Thread: Have I fried my headlight switch?

Originally Posted by biggin

When you turn your headlights on you should have power on dashboard fuses 22 and 3 (high beam), or fuses 9 and 10 (low beam).

If no power, check engine compartment fuse link 10. If you haven't burnt out some wiring, this is the likely problem.

I trust you are faultfinding with your new driving lights wiring disconnected.

Affirmative on the driving lights being disconnected.

I just unplugged the Traxide wiring upgrade H4 connectors and put a bulb back into the stock bulb sockets and they work ok - so that should rule out my stock wiring and headlight switch being defective right?

Now I just need to see why the Traxide kit is not playing ball - maybe the relay got fried last night? But why wouldn't the fuses have blown?

Nothing like Auto Electrics 101 on a Saturday morning via a web forum....cheers for your help Biggin.

I'm following this with interest as the strange problem I have my D2 has re-emerged and I'm completely stumped for am answer.

Runs OK until I turn the headlights on and the engine and all power shuts down?????? (No I haven't done it while driving - just in the driveway)

Turn light switch back to parker lights and the power re-energises but all dash lights stay on????

Key off - wait 10 seconds, turn engine back on and all is OK until I try the headlights again and it happens again.......bad earth?? burnt out module?? duff relay???

It's got me beat until I get the car to an auto-elex.......

I don't want to hijack this thread so I'll watch with interst

After an hour on the phone to my old man (ex LR devotee from way back but now drives a Jeep...) I may be closer to a solution.

The relay seems to be working as I can get the headlights to illuminate by running a wire between S1 and S on the relay and the battery terminals.

There is a 3 pin plug with yellow, white and purple wires that runs between the old H4 socket (plugs into it) and the relay. We think that the purple wire may have burnt out. So when the unhappy toddler finally crashes this a/noon I'll head back down to the shed and replace that purple wire to see if it resolves anything.

That sounds ominous. The electrical gremlins are among us! I'm sure someone will have some input soon enough.

Have you got the Traxide wiring upgrade kit in your D2? Otherwise there doesn't appear to be a relay in the headlight circuit for the Discovery. It's switched at the headlight switch straight from the battery - goes through the fuseboxes before it gets to the lights.

RAVE reference pg 85 Electrical Circuit Diagrams >>> EXTERIOR LAMPS >>> Head, Side and Tail Lamps

Originally Posted by Catmatt

I'm following this with interest as the strange problem I have my D2 has re-emerged and I'm completely stumped for am answer.

Runs OK until I turn the headlights on and the engine and all power shuts down?????? (No I haven't done it while driving - just in the driveway)

Turn light switch back to parker lights and the power re-energises but all dash lights stay on????

Key off - wait 10 seconds, turn engine back on and all is OK until I try the headlights again and it happens again.......bad earth?? burnt out module?? duff relay???

It's got me beat until I get the car to an auto-elex.......

I don't want to hijack this thread so I'll watch with interst

Catmatt, it really sounds like your battery is shagged.Low voltage will trigger all sorts of stuff. A cheap check and easy fix.

Hi Bell1975, I have only just gone through my PMs.

First off, if the other end of the cable you dropped was connected to the “B” terminal on the relay, nothing should have happened, unless the relay itself is faulty.

Did you wire up the driving light relay when you originally wired up the headlight relay or have you just installed the driving light relay.

The Purple wire is connected to your head lights common terminal and this does control whether the relays work or not.

In the case of Land Rover head lights, as their headlight common is negative at all times, you may have had a dead short and damaged the purple wire.

Try removing the purple from both relays and then connecting the “S” terminal on your HEADLIGHT relay only, to earth.

If your headlight then work, you may have a damaged/faulty driving light relay.

See how you go with the test and we can go from there.

Thanks Tim, the headlight relay was fitted on its own for a few months and I added the driving light relay into the mix a couple of days ago.

I reckon Murphy was an auto electrician as I don't do a heap of night/pre-dawn driving but this week I have a few journeys on the highway in the early/late hours so I thought I'd wire up the relay and put some LED spots I have on loan onto the vehicle to test....now I am back to stock Disco lights until I can get it sorted. One step forward but 3 steps back.

My Dad has assisted with troubleshooting this over the phone as he knows far more about auto electrics than I ever want to.

His suggestion was that the purple wire was probably cactus. I checked the continuity of it while it was in situ and got readings that suggested 'faulty'. When I removed it from the vehicle and checked it again it was fine.

I'll be able to have a look at it tomorrow or Tuesday and I'll post back with the outcome.

Cheers Tim.

Originally Posted by drivesafe

Hi Beel1975,.