Head light wiring

[ianmayco68]

Hi all , I’ve upgraded the headlight wiring on the project as in the tech archive and totally removed the dim dip circuit, and I’m left with a blue/red wire out of the indicator stalk . Do I need to connect this to anything or cut it off?

[western]

the blue/red is the dip beam wire, where the dim dip relay was join the 2 blue/red wires together & that allows normal dip headlights to operate.

[ianmayco68]

Well bit of a problem there as that’s the only bit of the dim dip circuit left all the other bits are totally gone .

[western]

On my 300tdi diagram photo attached, the blue/red at column dip switch goes to the passenger compartment fuse box at fuse 22, 10 amp. 

[ianmayco68]

My wiring colours are different to that Ralph , mine are as the 200tdi as in white instead of white/green . But it is an early 300tdi there wasn’t an under seat fuse box but there was a 4 fuse one in the engine bay , I’ll take some pics in the morning but the blue/white and the blue from the column switch and the relay both have two off shoots to the fuses for the lights I think .

Edited April 24, 2021 by ianmayco68

[western]

on the 200tdi then the blue/red has a joint with 2 from under dash fuse box, then goes to the old dim dip unit 5 pin plug, 

Just to left of fuses in diagram below is the 4 way junction of the blue/red wires, bottom line comes from dip switch, the 12 & 3 o'clock lines got to fuses, the 9 o'clock line goes up to connector 8 (top left of the diagram) pin 2 which is for the dim dip unit pre 300tdi type,  if your new wiring is fully functioning then that subject blue/red can be terminated safely. 

Hope that helps. 

[ianmayco68]

I’ll have to look in the morning, what exactly did the dim do ? 

[western]

Dim Dip was a system brought in to help prevent accidents in built up areas where street light was, it illuminates the dip beam filament at about 10% power so the dip is on but not at full power, in an attempt to make the vehicle more visible to pedestrians, the original LR system had a black box transformer like this unit attached.

 

it was very unreliable & when it failed the dip beam couldn't be switched off, only way was to unplug the unit. I had about 7 fail in 20 odd years, so mine is now removed, but wiring is still in place,  IIRC the law for dim dip was challenged by EU & it was repealed.

Quote

from wikipedia ----------- 

Dim-dip lamps[edit]

UK regulations briefly required vehicles first used on or after 1 April 1987 to be equipped with a dim-dip device^[41] or special running lamps, except such vehicles as comply fully with UN Regulation 48 regarding installation of lighting equipment. A dim-dip device operates the low beam headlamps (called "dipped beam" in the UK) at between 10% and 20% of normal low-beam intensity. The running lamps permitted as an alternative to dim-dip were required to emit at least 200 candela straight ahead, and no more than 800 candela in any direction. In practice, most vehicles were equipped with the dim-dip option rather than the running lamps.^[41]

The dim-dip systems were not intended for daytime use as DRLs. Rather, they operated if the engine was running and the driver switched on the parking lamps (called "sidelights" in the UK). Dim-dip was intended to provide a nighttime "town beam" with intensity between that of the parking lamps commonly used at the time by British drivers in city traffic after dark, and dipped (low) beams; the former were considered insufficiently intense to provide improved conspicuity in conditions requiring it, while the latter were considered too glaring for safe use in built-up areas. The UK was the only country to require such dim-dip systems, though vehicles so equipped were sold in other Commonwealth countries with left-hand traffic.^[42]

In 1988, the European Commission successfully prosecuted the UK government in the European Court of Justice, arguing that the UK requirement for dim-dip was illegal under EC directives prohibiting member states from enacting vehicle lighting requirements not contained in pan-European EC directives. As a result, the UK requirement for dim-dip was quashed.^[41] Nevertheless, dim-dip systems remain permitted, and while such systems are not presently as common as they once were, dim-dip functionality was fitted on many new cars well into the 1990s.

 

 

[ianmayco68]

Think I can just cut it , so here’s what I’ve got , from light switch at the stalk ,

blue wire goes to relay ,

the blue wire the goes to the indicator stalk and there’s the blue/white for the main beam and flash ,

the blue/white has three off shoots two to the fuses 13 & 14 and one to the warning light . 

 

the blue has two off shoots one to the rear fog light , obviously so it only works when the lights are on and other goes to the dim dip relay then from the relay to the head light fuses sorted ,

I think the blue/red wire from the indicator stalk is just the trigger wire for the dim dip relay, I think 🤔.

[western]

Yes I think so, that would agree with the wiring diagrams above, 

my dim dip is removed & the 5 wires in its plug are disconnected, it doesn't affect any other system,

[monkie]

The dim dip thing is annoying and in my opinion added unnecessary complication to what should be fairly simple (I understand it used to be a UK requirement). 

This is how I rewired my lighting circuit eliminating traces of the dim/dip stuff... 

Brown live feed to the light switch. Red wire goes to the fuse box for the left and right tail/side lights plus an off shoot going to the "lights on" dash lamp. Blue goes to the dipped/undipped switch on the stalk and also a piece off to power the rear fog switch and fuse (blue/purple up to the fog lamp fuse). 

From the dip/undip stalk switch, blue/red is for the dipped beam to the fuse box. Blue/white is for undipped to the fuse box with a piece off to the dash lights to illuminate the undipped warning lamp 

 

[western]

Quote

 to illuminate the undipped warning lamp

think you mean the blue full/main beam light on dash, there isn't a dip beam warning light, just the green side/tail lights on light. 

[monkie]

Just now, western said:

think you mean the blue full/main beam light on dash, there isn't a dip beam warning light, just the green side/tail lights on light. 

Yes, exactly. Full full/main beam is what I am referring to by undipped.