Mk3 Headlights FAQ

[The Other Simon]

[Moved to FAQ section by Trev16v]

A selection of stuff on the Mk3 headlights.

The headlights, sidelights and foglights are completely separate systems, that are all wired through the headlight switch. Which it is such a weak point in the system.

Pinouts of the Mk3 headlight switch:

Pin Name Wire Colour Function

1 58b Grey/BlueFeed to the Dimmed Dashboard Illumination
2 56White/Black Headlights
3 56D YellowFeed to the dim/dip system (UK only)
4 XrGrey/BluePower via the foglight fuse
5 XzBlack/Yellow Power via the ignition switch (unfused)
6 58R Grey/RedSide and Tail lights (Right)
7 58Grey/GreenNumber plate (and feed to US foglight relay)
8not connected
931Brown&nbs p;* ;* Earth
10 SRA Yellow/Blue Feed to headlight wash/wipe system
11 30Red/YellowPermanent Power (unfused)
12 NSL Grey/WhiteRear fog lights
13 NLGrey/Yellow Front fog lights
14 58L Grey/BlackSide and Tail lights (Left)
15 TFL not connected (US daytime running lights, uses yellow wire)

Pin 4 provides the power for the foglights (pins 12, 13)
Pin 5 provides the power for the headlights (pins 2, 3, 10)
Pin 11 provides the power for the sidelight system (pins 1, 6, 7, 14) Pin 9 is the earth for the interior illumination dimmer (pin 1)


The headlights are wired:
Battery
Ignition Switch
Headlight Switch
Indicator Column Stalk (splits into high/low beams)
Fuses (splits into left/right)
Headlights
Earth

The sidelights are wired:
Battery
Headlight Switch (splits into left/right)
Fuses
Front and Rear lights
Earth

The foglights are wired (in the UK)
Battery
Fuse
Headlight Switch (splits into front/rear)
Foglights
Earth

The foglights are wired through relay position 10, using a metal jumper (823-941-817A) to link pins 3 and 4.

The headlamp flasher (pull back on the indicator stalk) is a completely separate system, with a permanent live feed going direct to the indicator stalk, bypassing the headlight switch.



There are three part numbers for headlight switches:
1H6 941 531AH is for vehicles with rear fogs only
1H6 941 531AJ for vehicles with front and rear fogs.
1H6 941 531F for vehicles with front and rear fogs and headlight level control.

Contrary to what you might have heard, the AH variant will drive front fogs - if you pull out the switch halfway it will turn on the front fogs only. The drawback is that there isn't a notch to keep the switch half pulled out, nor a light to tell you that the front fogs are on.



If you want to upgrade your CL or GL to use the twin chambered headlights that the GTis and VR6s use, then you need a metal link to keep the low beams on when you switch to high beams (it's an MOT fail if you don't). The metal link needs to join pins 2 and 6 in relay position 10 (where the foglight jumper is fitted). You can make your own link out of some small spade terminals and a piece of wire.
Edited by: Trev16v