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Mike's 77 01-20-2009 12:01 PM

Alternating Hazard Flasher
Is there a 2 terminal alternating flasher out there that can be used for the hazards in my 77 f150? I've searched everywhere and all I can seem to find is the 3 terminal flashers. Will these work with a 2 terminal plug? If so, what would I need to do with the third terminal? I read on some website that the third terminal can be used for a secure ground with a wire running off it. Is this true? Any help is appreciated,thanks.

n4aof 01-20-2009 02:49 PM

I'm trying to guess what you are trying to ask.

There is simply no way that a two terminal flasher is "alternating" - unless it is used to control a separate relay.

An "alternating flasher" has three terminals (four if it has a ground). One is the input and the other two are for the alternating outputs -- it alternates power between the two outputs to create the "wig wag" effect commonly seen on emergency vehicle headlights and school bus warning lights.

Regular automotive flashers have two or three terminals -- none of which are normally ground and none of which alternate.

The two terminal flasher has just one input and one output, the flasher just turns power to the output on and off. The output goes to the turn signal switch and/or hazard warning switch.

The common automotive three terminal flasher has one input and two outputs.

The original concept of the three terminal automotive flasher was to remove the indicator circuit from the signal circuit. One output goes to the turn signal switch and/or hazard warning switch to power the signal lights; the second output goes to power the indicator light(s) on the dash. In the typical cheap three terminal flasher, the two outputs are simply wired together internally. In better flashers the two outputs are isolated (at least when the flasher is off)

Any auto parts store should have both two-terminal and three-terminal automotive flashers. It sounds like you can't find a two-terminal flasher in your local store because you are asking for a "2 terminal alternating flasher" and no such device has ever existed.

In the VERY unlikely event that you really can't find an ordinary two-terminal flasher locally and don't want to order one from any of the hundreds of on-line retailers who advertise them, yes you could use a three-terminal flasher. The input terminal is the one marked X, you should break off and/or tape over the extra terminal because it will be hot whenever the lights are flashing on.

Mike's 77 01-20-2009 03:02 PM

Thanks for the info it really helped. What I would like to do is to have wig-wag hazards without spending a ton of money on a complicated setup or a hide away strobe kit. Is there a way to make the 2 terminal plug for my hazards into a 3 terminal plug by do some re-wiring? Or would it be more trouble than what it's worth to try that?

ReAX 01-20-2009 03:11 PM

It will take a second relay and flasher. Basically apply power to both the flasher and pin 30 on a relay. The output from the flasher goes to 86, 85 is grounded. Then 87 and 87a each go to their own light. This way, when the flasher is on, power is going to 87 and when the flasher kicks off, power goes to 87a.

However, your not going to get the same effect as a proper strobe kit. This wig wag, just alternates the two light circuits. Good strobes will have several patterns of flashing the lights and then alternating.

Mike's 77 01-20-2009 03:25 PM

That is probably what I'll end up doing is the hide away strobe kit. Not sure which route to go with the strobes though. There's so many options out there that it's hard determine which ones will work for my application.

ReAX 01-20-2009 03:46 PM

I'd suspect you have sealed beam headlights, and 79 really didn't have a space in the turn signals for them. You could try upgrading the sealed beams for a bulb style lamp. IPCW used to carry a variety of lamps that would bolt in place of sealed beam lights. I think this was the company SealedBeam-Conversion Kits.

Then you could put strobe lamps in these. I would pick a ES manufacture like whelen or Star Signal or Southern VP. Your going to get a very reliable product and all of the fancy patterns.

Mike's 77 01-20-2009 04:26 PM

I'm planning on upgrading the headlights anyways to HID's, but haven't given much thought to putting the strobes in the headlight housing. Will they be as bright when the headlights are on? I'm gonna go with a Whelen hide-away kit with 4 strobes. But what would be the best way to go as far as switches. I don't need anything too fancy or high tech with 10 flash patterns tho.

ReAX 01-20-2009 04:54 PM

Whelen strobes should be pretty decent, I think they are only about 15 watts per bulb. However they give out quite a bit of light for the 15 watts.

Just about any switch will work, rocker or toggle. You probably need 3 spdt switches to handle all of the available patterns, but you could get away with just a power and two position switch to switch between two patterns.

Franklin2 01-20-2009 11:58 PM

We just put in a Whelen kit on a dump truck. You only need a simple on-off switch to make it work. If you want to get fancier, you can add other switches to toggle through the different patterns, but they are still just simple momentary switches. You just keep bumping the switch and the box will scroll through the different patterns.

Mike's 77 01-21-2009 01:05 PM

What watt power unit would be recommended for these? I've seen them from I think 35W-90W and am unsure of the differences.

ReAX 01-21-2009 01:53 PM

It appeared to me back when I was dealing with Star Signal, that 15watts per bulb was normal. The 6 channel/bulb power supplies were in the 90w range, the 4 channel/bulb P/S were about 60w and the two channels were in the 30w area.

I think there were a few choices of 75w or so on the four channel, but I never tried one.

The PS that uses the momentary switch, was that one of the newer smart PS? All of the install sheets I've looked at need the wires connected to select the pattern, much the way the light bars work on the switch panels.

Franklin2 01-21-2009 06:34 PM

I went to the Whelen site and I think the one we used doesn't have a online manual. The others I looked at used maintained switches in combinations to make the different patterns.

Here's a link that looks like the one we used.

Whelen Engineering - Systems, Hide-A-Way Strobe

Yardgnome 01-24-2019 11:55 AM

Question along the same lines as Mike 77 but with a little twist. I have a small flasher unit from STL and would like to be able to tap into tail, marker and roof clearance lights, is there a way to do so?

Franklin2 01-24-2019 04:25 PM

Originally Posted by Yardgnome (Post 18438319)
Question along the same lines as Mike 77 but with a little twist. I have a small flasher unit from STL and would like to be able to tap into tail, marker and roof clearance lights, is there a way to do so?

What year truck? If it's a newer one it might be iffy. You want to flip a switch and make all your marker lights flash? And then flip the switch off and they revert back to normal?

Yardgnome 01-25-2019 05:16 AM

Thanks for the reply. It's a '15 F350 and yes that's what I had planned. The flasher unit would be tapped into the "main" wire to all exterior lights. I know it might not be possible, but I thought there might just be a chance.

Thanks again.

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