wiring lights under truck -- questions on relay

[Apexdisco]

I'm wiring up two lights to the undercarriage and just figured out that I need a relay for them to function correctly. They're located in the front. Two more will go in the rear next week.

Initially I wired up the light using an inline fuse. The switch I'm using has three connectors - earth, load, power.

I'm going to pick this relay up tomorrow. http://www.radioshack.com/product.a..._name=CTLG_011_002_013_000&product_id=275-226
How many connectors does this relay have? And where exactly do I need to run the wires to and from?

The two lights are wired together and connected over to the inline fuse, which is connected to the battery.

I already have the light switch mounted and a good ground.

 

[Steve Rupp]

This should help:

http://www.discoweb.org/lights/2.jpg

http://www.discoweb.org/lights/4hellas.htm

 

[Apexdisco]

Thanks. That does clear things up.

 

[Apexdisco]

What am I doing wrong?

I've got a relay now. And all the wires are connected to it correctly according to the diagram.

The lights are hooked into the relay.

The power line from the battery via a inline fuse is connected to the relay.

The ground is connected to the relay and attached to the truck.

The wire to the on/off switch is connected.

On the switch itself, there are three connectors. I've moved the power (from the relay) to either load or power. The ground is hooked up. Lights don't turn on.

Will this work with only the one connector attached to either?

I'm confused.

 

[Steve Rupp]

The relay is inline with the wire you were using to go from the switch to the lights (basically, cut the wire going up to the lights, add the relay plus the new hot and ground). Instead of the switch turning the lights on, it's now turning the relay on. You can use the same power supply for the relay and the switch. The ground doesn't need to be hooked up on the switch unless you want the light to work. That's all the ground is for on the switch. The relay then turns the lights on using power from the battery not the switch. This eliminates the possibility of melting the switch from exceeding it's current rating.

 

[Apexdisco]

The relay is inline with the wire you were using to go from the switch to the lights (basically, cut the wire going up to the lights, add the relay plus the new hot and ground). Instead of the switch turning the lights on, it's now turning the relay on. You can use the same power supply for the relay and the switch. The ground doesn't need to be hooked up on the switch unless you want the light to work. That's all the ground is for on the switch. The relay then turns the lights on using power from the battery not the switch. This eliminates the possibility of melting the switch from exceeding it's current rating.

I think that's what I got. I'll check it again. I'm also going to down a couple Yuenglings. Maybe that will help keep the swelling down in my brain.

 

[Apexdisco]

Still no worky. Must be a bad relay.

I don't know.

Ok, one last shot. Here's a picture of what I've got.

#1 = to on/off switch
#2 = the lights
#3 = battery power

unmarked = ground

Good?

 

[Steve Rupp]

You're relay is hooked up wrong. Switch terminal 2 with your ground. This should work. However if you cut the wire at the relay it looks like it should be the two small wires as your "to light" and "to switch". The wire going to the battery should be the larger wire. Now I can't really tell from looking but I do know that if the wires are marked correct to your diagram, switch terminal 2 with ground and it should work.

 

[Apexdisco]

I just flipped them and still not working.

Something has got to be wrong with the relay. I've tried every wire combination. And disregard the different wire gauges, thats just my shitty wiring job.

We'll try it again tomorrow night.

Thanks for your help, I really appreciate it.

 

[Apexdisco]

to anyone not watching the election; here goes again.

I bought a new relay and hooked up the wires - still no worky. I'm dumbfounded.

After examining my hella relay I noticed two green wires going over to the on/off switch.

One for load(lights) and one for power. Now I'm trying to wire my "other" lights with only one power light going to the on/off switch. (see above if you're confused).

Do I need two wires going to the on/off switch? Holy crap, I feel stupid.

 

[traveltoad]

Start by making sure your switch is wired correctly. If you conect it with a grounded light... does the light turn on? Then make sure you are connecting your now correctly wired power lead (from the switch) to the relay. When you power the switch the relay should click. You must use the correct two posts to get it to click. The remaining two posts are the power feed to the light.

 

[Apexdisco]

traveltoad - on/off switch has three posts. I have the ground hooked up and one power wire. I've had it attached to power or load, but not both at the same time.

I've heard that click by switching the wires around. It doesn't match up the wiring diagram. But maybe that's the whole problem.

I'll go out and look.

So for the question above - should each post on the on/off switch have a wire connected to it?

 

[nickb857]

Are the lights themselves grounded. In the post above it says for the switch one is power one is relay and one is ground or something. If the gound is not connected try hooking it up anyhow. See if it fixes anything.

"The ground doesn't need to be hooked up on the switch unless you want the light to work"

 

[Apexdisco]

everything is grounded at this point.

I hear the switch click, but its way off what the diagram calls for, in terms of wiring location.

 

[traveltoad]

I don't know what you have for a switch. The third post may be for an internal light in the switch. Often, the wiring diagrams that come with relays are wrong. It should click when being switched on and off. The power feed (from the battery to the lights) just runs through the other two posts.

Make sure each component of your system works independently... then add one compentent at a time to the system. It will be easier to find where the bad part or your error is located.

 

[traveltoad]

everything is grounded at this point.

I hear the switch click, but its way off what the diagram calls for, in terms of wiring location.

So wire your lights through the other two posts. Take a hot lead from the battery (bypassing your switch) and activate the relay with that. Do the lights work? Is yes... you've wired the switch wrong.

 

[traveltoad]

everything is grounded at this point.

I hear the switch click, but its way off what the diagram calls for, in terms of wiring location.

As a side note... Hella relays work the way they are supposed to (in a logical sense) and the way the diagrams says they do. "Other brands" tend to work using adjacent posts... and it's up to you to figure out which two. It have found it is worth the extra $$ for a fused Hella relay. (Just my $0.02)

 

[Steve Rupp]

Here's my problem: you said the lights were working with just the switch before you put the relay in. You didn't need to do anything to the switch. The three terminals are power, switch (lights), and ground. You need to hook up the first two. The ground does not need to be hooked up for the lights to work. The ground is only completing a path to light up the switch. That being said, hook up the relay like I said (inline with the switched power from the dash switch to the lights plus powering up the relay and grounding it) and it will work. If you are still having problems, get a meter and try to figure out where the flow is going.

 

[Steve Rupp]

I wish I was there so I could just do it!

 

[Apexdisco]

I wish I was there so I could just do it!

LOL!

Sorry man, I just can't explain what's going on over here. I'm messing with again tomorrow.