Switching circuit for Relay trouble

[MudRunnerTD]

G'day guys,

I am doing a heap of wiring in the back of the GU getting ready for the big trip and i am having a little trouble with a relay.

I have installed a 30amp relay in the back to fire up a reverse and camp light and it does not seem to want to fire.??

When i was running the switch circuit wire i considered that the fine wire i was running for the switch side of the relay might be a little small but figured "its only the relay"??? The wire i used is 0.12mm and i have run 4mm wire on the hot side to a 55w reverse light.

I though i might have an earth problem but i have hot wired the light and it works so the problem must be at the relay.

I have piggy backed a wire from the back of the reverse light to the 86 pin too and when i use the switch the reverse lights fire but they are then basically hot wired off the back of the switch so not going through the relay. (It does mean though that the relay is getting power but is it enough? or does it not matter? any is enough?)

I have not checked if the relay is faulty and should swap out another tomorrow but wondering if my trouble is just voltage drop unable to energise the relay??

Your help and wisdom would be appreciated

Cheers MR

[Yendor]

So you have run a 4mm wire from battery + (via a fuse) and connected this to terminal 30 of the relay. Then another 4mm wire from terminal 87 to the light.

You have then used the smaller wire from the switch to terminal 86 and earth terminal 85.

With a voltmeter measure the voltage at terminal 86, it should be around 12 volts. You can also bridge power from terminal 30 to 86 to test the relay operation.

It is a 12 volt relay? it's not a 24 volt relay is it?

[MudRunnerTD]

Hey Rod,

Mate as i posted the thread i saw that you were about so cheers for your help.

Yeah i have actually run something like a 25mm to the rear left side via a 100amp breaker at the battery end and then an isolation switch at the back. The switch goes to an anderson plug on my bar for the camper trailer. I took advantage of the big wire and hooked in there and installed a sub fuse box in the rear left of the drawers.

So the 4mm wire is running from a 25amp fuse in the rear left side across the back of the car to the rear right to pin 30 of a 30 amp relay.

A small wire is also running fused from the left side to power up a strip of LED of the inside of the back door via a switch on the right side. From the hot side of this switch i used the same wire to the second switch for the 55w light going to 86 on the relay.

A small wire is earthed at the Jack compartment to the relay at pin 85

87 is a 4mm wire through the back door and up the pole to the light. The light is earthed off the back door too.

I have bridged 87 to 30 and the light works.

I am concerned about bridging 86 to 30 given the size of the switching wire??? will this be an issue for a 3 second test?

[Yendor]

I am concerned about bridging 86 to 30 given the size of the switching wire??? will this be an issue for a 3 second test?
No issue at all, All we are doing here is suppling direct power to the relay to see if it switches on.

This is the same principle of having Battery + running to a switch and then to terminal 86. We are just bypassing the switch to check relay operation.

See how you go, I have to pop out for about half an hour I will check back then.

Cheers Rodney

[MudRunnerTD]

Your a legend Rod.

Bridged it out and no joy. Relay is junk! New junk! I slipped in a Narva 30 amp and the thing started flicking as soon as I touched the wire.

Working a treat now.

Cheers for your help mate.

[Yendor]

Good stuff,

What brand of relay was it? does it have a picture on the side of the relay of a diode (a triangle with a straight line going across the tip) being connected between pins 85 and 86?