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Hazard Switch & Indicators - fault diagnosis


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#1 LandyManLuke

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Posted 12 April 2008 - 09:53 PM

I wrote this for another forum, I thought it might be useful here too.


The hazard switch and indicators often cause problems in defenders, most commonly the indicators stop working, but the fault is actually with the hazard light switch.

This post aims to explain how the hazard switch works, why it's malfunction stops the indicators working, and how to test for and diagnose the fault.

To get to the back of the hazard switch, remove the two screws and pull the switch panel out. you'll then see this.

Posted Image

The multi plug has 7 wires going into it, there's also the Black (red trace) and Black wires, which are connected directly to the switch body. these are for the indicator in the switch itself.

Black(red) - indicator supply
Black - earth

Remove the multiplug, you will then see the two sets of pins, x3 and x4, top and bottom (as viewed in the photo, not as mounted in the dash).

The top set are concerned with powering the flasher unit, the bottom set dictate what the flasher unit actually lights.

Posted Image

This picture shows the 4 wires that connect to the bottom set of pins

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And this picture shows the 3 wires that connect to the top

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To make things easier to see, here is a schematic of the switch.

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With the Hazard switch in the 'off' position

'Suppy to flasher' is connected to 'Light switch supply' - which comes on with the second click of the ignition switch

With the Hazard switch in the 'on' position

'Suppy to flasher' is connected to 'Permanent Supply' - 12vDC

*Flash* is connected to 'Left Indicators', 'Right Indicators', and the 'Switch tell-tale'

What this means is, if the switch is faulty, the flasher unit doesn't get a power supply, so it can't flash the indicators via the indicator switch on the column.

You can test the switch using a multimeter (continuity or resistance), or test lamp. You can also test the vehicle wiring as follows.

You will need a fused piece of wire (or test lamp), you don't want to risk a dead short if you get it wrong.

This is what i made to test the wiring, the lowest value fuse i had was 5A.

Posted Image

If you link 'permanent supply' (purple) to 'Left indicators' or 'Right indicators' the indicators on that side should light, constantly though, not flashing. this proves the bulb wiring is ok and you have supply to the loom plug.

If you link 'permanent supply' (purple) to 'supply to flasher' (light geen), the indicator stalk switch should work the indicators as normal (flashing). The indicator switch is connecting *flash* to 'Left Indicator' or 'Right Indicator' - the wiring is duplicated at the stalk switch. If you want to make a seperate link wire you can replicate the stalk switch action at the loom plug as well.

You can repeat the two tests above, using 'Light switch supply' instead of 'permanent supply', the ignition switch will need to be on the second click.

'Switch tell-tale' is the live supply to the bulb in the switch housing, it is grounded by the seperate black wire connected to the switch body.
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#2 western

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Posted 12 April 2008 - 09:56 PM

Another Great effort Luke :D

I'll have a link put in the Tech Archive.
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#3 tweetyduck

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Posted 20 January 2010 - 04:05 PM

thanks a mil this helped me no end today. In the end it was the fuse for the hazzards that made them not work. But i learnt how they work in the process.
THANKS.

M reg 1994 110 300Tdi CSW (MA9xxxxx)
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#4 Mo Murphy

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Posted 21 January 2010 - 12:16 AM

Good write up Luke, nice and clear.

Mo
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#5 Tree Surgeon 130

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Posted 28 February 2010 - 06:57 PM

For info, the wire shown as dark green here is white with a green trace in the TD5 defenders. Make sure this is not confused with the green with white trace wire.

Kev

#6 Maverik

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Posted 08 July 2010 - 11:58 AM

For info, the wire shown as dark green here is white with a green trace in the TD5 defenders. Make sure this is not confused with the green with white trace wire.

Kev


Also for info, for a TD5 HZ switch, to get the little light in the button to illuminate you join the black/red wire with the orange/red wire.
My 86reg 90 with original loom, the dark green wire had a small white rubber band marker on, this attaches to the White with green trace wire as Kev says.

C Reg 1986 LR90 with Disco 200Tdi Conversion Build thread here.

P Reg 1997 Disco 1 (Camel)

M Reg 1995 Disco 1

P Reg 1996 Disco 1 (spares)

F Reg 1989 110

H Reg 1991 110 (Fergal the Camel)

F Reg 1989 110 Hi Cap (TBN)


#7 jimmy mad

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Posted 04 November 2010 - 07:38 AM

Hi could some please help have mot tommrow at 2 pm have all indicators but no hazards tryed 3 switches in my mates truck they all work but put any in my 90 all indicators work but no hazard lights and one is brand new ???

#8 jimmy mad

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Posted 04 November 2010 - 08:13 AM

could it be all switchs cause its only the switch that dose the hazards not any other wiring as i understand from this post ?? :blink:

#9 LandyManLuke

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Posted 04 November 2010 - 10:57 AM

If you've tried 3 switches that all work fine in anothe vehicle, I think it is pretty safe to say it's not the switch.

Do you have a multimeter or a test lamp?

If you have a spare length of wire or lamp you can test the wiring at the hazard switch connector, as described above.

Have you done this?
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#10 jimmy mad

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Posted 04 November 2010 - 01:53 PM

i have tried it as described, all works both lights come on and switch for indicators is correct as they function, but can't get the hazards to work, but can't get the relay to work, have tried two new relays but still no hazards, but all the switches and relays the indicators function fine just cant get hazards to work starting to panic cause mot comming fast :(

#11 LandyManLuke

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Posted 04 November 2010 - 02:21 PM

Ok, slow down a bit.

If you link 'permanent supply' (purple) to 'supply to flasher' (light geen), does the indicator stalk switch work the indicators as normal (flashing)?

Do the test with the ignition off.
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#12 Terra Dog

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Posted 13 November 2010 - 08:13 PM

How do you test the switch?

#13 western

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Posted 13 November 2010 - 08:40 PM

it either works or it doesn't, it's just a rocker switch, maybe the slider bit inside is dirty or worn.
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#14 Terra Dog

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Posted 13 November 2010 - 08:56 PM

I've just been down to the landy and tested the switch with a multi meter. At first it was'nt working when tested, then when I switched it on and off it started working. It must have been a bit dirty inside. One of the pins/terminals on the back of the switch was a bit corroded so I cleaned it up. Put it back together and the hazards started working again. Happy Days.

Thanks.

P.S a very helpful thread.

#15 C18RCH

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Posted 02 December 2010 - 04:46 PM

The flasher relay on my 1988 110 is energising (clicking) all the time even when the hazards/indicators are not turned on. The strange thing is that the indicators are not coming on when it clicks. The indicators work fine when selected but when turned off again the relay continues to click.

The clicking is not consistent as when the indicators are selected but instead erratic. If I turn my lights on it reduces the frequency of the clicking but it still does it occasionally.

I put the M.meter across the light green and earth on the flasher relay and it always has 13v across it (with engine running) as it ony happens with the IGN on. If I turn the lights on it drops to 12.8v and it reduces the frequency of the clicking.

I assumed this was due to a short cicuit so I pulled my landies wiring loom to pieces and sepreated all the wires but it still happens. I have checked all the indicator associated connections and cannot find a short there, so I am at a loss as to what else it could be.

The only theory I have left is because it only happens with the IGN on there is a fault with the hazard switch across the Green - Light green connections but I have checked this with the m.meter too and it appears to be fine too.

I have read the following article and all works fine.

http://forums.lr4x4....=1

BUT I CAN'T STOP THE CLICKING ITS DRIVING ME MAD!! :wacko: :wacko: :lol:

Does anyone else have any thoughts?

#16 C18RCH

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Posted 11 December 2010 - 09:45 AM

Ok so I've changed the Hazard switch for a new one which has reduced the frequency ofthe clicking but not erradicated it entirely which leads me to believe that the switch was on its way out but not the cause.

Since it only happens with the ingnition turned on then it leads me to believe the fault is IGN feed but I cannot find any shorts on this line and all voltages/currents are correct.

The only thing I can think maybe the problem is the trailer socket so Im going to disconnect that now and see if it cures it. Beyond that I am lost.

:unsure:

#17 western

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Posted 11 December 2010 - 11:34 AM

have you tried a new or known good flasher relay ?

it maybe your relay has a problem.
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#18 C18RCH

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Posted 12 December 2010 - 08:52 PM

Yeah, have changed relay, hazard switch, steering column switches. Disconnected trailer electrics but has made no difference.

Have drawn a circuit diagram which I'll upload later when on computer rather than iPhone. It may help someone else out in future.

#19 LandyManLuke

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Posted 12 December 2010 - 09:39 PM

Since it only happens with the ingnition turned on then it leads me to believe the fault is IGN feed


I doubt it. I suspect the ignition needs to be on to make the problem appear, but is not actually the cause of it.
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#20 C18RCH

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Posted 13 December 2010 - 12:48 PM

Diagram as promised

Sorry, I don't think the IGN feed is the promblem but rather the problem is somewhere on the IGN feed.

As you can see from the diagram the flasher relay uses the same power feed to activate the relay and also power the bulbs which would imply that the flasher relay should click constantly as it always has power.

I know it is not as simple as this, I assume the other components in the flasher relay and Haz switch are there to prevent this. My understanding of electrics doesn't go as far as understanding how this actually works. Can anyone explain this?

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