Headlights - No dipped beam - except in tandem with the main beam

[ELMA 0]

Hello all - Newbie here . . 

Today had a run out, previously all good but somehow I have lost the dipped headlights. They do come on with the main beam. Other symptoms are the small indicator light on the rocker switch goes out when the switch is advanced from side lights to headlights and there is no blue indicator light on the dash when the main beam is on . . . . It appears I have the uprated wiring loom as yellow plug which I assume is the "dim-dip" resistor is NOT connected. . . . is this likely a simple relay failure ?

[fendervg 32]

I think I saw this on FB if you posted there too - dim dip resistor disconnected is correct if you have an uprated loom. Could be a relay failure, most decent looms keep the OEM plugs intact (if not they will use spade connectors), so you could try bypassing it by connecting the original loom back in - one plug (usually drivers side) should just be sitting loose and unconnected in the bay, and the other on the passenger side will be connected to the new loom to control the relays.

If the relays and fuses are not in a water tight sealed box, they can get wet or corrode.

[ELMA 0]

Yup am reaching out across both medium - The yellow dim-dip connector is disconnected - Am trying to find a simple key to the relays / layout so I can check the relevant ones as the handbook and wiring diagramme manuals are impossible to fathom . . 

[Dox 23]

The relays will be the same, switch them around to prove your theory?

Get someone to operate the switches whilst touching the relays to feel for the click

Edited 11 hours ago by Dox

[Dox 23]

You can use a 9v tv remote type battery to test a relay in conjunction with a multimeter, the pins spacing on the battery means you don’t need wires


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[fendervg 32]

As above - great diagram. The current coming in  from the headlight switch (this will be the old main beam cable, which is one of the reasons why these are needed as the current goes through the stalk and the headlight switch) will open the relay to send current direct from the battery to the headlight.

Will 9v be enough to trigger the relay?

[Dox 23]

20 minutes ago, fendervg said:

As above - great diagram. The current coming in  from the headlight switch (this will be the old main beam cable, which is one of the reasons why these are needed as the current goes through the stalk and the headlight switch) will open the relay to send current direct from the battery to the headlight.

Will 9v be enough to trigger the relay?

Yes, give it a go. I built my first MK2 loom and didn't know which pin did what, 9v clicked the relay and I built it around that.

 

85 / 86 close the contacts 30 - 87, let there be light