name the mystery land rover part

The item in question is a Lucas Headlamp Dim-Dip unit. It is designed to illuminate the dipped headlamps at a lower intensity than normal when both the sidelights are on and the engine is running. To this end it usually picks up on the sidelights, engine oil pressure switch, headlamp dip and a ign 12v feed. Unfortunatly the electronics in them fails (how unusual for Lucas), and produces a variety of strange results, including a complete failure of dipped headlamps.

They seemed to be a standard fitment between about 1988 and 1991 to UK spec cars, wether this was phased out, a "feature" or the Construction and Use regs changed again I don't know.

As for where you'd get a replacement one, I have no idea. Best suggestion is to remove it. (It's not part of any MOT test) You may need to couple together the dipped headlamp wires (blue-red) on the plug in order for the dips to function with the unit removed.

Alex

Alex, you are a star man. I've been scratching my head for hours trying to work out what it is. The symptoms have been that the dipped headlights are on permanently and the only way to get them to go off is to either take the two fuses out or to disconnect the battery. I suspected this "dim-dip" unit to be at fault because the blue/red had a permanent 12v to it which i suspect is picked up from the brown live. Strangely, now it is disconnected, all the lights work perfectlly going off and on when they should. Am in correct in thinking that this unit can be left disconnected without affecting anything else. I dont want any wiring burning out or anything. I hope this to be the case!

Dave

On or around Sat, 15 Dec 2007 16:33:18 -0800 (PST), Dave R enlightened us thusly:

You should be able to leave it disconnected. Non-UK vehicles will have a short bridge wire between the 2 blue-red wires on the plug.

dim-dip is, I think, no longer compulsory on new vehicles, and you can thank the EU for that, cos it was one of the harmonisation things. Having said that, I find that dim-dip is still in RVLR, see below. There's exemption for vehicles conforming to various EU legislation (type approval, I think) but I'm not sure that allows you to not have dim-dip working on something to which it's fitted. I don't think it's in the MOT, however. Often problems with the dimdip unit are not electronic, but iffy connections or a sticky relay.

The LDV convoy has a clever arrangement of dim-dip which changes the dip beam filaments from parallel wired to series-wired. I can supply a copy of the circuit, if anyone wants :-)

Road Vehicles Lighting Regulations 1989 [excerpt]

PART 1 REQUIREMENTS RELATING TO OBLIGATORY DIMDIP DEVICES AND RUNNING LAMPS

1. A dimdip device fitted to satisfy regulation 18 shall cause light to be emitted from the dippedbeam filament of each obligatory dippedbeam headlamp, each such light having, so far as is practicable, an intensity of between 10 and 20 per cent of the intensity of the normal dipped beam.

1. Running lamps fitted to satisfy regulation 18 shall be in the form of a matched pair of front lamps, each of which :

(a) is fitted in a position in which an obligatory front position lamp may lawfully be fitted, and

(b) is capable of emitting white light to the front having an intensity of not less than 200 candelas, measured from directly in front of the centre of the lamp in a direction parallel to the longitudinal axis of the vehicle, and of not more than 800 candelas in any direction.

1. The electrical connections to the obligatory dimdip device shall be such that the light output specified in paragraph 1 above is automatically emitted whenever the following four conditions are satisfied, namely :

(a) the engine is running, or the key or devices which control the starting or stopping of the engine are in the normal position for when the vehicle is being driven;

(b) the obligatory main beam and dipped beam headlamps are switched off;

(c) any front fog lamp fitted to the vehicle is switched off, and

(d) the obligatory front position lamps are switched on.

1. The electrical connections to the obligatory running lamps shall be such that the light output specified in paragraph 2 above is automatically emitted, whenever the conditions set out in subparagraphs (a), (b) and (c) of paragraph 3 are satisfied.

Dave R Hi,

since you are doing the job may I propose something that we do here in Greece?

Most Defenders over here date from 1989 up to 1991 and they initially were imported and used by the Greek Police. Now most of them have been auctioned by the State as surplus to the requirements of the police and have found their way to private hands.

When we restore them we fit a relay feeding power from the battery or the alternator directly to the lights. The size of the lighting wires was not big enough and the lighting switch was not strong enough to withstand the power of the electricity consumed by the light for long hours or when fitting higher wattage lights or using dim and dip together.

Fitting a relay will save you or your friend from melted wires and damaged switches on your lighting circuit.

Take care Pantelis

What and have the maker pay for repairs under the warranty?... The life of a product should only just exceed the warranty, so the product is still new enough for the owner to think it worth repairing and they have to pay for it at hyped spares prices.

Dave you are absolutely right.

I phrased my wording wrong.

What you said was exactly want I meant.

Take care Pantelis