Thread: '09 Headlight High Beam stopped working but Low Beam working ok - What the?

Thanks Daz.....

Sounds reasonable but for it to be a short and NOT blow any fuses is a bit strange. I know when I only had ONE bulb in (ie LHS bulb in) and checked the plug on the RHS, I found that ALL 3 Terminals (pins) had 12volt supply on them. With both Bulbs out I had 12v on both the RHS and LHS plugs on the "EARTH" pins (Pins on the RHS of plug) only and the other 2 pins had no volts.
Now, for there to be a short and NOT blow fuses there MUST be some sort of resistance (ie:load) to prevent the fuse from blowing....

I'll have a look for any sort of rubbing but there's not a lot of space to see the wires under the bonnet of a puma.... It
s just strange that with nothing been touched on the car that between times of driving it at night that this has popped it's head up..... very confusing

Originally Posted by DazzaTD5

With everything off, there should be no power to any pins.
*When you look at the plug, as how you have the picture, the centre one is low beam, the high beam is the left one and the earth is the right one.
*see my pic.
*different coloured plug, wiring different colour, i woudlnt be too concerned..... Land Rover...

*so... a sticking relay, swap for another the same?
*the dip switch is faulty.

P.S
*ah haa... so you say there is 12V on the earth pin? with everything off? ..... its must be a short from a 12v source (yeah yeah low beam works right, no rym or reason sometimes)
*unwrap the harness and try to find the short.
*In fact have a look up by the brake booster, there is a harness running along the edge of the wing panel, look for chaffing there, if I am not mistaken (and it does happen all the time) the head lights and other stuff runs along there to inside the firewall.

yes you would think so right, so try disconnecting the dip switch and see if there is still power

Originally Posted by Robmacca

Gents.....

This was the first time I've driven my Puma at Night and all was working OK until I went to turn on HIGH BEAM and everything went dark. I flicked back to Low beam and all OK and then switched again to High Beam and dark again but I did notice that the HIGH Beam indicator on the dash was ON though...

According to what I can find there is a Fuse for the RHS and LHS headlights which seems a bit weird. The Parkers are working fine, Dash lights working fine, High beam indicator on dash all ok, it's just the HIGH beam. I can hear what I can only assume is the Headlight relay click in/out so I'm not sure if I've blown both fuses or it's a dodgy relay.... Its a bit hard in the dark but I was wondering if someone might have an idea as to what has happened? I don't think it could be the light switch in the steering column as all seems OK with Low Beam + the High Beam indicator works as well

wondering if anyone has any ideas ???

Hey Robmacca.....

Have had a quick read of your posts and others.

So most new cars and trucks are negatively switched! This means that power is fed to both filaments in the bulb and then each is passed through to the earth via the headlight switch. My Puma 2013 is negatively switched, I know this as I have just added Led Driving lights to it, and required a negatively switched loom.

So this means that you will read power(Volts) on all wires on the H4 socket. As you are reading the supply, then the voltage potential through each filament.

So this is normal.

It then is a question on the earth during switching! My guess is the switch itself as this is a full flow switch I think.

Have you tried pulling back on the dip switch to flash the high beam? If the high beam works when flashing them(pulling back on the dip switch), then I'd guess the headlight switch is worn/broken?

This is where I'd be looking!

I'm surprised that yours is negatively switched as that's opposite to what the LR factory wiring diagram shows. On mine at the Headlight plug, not all 3 pins have 12v, only 1 which from what I gathered is the negative.... but again I wouldn't be surprised if it turned out that it was negatively switched as this would make more sense having ONE pin always alive and the other 2 for your H/L beams heading back to the switch on the column.....

It just confuses me when I try to interpret the LR wiring diagram as it all seems fairly simple from the diagram but when I try to apply that to the vehicle to fault find it doesn't work.... Wish I was an Auto Electy....

Originally Posted by inken_dave

Hey Robmacca.....

Have had a quick read of your posts and others.

So most new cars and trucks are negatively switched! This means that power is fed to both filaments in the bulb and then each is passed through to the earth via the headlight switch. My Puma 2013 is negatively switched, I know this as I have just added Led Driving lights to it, and required a negatively switched loom.

So this means that you will read power(Volts) on all wires on the H4 socket. As you are reading the supply, then the voltage potential through each filament.

So this is normal.

It then is a question on the earth during switching! My guess is the switch itself as this is a full flow switch I think.

Have you tried pulling back on the dip switch to flash the high beam? If the high beam works when flashing them(pulling back on the dip switch), then I'd guess the headlight switch is worn/broken?

This is where I'd be looking!

Most Japanese vehicles are negative switched, its a common thing, this is correct.

I've got a 2009 Defender sitting in the workshop, its not neg switched.

but the OP plug and wire colours is different to what I looked at.

if thats the case, go back to changing the globes out

Ok .sounds like they are negatively controlled. With both lamps plugged in and lights off if you can probe a test light on the lamp connector.you will have power on all 3 terminals. If so switch on low beam and you should lose power to the middle terminal. This is completing the low beam circuit by providing an earth through the dip switch..if you can decifer the wiring on the dip switch and earth the high beam wire it may narrow down the problem to a dip switch

Well, I've been giving this some thought and having 12v at the bulb plug on all 3 terminals, it just didn't add up to what the wiring diagram shows plus when I turn on the headlights and flick the HB on I'm hearing a relay click. Looking at the wiring diagram it doesn't show a relay except for the HB flash. Also for having 12v at the plug definitely indicates negative switched.

Today, I spent some time tracing wires, etc and I ended up finding a block of 3 relays tucked down beside the inner guard and fresh air intake motor housing mounted on the firewall. Upon closer look there was lots of dirt build up and what looked like green corrosion. Managed to remove the 3 relays and could see the corrosion and what not. I then tested the relays and found one of 3 stuffed. So I'm assuming that is the issue but I probably need to mount these relays in a better spot where water can easily drain away and dry.... To do the job properly, it probably needs bigger wiring too to cater for voltage drop. Hopefully over time I will do this but for now, I'll just try and reposition the relays and put new relays in....

btw: Is there any way of dissolving the green corrosion that is around the spade connections as a temporary measure or is it best to replace them now?

Electrical contact cleaner can from most auto stores