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I bought a hazard warning light unit from an eBay supplier a couple of years ago but have just gotten around to fitting it. It has a flasher unit, switch and what I take to be two diodes in the small wiring loom. But the system is not working correctly. It's been suggested that one of the diodes may not be working so rather than sending the whole thing out I'm thinking of just replacing it / them as they have simple male / female terminals. Does anyone have any knowledge of such things and might help in identifying what they are so I can try and source a replacement?

 

 

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Paul

Edited by PaulAnderson
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Is such a specialised test for a malfunctioning diode necessary that it must be posted to the specialist?

 

A multimeter in resistance mode will show so many Ohms one way, and an open circuit if the leads are reversed.

 

John

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Paul.

How was the diode assumed to be duff ?

As John says, it is easy to test it, if you don't have a multimeter, then just make a simple circuit:

 

Wire from battery +ve to bottom end of diode (in your pic), (current passes in the direction of the arrow), from top end of diode wire to a 12V bulb, wire from other side of bulb (the metal cap) back to the battery -ve. lamp should light.

Reverse the diode connections and the lamp should not light.

 

From your photo the diodes may need to go the other way round.

 

Bob.

Edited by Lebro
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I've got a couple kicking around somewhere with the idea of fitting an led in the place of the standard filament for the turn signal indicator....never got round to it though, but I have got a beeper that comes on after about 20 flashes.

 

Then I thought why not move the flasher unit up behind the dash where it should be......never got round to that either....too busy ragging the car around the streets!

Edited by DaveN
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In case my reply above made anyone think I knew what I was talking about, why on earth does a hazard warning system need diodes?

And TEN AMP diodes too?

TWO of them!

 

John

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Have just popped back into the garage and tested them and I do get open circuit one way and a resistance the other. Not sure what range the meter should have been set to but it suggests that they may have just been incorrectly fitted, else it's something else. I'll check the rest next time I'm in the garage.

Thanks

 

Paul

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Its to allow the flasher unit to power up all of the car's indicators without upsetting the ordinary flasher system John. Basically the diodes are used to connect both sides together to the common hazard flasher unit, but because the diodes are back-to-back, current cannot pass between them when the ordinary flasher system is used. You do need two diodes but they are so cheap it makes little difference to the price so you might as well use 10A ones to have a margin of safety.

Edited by RobH
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The wiring should be pretty simple Paul - see attached. The new hazard circuit is shown orange. The diodes are shown as for negative earth, if the car is positive earth they need to be the other way round. Depending on the hazard flasher unit supplied, it might also have an earth connection which I have not shown.

post-7865-0-03642700-1493708405_thumb.jpg

Edited by RobH
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Agree with Rob above. plus:

 

Looks to me that

1) the kit is meant for a -ve earth car

2) the flasher unit is electronic

 

either way if your car is +ve earth the diodes will need reversing, & possibly the flasher unit, or the flasher unit may not work at all.

 

Bob

 

P.S.

I have a home made Hazard warning system on my'3, just used a multiway toggle switch, which joined the two sides together, & to the flasher relay, & injected permanent +12V to the existing flasher relay with a diode to prevent the ign circuit becoming live.

Edited by Lebro
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I haven't a clue when it comes to electronics (and many other things). Would it be somehow simpler to have both front then both rear indicators flashing alternately. From most angles they would look like regular hazards. Or is that illegal? No doubt you more knowledgeable will correct me.

Rod

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No Rod - I'm afraid that would be a rather difficult to do. You would need to separate the front/rear indicator circuits in the car wiring loom and then connect them to a hazard flasher unit with change-over contacts (if such a thing is available) or use a relay. Then you would have to find a way of disabling it so that the indicators work normally the rest of the time, which would probably need four or more diodes or perhaps more relays or a muti-way switch. It could be done but a lot of work and added complication for no gain. Sorry.

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Thank you, RobH, for the explanation and even more the diagram!

All is now clear.

 

Learn something, every day (Socrates?)

John

Edited by john.r.davies
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You could use two relays as follows

 

Relay 1 (Right hand indicators)

Terminal 30 - from the Hazard flasher output

Terminal 87 - To Right hand indicator bulbs

Terminal 86 - from the Hazard switch

Terminal 85 - to ground

 

Relay 2 (Left hand indicators)

Terminal 30 - from the Hazard flasher output

Terminal 87 - To Left hand indicator bulbs

Terminal 86 - from the Hazard switch

Terminal 85 - to ground

 

But two 10 Amp Diodes are a lot simpler and a lot cheaper.

 

TT

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Thanks for the wiring diagram RobH. I had a look at the non-functioning hazard warning light installation late this afternoon and am a little confused as to what’s going on.

The original instructions for the kit said that there's four wire connections;

  • Switch side positive (red wire) & negative (black wire)
  • Flasher relay side ; two wires (black & red) one to each of left and right indicators and it does not matter which way round they go.

The hazard switch that came with the kit has three connections on it and it has an illuminated LED when it’s turned on.

There’s one wire going into the flasher unit (terminal marked X) from the switch and two going away from it (terminal marked L) to the two sides of the car.

The problem is that when it’s wired in and operated only the right hand indicators are flashing. When it’s not switched on and normal indicators are used from the column switch both side indicators come on no matter which side you switched. The diodes appear to be installed as per your schematic diagram with the arrows giving the direction of flow away from the flasher. These symptoms are why the person who installed it suggested it may be a diode issue but they appear to be working according to my multi meter.

 

The flasher unit is marked 12V, 21WX4, Max 94W, 1H0813

 

Any suggestions please?

 

Paul

 

34476322286_74ed19998b_z.jpg

Edited by PaulAnderson
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If one of the diodes is connected the wrong way round, it almost fits your symptoms, but not quite. The hazard flasher would only operate one side as per your fault and the indicators would all flash together - but only when the indicator switch was in one direction, not both.

 

What car is this - TR4?

 

Are you sure the leads/diodes are connected correctly to the flasher wiring- one to greeen/red, one to green/white?

 

When you did your meter test of the diodes, did they both conduct in the same direction as shown by the arrow ? (if not then one of them is the wrong way round internally)

 

If you swap the two diodes over, does the hazard flasher then work only the LH lights? Do the indicators still flash all together?

Edited by RobH
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