27 replies to this topic

[Ru55boy]

nice looking pannel by the way ru55boy how did you put the lettering on to it?

Cheers mate, I just took it into a key cutters / shoe repair shop in the high street.

[Dan]

Hi Ru55boy,

Sorry I forgot all abut this.

Tell me what sort of switch it is you are using and I'll come up with a circuit for you. From what you've said it sounds like a conventional SPST switch with illumination. Do you want the lamp in the switch to flash in time with the seperate warning lamp? Do you want anything lit as a locator?

[Ru55boy]

Hi Ru55boy,

Sorry I forgot all abut this.

Tell me what sort of switch it is you are using and I'll come up with a circuit for you. From what you've said it sounds like a conventional SPST switch with illumination. Do you want the lamp in the switch to flash in time with the seperate warning lamp? Do you want anything lit as a locator?

Cheers Dan, I haven't worked on the dash since my last post as the head gasket has just taken priority. That's done now.

Yes its a single pole on/off LED illuminated toggle switch, three terminals for power, acc and earth. I've also got a warning light with two terminals a couple of inches away so I'd like that to flash too. Not bothered if the LED flashes or just illuminates.

[Dan]

Does your car use two flasher units or the later single flasher system? Also is the third terminal on the switch for LED power or for LED earth? Does the LED have a built in limiting resistor?

Edited by Dan, 20 February 2009 - 12:06 PM.

[Ru55boy]

Does your car use two flasher units or the later single flasher system? Also is the third terminal on the switch for LED power or for LED earth? Does the LED have a built in limiting resistor?

It was a 1979 1000 auto and it seems to have just the one flasher unit (a small drum shape unit). The 3rd terminal is for the LED earth.
I don't know about a built in resister. Toggle switches

[Dan]

You should have 2 flashers on a '79 car. One round one behind the clocks for the indicators and a square one in the engine bay for the hazards. If that's not the case I'll have to start again.

Does the switch LED only light when the switch is closed? I'm just a little concerned that since it's a permanantly powered circuit the LED will be running constantly and be a battery drain, albeit a small one.

Last questions, promise. It's just tricky to come up with a circuit when I don't know exaclty how one of the components behaves! I've done a drawing though and it's a really simple circuit, no trouble to put together. You'll have to buy specific relays. Answer this last question and if it all seems to work I'll sitck up the drawing.

[Ru55boy]

You should have 2 flashers on a '79 car. One round one behind the clocks for the indicators and a square one in the engine bay for the hazards. If that's not the case I'll have to start again.

Does the switch LED only light when the switch is closed? I'm just a little concerned that since it's a permanantly powered circuit the LED will be running constantly and be a battery drain, albeit a small one.

Last questions, promise. It's just tricky to come up with a circuit when I don't know exaclty how one of the components behaves! I've done a drawing though and it's a really simple circuit, no trouble to put together. You'll have to buy specific relays. Answer this last question and if it all seems to work I'll sitck up the drawing.

I'll check in the morning and find how many flasher units I have. If it makes a difference, I've got the centre binnacle type clocks.

The LED illuminates only when the switch is ON, ie the circuit is complete.

The wires that feed the original hazard rocker switch are a permanent live, an ignition live, two indicator wires and an earth.

[Dan]

Errr, well in that case there is one more question. What colour wires does the original switch have?

[Ru55boy]

What colour wires does the original switch have?

Green/Pink - Permanent live
Green/Brown - Ignition live
Green/brown - return for the above?
Green/White
Green/Red
Black - Earth
Black - return for the above

I assumed the round relay next to the water bottle is my hazard relay. Is the silver reactangular box just to the right of it the second relay you mentioned?

[Dan]

It is indeed. You do have the right type of circuit, you made me a bit worried there! You don't have either a permanant live or an ignition live at the hazard switch, these are the two outputs from the two flasher units. Both the earths are common, an earth doesn't need a return as it is a return. I'm assuming there is also a green/light green connecting the switch to its own warning lamp.

You are going to have to relocate the hazard flasher in the circuit for this to work, that also means you'll have to relocate it physically. Pull it out and check that the wires to it are purple/orange and light green/black as they should be. If so then all is well. Remove the flasher from the cables and join the ends together. Either make a link with some spade connectors so that it is removable or just crimp them directly together. You are going to move the flasher inside the car as part of the new circuit.

You need a changeover relay and a double make and break relay to do this. A double make and break is a special relay with two outputs that aren't connected until the relay is closed, this is different from a twin make and break that has two commoned outputs. It will have a terminal marked 87B, that is very important and without one of these relays you can't make this work easily. You could do the same thing using two standard relays but having lots of relays in a circuit can cause trouble. If you can't find a double contact relay then use two seperate normally open micro relays but make sure they are diode protected. The changeover relay you'll be using as a normally closed relay because single throw normally closed relays are hard to find. The changeover is probably going to be cheaper too.

Common together both the blacks that are connected to the current warning lamp when you make this circuit, and then connect both to the earths of the new circuit. If you leave a gap in the earth loop some of the dash equipment will stop working.

I hope the diagram makes sense, all the wires should join directly into your current wiring and I've included the colours.

Attached Files

•  scan0002.jpg   1.2MB   59 downloads

[Ru55boy]

Thanks for that Dan, it all makes sense but certainly not something I could've worked out myself.

I'll follow your instructions and let you know how I get on.

Cheers

Russ

[Phaeton]

Dan,

Sorry to resurrect an old post but thought better than starting a new one. The wiring diagram you provided I assume was for a toggle switch with a built in LED. If you were to use a standard toggle switch (straight off/on) would the diagram then look like this.

 hazard_withour_LED.jpg   1.15MB   18 downloads

I am also having difficulty in locating the relays, any ideas where to obtain them.

Alan...

[gav]

Old thread resurrection time... is this the correct toggle switch for the hazards? http://www.maplin.co...-pole-type-2343