license plate lights to be such that they, the city lights and taillights can only be switched on simultaneously. This makes it necessary to rewire the license plate lights.

  • Open the flap at the back of the fuse box to get access to the back of the sockets. If necessary, remove the two 8-mm screws that hold the fuse box in place.
  • Remove fuse #4 and switch on the headlights. The license plate lights should remain dark.
  • Use a voltage meter to determine the contact in the fuse socket that supplies 12 V (in my case it was the left one when looking at the fuses).
  • Switch off the light and remove that contact: Bend open two paper clips and push them into the socket on both sides of the contact in order to release the notches. Now the contact is free to be pulled out.
  • Cover the free contact with a piece of shrink tube that extends beyond the contact. Bend the free end to the cable and fix it with a cable tie.
  • Install a contact with a 1.0-mm² cable (green/red) into the free socket by simply pushing it in (no need to unlock anything). Attach the other end to the green/red wire from the taillight relay. Add a third 1.0-mm² wire (green/red), which will go to a location near the light switch later.
  • Insert the fuse.
If you fail to pry the contact out of the fuse box (I gave up after trying for an hour), simply relocate the fuse to a free slot. I used slot #10, which is unused in any 1996 A4.

  • Insert the contact with the 1.0-mm² cable (green/red) as the left contact into slot #10 and hook up the other end as described above.
  • Install a second contact into slot 4. Pull the other end through a hole into the fuse box and attach a spade contact that will fit into the fuse slot. Plug it into the right contact of slot 4.
  • Install the fuse into slot 10.
Re-attach the fuse box if you removed the screws and close the flap.

Preparing the Light Switch

First remove some of the steering column covers:
  • Remove the small frame above the steering column - simply tilt it toward you and take it out.
  • Move the steering wheel all the way down and out.
  • There are two recessed Phillips screws at the bottom of the steering column; remove them. There is no need to remove the middle screw.
  • Lift the upper part of the steering column cover at the front and pull it out.
At the left of the steering column you will see the 14-pin connector of the light switch. Pull it off – this may be a little difficult as the connector is difficult to grab; it’s easiest if you use a screwdriver to pry it off. Be careful not to cause a short with the blade!

Now pull the four wires from the relays to the switch. The easiest way to do this is to insert an extra wire at the top, tape the other wires to the bottom end of it and pulling them up by the extra wire.

I recommend zip-tying the four wires to the existing wiring harness.

Prepare four short pieces of 1.0-mm² wire:

  • two with a small female round contact (green/red and green/black) and
  • two with a small male round contact (green/red and green/black).
Attach them to the green/red cable that goes to the taillight relay.

Modifying the Light Switch

The last step is to attach our wiring harness to the light switch. The pins are numbered as follows (when looking at the plug, cables pointing away from you):

14 o o 7
13 o o 6
12 o o 5
11 o o 4
10 O O 3
9 O O 2
8 O O 1
A slide-lock mechanism holds the contacts in place. Move the pink plastic piece up (i.e. away from pin 1) to pull out the contacts.
  • Remove pins 4 and 5 and cover them with a piece of shrink tube. Plug the two small male connectors from our wiring harness into them and slide the shrink tube over the bare metal. Bend each cable into a loop and fix it with a cable tie – this acts as a a strain-relief.
  • Insert the two female round contacts attached to the same cable where we just removed the other contacts.
  • Pull off pin 10 and cover it with a piece of shrink tube. Plug the large male connector into it, slide the shrink tube over it and strain-relieve it as before.
  • Pull off pin 12 and insulate it with a piece of shrink tube.
  • Insert the contact that goes to pin 2/3 of the headlight relay (white/yellow wire) as pin 1.
  • Insert the contact that goes to pin 4 of the headlight relay (yellow/red wire) as pin 8.
Make sure all contacts are pushed all the way in, then close the slide-lock mechanism and attach the plug to the switch again.

If you’re cautious, you might want to check all connections: Are ground pins really grounded? Do the other ones have the correct voltage in all switch positions? Are pins wired to each other where they should be? Are there any shorts?

Testing the Setup

If everything is fine, insert the relays and test the setup:
  • Do the low beams, taillights, license plate lights and parking lights light up when you turn on the ignition?
  • Do the parking lights work as they should (light switch in middle position, both with the ignition on and off)?
  • Can the low beams turned on manually, and when you turn off the ignition, do they turn off while the parking lights stay on? Do the high beams work?
If everything works as expected, put the covers and bolsters back on.




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