Disco 1 Headlight relay?

Head lights have stopped working? Dipped beam works fine. Put full beam on and dipped goes off as it should but full beam does not come on so I am left with just side lights. Tried swapping relays but no joy. Fuses are good and it's both lights not just one. Relay or steering column switch? How to test?

Looking at the wiring diagram, I'd say that the only relays in the headlight circuit are for the Dim/Dip.
The main beams are switched directly by the steering column stalk.
Does the headlight flash work?
I presume that you've checked the stupid stuff first, like blown main beam filaments.

brian47 said:

Looking at the wiring diagram, I'd say that the only relays in the headlight circuit are for the Dim/Dip.
The main beams are switched directly by the steering column stalk.
Does the headlight flash work?
I presume that you've checked the stupid stuff first, like blown main beam filaments.

Click to expand...

After reading your post I realised I had not checked the bulbs. I had checked the fuses and swapped loads of relays you all have permission to call me a #*&+ !! Both full beam at the same time, go figure?
Thanks mate, all fixed now

currymunster said:

After reading your post I realised I had not checked the bulbs. I had checked the fuses and swapped loads of relays you all have permission to call me a #*&+ !! Both full beam at the same time, go figure?
Thanks mate, all fixed now

Click to expand...

There's a secret circuit buried deep inside a Landy, nobody knows where it is, but it's sole purpose is to cause faults that confuse and confound. It's programmed to do things like blow both filaments at the same time just to get you tearing your hair out.

brian47 said:

There's a secret circuit buried deep inside a Landy, nobody knows where it is, but it's sole purpose is to cause faults that confuse and confound. It's programmed to do things like blow both filaments at the same time just to get you tearing your hair out.

Click to expand...

I agree so much - just to wind the owners up!! At least with the older cars we hold all the cards. Me thinks with the newer ones the main stealer holds all the cards, as well as our bank ones!!

Electrickery............ that is all....

Back when I first got the Disco, third week or so, I hooked it up to my caravan and went through the lights fixing bulbs, grounds, cleaning corrosion, and spreading dielectric grease. Stuffed my breaker bar between the seat and brake and adjusted it up to light the brake lights up. Change a few bulbs and all the sudden the lights go out.
Ok. no biggie, I am working on the trailer lights so obviously it is some fault in the plug, or wiring. Tear it all out.
Everrything is actually sweet. Clean, well insulated, properly tied off. all bulbs good. Ok. I am an idiot. But the damn brake lights are dead, car and caravan. Come inside and search LZ. Read about the cheapest brakelight switch
to have ever been placed on a car, I had checked the switch and it appeared to be working, but it works by breaking
the circuit, not completing it. take it out for the third time, tear it apart, bend the contacts a bit and make them work properly, squeeze the little bit of crap back together, shove it back in and voila! brakelights. 5 hours later and the wife
seriously doubting my decision to buy the Disco. To be fair, the next 5k miles were trouble free with the exception of
a rear shock falling off. No threadjacking intended. just thought it might give you a laff.

brian47 said:

There's a secret circuit buried deep inside a Landy, nobody knows where it is, but it's sole purpose is to cause faults that confuse and confound. It's programmed to do things like blow both filaments at the same time just to get you tearing your hair out.

Click to expand...

That's why it's called 'electrickery' ...

BTW. losing both brights at the same time suggests a hard short somewhere, probably intermittent.
I know my head light connectors are both quite melted and require a great deal of attention and careful handling

ironie said:

BTW. losing both brights at the same time suggests a hard short somewhere, probably intermittent.
I know my head light connectors are both quite melted and require a great deal of attention and careful handling

Click to expand...

change them for ceramic ones.

The Mad Hat Man said:

change them for ceramic ones.

Click to expand...

A fine idea. Ta

ironie said:

BTW. losing both brights at the same time suggests a hard short somewhere, probably intermittent.
I know my head light connectors are both quite melted and require a great deal of attention and careful handling

Click to expand...

I'm sorry, but I fail to see how a short circuit would ever drive the available voltage on a vehicle electrical system to more than 12 volts (nominally and say 15 volts absolute max.) If you take a 12 volt headlight bulb and connect it directly across the battery it won't blow, and the bulb will only draw as much current as it needs to glow fully. That nice Mr.Ohm said that the only way to cause the current to rise through a resistive load is to increase the voltage across it and on a vehicle it doesn't go above 12 volts (15 V).

If you're having trouble with your headlights then consider @The Mad Hat Man's modification to install relays as well as the ceramic bulb holders:-

https://www.landyzone.co.uk/land-rover/headlight-wiring-upgrade.72348/

Mr ohm said if you decrease resistance, you increase amperage, not current. Currymuster said both high beams were blown. This is why fuses have different amperage ratings, some times fuses fail to protect the circuit. and headlight filaments are just fuses as well, the next weakest link. The relay idea is a fine idea. It does indeed make a safer circuit.

Ampere is a measure of current.

current is the pipe, it remains constant in a system as long as the supply is constant, resistance is the valve, amperage is the working load decided by the level of resistance.

Ohm's law states that the current through a conductor between two points is directly proportional to the voltage across the two points. Introducing the constant of proportionality, the resistance, one arrives at the usual mathematical equation that describes this relationship

where I is the current through the conductor in units of amperes, V is the voltage measured acrossthe conductor in units of volts, and R is the resistance of the conductor in units of ohms.
(added useful facts)
My analogy is poor, but effective, I continued on in the same vein as you, using current synonymously with voltage.

Electromotive force is measured in Volts, Resistance (and impedance) is measured in Ohms and current is measured in Amps. In this case the voltage is the output of the battery and will not change even if there is a short circuit.

the output of the battery is expressed in CCA (cold cranking amps) probably 700-800 delivered @13.7 volts or so
fully topped off. Hence why you can start your vehicle. your headlight circuit is fused @10 amps your headlight (typical h4 @55watts) draws about 3.7 amps. a hard short can draw as much amperage as the fuse and wiring
permit before the magic smoke escapes or a fuse wire or filament burn through.

http://www.onlineconversion.com/ohms_law.htm - here is a cute toy to play with

My apologies Currymuster for defecating all over your thread. I should grow up. I am working on it.

@ironie
This is an example of why electricity can be so confusing to some people.

Voltage measured in volts is either the measure of electromotive force (EMF) or potential difference (PD) the main difference between the two is EMF is the off-load voltage and PD is the on-load voltage. Shown as "V" in your drawing.

Resistance or impedance is the value of the load, the opposition to the flow of current, measured in Ohms. "R" in the drawing. In an alternating current circuit the load value is impedance but still measured in ohms, but in low frequency circuits the principles are essentially the same.

Current is the flow of electricity, measured in amperes or Amps. It's what some people call amperage and is shown as "I" in your drawing.

It is a misconception that a battery or other type of supply can supply any more than the terminal voltage which I say is in the case of a vehicle a nominal value of 12 volts, but that can increase up to roughly about 15 volts when being charged by an alternator.

The current (or amperage as you call it) being drawn from the battery is dependant on the value of the resistance of the load and the voltage of the supply, both of which remain largely constant and not what the battery is listed as able to supply such as its CCA, or the value of the fuse. If the load is a high resistance value, a lower current will be drawn and if the load resistance is a low value then a higher current will flow.

Ohm's law in the form of a formula states that:-


where "I" is the current in amperes, "E" is the electromotive force in volts and "R" is the resistance of the circuit.

I can see where your assumption is going wrong. First you are trying to introduce a term called "amperage" into the system when there is no call for it. Secondly your assumption is that the current remains the same, and tied to figures stated for things like the CCA.

As I've already said, a 55w headlight bulb even when it's connected directly across a 12 volt battery with a CCA of 1000 amps and no fuse in the circuit will still only draw 3.7 amps. It will draw the same current from a battery with a CCA of 800 amperes or 600 amperes or even a power supply with a maximum output of 30 amperes.

Don't ask me how I know, I've only been a radio, radar and electronics engineer for more than 40 years and Ohms law hasn't been changed since I had it hammered into me way back in the mid 1960's.

I just cant believe that there is an argument about Ohms law! - I thought this was agreed by 1850?