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Hi - A quick question for the electrical engineers and experts out there.  If I fit LED bulbs and associated solid state flasher relay, can I also use the same flasher relay for hazards or do i need a 2nd flasher relay for the hazards?  I am thinking that I can get away with one as the solid state relay is load independent?



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Yes you can 'get away' with one relay Myles.  The hazard switch will need to be a double-pole type as it must connect the LH and RH flasher circuits together with one pair of contacts and connect them to the flasher relay output with the other pair. 


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But the last thing one would wish to do would be to leave the ignition on in such circumstances because it could cook the coil and make it far too easy to nick the car.

My hazard device, which was a Lucas after-market unit (and I seem to recall describing in TR Action how to connect it for each of the TR models) is independent of the ignition.  The article is probably in the Technicalities CD.  Just looked it up - Section J9, from August 1996 TR Action.

Ian Cornish

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10 minutes ago, ianc said:

But the last thing one would wish to do would be to leave the ignition on

Ok then - use a three-pole changeover switch.  The third contact switches the feed to the relay from the ignition-switched circuit to a direct live connection. 



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I use a single flasher unit as you describe but feed it from a permanent live. 
This means that the indicators will work with the ignition off but as I always use a hidden battery isolator when parked it is of little consequence. 

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It depends on the vehicle. The TR7 requires a separate flasher and hazard relay to work. Its nothing to do with the load, but down to the circuit design.

When I first fitted LED bulbs I had an electronic flasher relay & a the traditional thermal hazard relay fitted. To make this work I had to wire 6.8Ohm 50 Watt resistors in parallel with the LED bulbs ...


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This all you need to to do for hazard warning lights using led bulbs, & led compatible flasher relay.  Diagram is for sidescreen TR's, but can be applied to all cars.

The three way switch allows hazards to be on with ignition off.

suitable switches here:



Depending on what size hole you wish to mount it in.


A bit late with my reply as was out of contact all of yesterday !


Edited by Lebro
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Hello, I fitted a Hazard Warning Switch, if I remember from Vehicle Wiring Products, there were 10 or 12wires to it and it was permanently live, when I came to use it, on an unlit road, not very good, so I bought one of these, when I rewire my car this winter I will put a fused 12v socket in the boot, I have connected the light to a magnetic block and it will sit on the boot facing astern, I have tried it out, it will not be missed!, Cheers, Andrew


Cost about £20

Edited by AndrewMAshton
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