Advice/Help on wiring driving lights on BJ42

[sbolduc]

(also posted on DTLC)

So I purchased to rubber cased driving lights and swapped out the 12V 55W bulbs with 24V 100W bulbs. I also purchased a switch and a Bosch 24V relay that will handle up to 30amps.

Of course I am stuck on the wiring. Here is what I have (and where I am at).

__________
| 87 85 |
| 87B |
| 86 30 |
--------------

The fellow at the shop informed me the following:
87 - Light
87B - Light
86 - Ground
85 - Switch
30 - Battery

So here are my questions:

1- I am assuming that I connect (30) to the positive post on the the drivers side battery, that is were all the other wires go
2- Does it matter which post on the switch (there are 2) I attached wire to (85)?
3- Can I ground it by bolting to the metal dash?
4- I have an inverter (IPC 20 I think) in the glove box, rather than run a wire back out to the battery, can I run a wire to the 24V input on the inverter seeing as it has a wire running from the Battery already. Or would this cause trouble.
3- The guy at the store told me that the other post on the switch needs to be connect to the battery as well. This seems odd to me and is what I worry about. He also said it could be attached to the ignition switch - where would I locate that?

What are your tips on this? I am sorry for the rookie questions, I really am learning - just not too quickly!

 

[Island Moose]

Well, you run 24v power from the positive post of the battery bank through an inline fuse, then into the 24v relay. You also run an ignition-switched 24volt lead into that relay (maybe tap off the stereo lead?). The second 24v lead flips the relay when the igntion is ON or ACC and opens the circuit from the battery through the relay, to your in-cab switch. From the in-cab switch to your lights (split the line to both lights.) Ground the in cab switch, the relay and the lights to the chassis. The dash is fine as long as it is unpainted metal (scrape it).

Switches are simple enough, attach the power and the ground, and if you have it reversed, change them or simple rotate the switch 180 degrees.

Take a new lead off the battery, healights suck big juice and so do inverters. Using them both may blow an inline fuse or worse, melt the wire.

You will have some fun trying to figure out which one of the wires in the dash is switched to the ignition, use a tester and a wiring schematic. It doesn't have to be a big amperage circuit, as that's what the relay is for...large amperage circuit controlled by small amperage circuit.

 

[Stone]

I answered your question on the DTLC list. Here it is for convenience:

Your relay marking should say "87a" not "87B".

Anyway, "87a" is a normally closed switch position, so you wouldn't wire your lights there. You would use "87" as the normally open switch that is closed when the relay solenoid is charged up.

Here's how I would personally wire it:
-Pin 30: is the source pin, so that goes directly to the positive pole of your high side battery.
-Pin 85: I would splice this to the (+)24v wire that is feeding Pin 30 to supply the relay coil with (+)24v. Splice it close to the relay for a neat connection.
-Pin 87: normally open switch position, goes to your lights.
-Pin 86: I would run one wire into the cab and to an ON/OFF switch. One pole connects to this wire coming from your relay, the other pole is a wire that goes to chassis ground somewhere under your dash.

Place an appropriate fuse inline on the wire coming from the battery to Pin 30 (whatever your lights require), and another fuse for the wire that goes to Pin 85 (usually 10A max) to protect the relay coil.

That's it!

Let me know if you are using an ILLUMINATED switch instead of a regular one, because that will have three pins in the back instead of two. One supplies the little light in the switch and will need to be wired differently. HTH. Cheers.

 

[sbolduc]

Diagram

How does this look? Should I follow this? Thanks again folks.

Wiring Diagram

 

[Stone]

That would work just fine. The only reason why I like to wire mine the way I do is that I personally prefer to have a ground wire going through my firewall instead of a hot wire...that's all. Here's a quick diagram of the way I wire my lights:

By the way, it doesn't matter which pin (85 or 86) you make positive or negative UNLESS there's a diode inline to your solenoid in your relay (which some models do). Cheers.