Turn Signal Switch with Relays

FireEngineMike

FireEngineMike

Senior Member
I installed a Signal-Stat 900 7-wire turn signal switch per the included directions. I used the 500 flasher included with the Signal-Stat. My truck is 6-volt positive ground. I built a relay panel for the rear turn/brake lights and taillights (and electric fuel pump) because I have multiple light fixtures on each side. My truck is a fire engine and I wanted upper and lower lights. The turn/brake filaments illuminate with either the turn signal switch or brake pedal, but do not flash.
>I ran a jumper from the flasher "L" terminal to the signal input of the left turn/brake relay (bypassing the Signal-Stat). The filament illuminated but did not flash.
>I moved the jumper to the output of the left turn/brake relay (bypassing both the Signal-Stat and the relay) and the filament flashed.

I hope someone can lead me toward a solution.
 
It sounds like the relay triggers don't draw enough current to operate the flasher. Try putting a dummy load, like a light bulb, on the trigger circuit for the relays.
 
40cpe is right the resistance of the relay coils is to high to let the flasher work properly...same happens when using LED bulbs.
Adding resistors used for led´s will fix it if you don´t want some extra bulbs under the dash flashing.
 
I'm trying to wrap my brain around relays. If full voltage to the relay is there. They should operate correctly.


Relays are a switch so they shouldn't have ohms till needed
 
Not sure why you would fit relays to the flasher lights because this will take the load off the flasher unit and prevent it from working. Ditch the relays altogether and allow the flasher unit to take the load of the front and rear flasher bulbs as it is designed to do. My opinion of using rear stop light bulbs as flashers is its dangerous. Always better to have two stoplights working with separate indicator lamps. Some countries require this. Yes I know many of you yanks say its OK and you have never had a problem But over 50 years as an auto electrician tells me otherwise. Now Tinker I think you could use a little more study on electrical theory and then you could give some good advice to others. Not meaning to put you down at all but incorrect ramblings regarding how to fix things is not really helpful to others trying to correct problems. Regards, Kevin.
 
He said he wanted hi/lo blinkers on a truck...as i got it meaning you have multiple turnsignals on each side goin on/off on different times...so you need either a special truck flasher which i highly doubt is available in 6v...or some kind of relay setup.
Putting a couple of bulbs or a resistor parallell to the relay coil would be my first thing to try...
 
As the flasher relay needs two bulbs to flash at the correct rate, I'd be inclined to wire it as normal and then see if the circuit will also pull in a relay and flash at the correct rate. If it does, any number of extra bulbs can be ran off the relay.

A hazard flasher will run 4 bulbs. Is a suitable 6V hazard flasher unit available? If so that might be a way forward.

Mart.
 
flatheadmurre said:
40cpe is right the resistance of the relay coils is to high to let the flasher work properly...same happens when using LED bulbs.
Adding resistors used for led´s will fix it if you don´t want some extra bulbs under the dash flashing.
Click to expand...

This should read is not high enough resistance, correct?

Update: I am not correct here! The resistance in an automotive coil is in the 50-200 ohm range. Much higher that I thought it would be.
 
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JSeery said:
This should read is not high enough resistance, correct? The flasher unit needs to see resistance, such as a bulb filament, to heat it up enough to work. A small relay coil does not provide enough resistance.
Click to expand...

High resistance to me means a higher ohm value...and less load.
The usual led resistors are in the 33-47ohm range if i remember tight...don´t take my word for it...
 
Looked up an automotive relay, and (as almost always :) ) you are correct, the resistance is higher than I thought. The 12v coils run in the 50 - 200 ohm range. The 6v relay coils are lower in resistance.
 
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JSeery said:
That relay (6v) has 22 ohms of resistance in the coil.
Click to expand...

Which is not enough to trigger the flasher...... Would two relays (front and back) provide enough? I have not built the front end relay panel (planned for turn signal relays, siren light relay, headlight relays). The siren light obviously will not work with the relay and flasher.

I jumpered across the relay (signal wire to output wire) and the turn signals and emergency flashers work. Guess I tried to overdo things with the relays. Lights look nice and bright (painted inside of housings white and ran a ground wire to a mounting bolt).

FWIW: I installed a heavy duty solenoid for the siren and used 8-gauge wire for power (so far just mounting bolt chassis ground). The siren spools up like it should instead of the previous "I think I can" rate of increase.
 
So my memory about resistance for leds are 12v...a 21w bulb on 6v draws in the 3a range...so we are talking a big resistor in 2-5ohm range to make it work on 6v.
And power resistors that big aren´t cheap so that electronic flasher looks like a good option.
 
The load resistors are not too bad a price, you can get a 3 ohm for around the $3 - $4 range.
 

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I bought a 4-pack of 50-watt 6-ohm resistors from Amazon for $12.99. I installed two and the flasher works with the relays. Thanks to everyone for your help.
 
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