Fault Found:No side/head/tail lights - I've replaced switch

MrWorf · Jan 5, 2019

I've had intermittent problems getting any lights to come on, so I replaced the switch. All seemed ok until this afternoon. Now nothing. Is there a relay on a Defender TD5 (1999), or may be I need to look at the stalk ?
Thanks in advance for any suggestions you might have.

doriz · Jan 5, 2019

Check you main beam stack by bypassing the switch - as ridiculous as this sounds the connectors fail especially if you have some spots rigged directly to the stalk.

MrWorf · Jan 6, 2019

Hi Doriz, and thanks. I think I've read else where the stalk might be an issue. But just for clarification. A faulty stalk would stop all side / tail and head lights from coming on ? If so, I'll just go ahead and replace it I think.

mojo247 · Jan 6, 2019

Have a look at the big fuses under the bonnet. I think they are the same for the td5.

mojo247 · Jan 7, 2019

or is it under the seat?

mojo247 · Jan 7, 2019

https://www.lrworkshop.com/electrics/defender-2002my/fuse-boxes-earths-and-headers

MrWorf · Jan 9, 2019

mojo247 said:
https://www.lrworkshop.com/electrics/defender-2002my/fuse-boxes-earths-and-headers

Really useful Mojo247 Thank you.
When I've got the starting problem fixed (another thread), I'll investigate further.
Thanks for going to the trouble of attaching this info - Great.

MrWorf · Jan 9, 2019

MrWorf said:
Hi Doriz, and thanks. I think I've read else where the stalk might be an issue. But just for clarification. A faulty stalk would stop all side / tail and head lights from coming on ? If so, I'll just go ahead and replace it I think.

Doriz, my new stalk arrived by post. This weekend's gonna be busy - Thanks again.

doriz · Jan 9, 2019

Just remember to put aside a good couple of days. No doubt the screws will be rusty and the fu fu valve will need recalibrating...defenders

MrWorf · Jan 9, 2019

Ha ! Ok on that score. The fufu valve has been tuned lately, and I've got some tablets if it starts to let go

MrWorf · Jan 19, 2019

New main beam / indicator stalk installed today - but still no lights (side / dipped / tail).
Main beam flash works ok.
My question is if I describe the following tests carried out at the switch - does this look like I have Short ?
Live feed to switch (brown) constant live (but strangely registering 10.5 volts).
Switch the switch to side lights position, and brown live wire drops to 0 volts.
The Red side light wire also shows 0 volts when the switch is on.
A continuity test between red wire (side lights) and earth shows 0 resistance with switch off
A continuity test between blue wire (dipped) and earth shows full resistance (no continuity)
Switch the switch on to side lights and a continuity test between brown permanent live and earth shows 0 resistance.
Switch the switch to dipped and the same test on blue wire shows no resistance.
A lot to digest - sorry, but I'm thinking it might mean I have a short on the side light circuit ??
Open to suggestions, but also if I'm right, is there a place to look first - is it a common fault ?
Thank you in advance (again)

mick 1986 · Jan 19, 2019

MrWorf said:
New main beam / indicator stalk installed today - but still no lights (side / dipped / tail).
Main beam flash works ok.
My question is if I describe the following tests carried out at the switch - does this look like I have Short ?
Live feed to switch (brown) constant live (but strangely registering 10.5 volts).
Switch the switch to side lights position, and brown live wire drops to 0 volts.
The Red side light wire also shows 0 volts when the switch is on.
A continuity test between red wire (side lights) and earth shows 0 resistance with switch off
A continuity test between blue wire (dipped) and earth shows full resistance (no continuity)
Switch the switch on to side lights and a continuity test between brown permanent live and earth shows 0 resistance.
Switch the switch to dipped and the same test on blue wire shows no resistance.
A lot to digest - sorry, but I'm thinking it might mean I have a short on the side light circuit ??
Open to suggestions, but also if I'm right, is there a place to look first - is it a common fault ?
Thank you in advance (again)

The 10.5V isn’t really that strange. When you use your test leads on your meter, your basically finding the voltage “difference” between the two probes. So if you used an earth wire/point, and it’s not that great an earth, 10.5V would be “normal”. Where did you have the black probe when testing?

Next observation, you can’t test resistance with power turned on. It doesn’t work. You need to remove at least one battery terminal to do a proper resistance test.

MrWorf · Jan 19, 2019

Thanks Mick 1986.
The black probe was wedged behind the bonnet release bracket in the footwell.

mick 1986 · Jan 19, 2019

MrWorf said:
Thanks Mick 1986.
The black probe was wedged behind the bonnet release bracket in the footwell.

That’s not a particularly good earth point. You would be better off adding a length of wire to the black probe, and going direct to the battery terminal.

Personally when I do resistance based fault finding, I will remove the positive battery terminal, and put a crocodile clip on the earth terminal. It’s the easiest way of ensuring you are on the best possible earth. When doing test, try and quote numbers too, as what one person sees as an “open circuit”, might not be, same can be said for a “short circuit”.

MrWorf · Jan 19, 2019

Thanks Mick 1986 Sound advice.
I'll resume investigation tomorrow. Great to know such a wealth of experience is on hand here !

mojo247 · Jan 20, 2019

Did you say you changed the main switch?

MrWorf · Jan 20, 2019

Hi Mojo247, Yes I've replaced the main switch and the indicator stalk with brand new after market parts.
I have a dim dip relay on order now after reading other owners accounts of the same problem.
I was out in it today and mysteriously while repeatedly trying the lights, they eventually came on !
May be something to do with temperature in the cab ??? I had the blowers on.
Also when I got home, I was trying various switch combinations to see if it all worked, and when I tried main beam, there was a funny buzzing momentarily from behind the clocks.
More evidence I hope - it's the dim dip relay ? I'll guarantee they wont work again tomorrow

I'd welcome all suggestions. As proven with my starting problem thread, this forum has proven really valuable !
Thank you.

MrWorf · Jan 20, 2019

Oooh, I forgot to say, while testing it home - while they were temporarily working again, I had no dim dipped lights on side light setting. only the little side lights came on.

mojo247 · Jan 21, 2019

sounds like the dim/dip!

MrWorf · Jan 26, 2019

I've now replaced the dim/dip relay and there is no change. No lights at all.
The key to this must lie in the fact that with the light switch off I read about 10 volts at the live feed to the switch.
When the switch is on it reads zero volts.
By my reckoning you only get 0 volts if both probes are on the earth side of the circuit so does this mean a short somewhere ?

Fault Found:No side/head/tail lights - I've replaced switch

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