Need electrical relay help FAST!!!

I got myself into a bad bind. I used projectxj.coms headlight harness to reqire my headlights. My problem is this, the relays I have are both 40 amp/12 volt (no prob), but they have a pin 87 and a pin 87a. Is pin 87a a constant on? I get power to one headlight when the key is out of the ignition.

87a - NC
87 - NO

NO = Normally Open. Unit will close the circuit on "make."
MC = Normally Closed. Unit will open the circuit on "make."

So, with the relay coil not engergised, you will see output power at 87a, but NOT at 87. Energise the relay coil, and the reverse is true.

There are variations that do not have the "87a" terminal - they are NO units that are used just to turn a circuit "on". The standard relay is designed to either "make" or "break" a circuit - or to "switch" one.

There is also a version with two "87" terminals - it will supply power to two separate circuits when "made."

I haven't finished my harness design yet (had houseguests this week, which blew everything all to Hell) and when I finish putting a dresser back together I'll get back to work on it (just finished putting the shower back together...)

5-90

In a 5 post relay, 87 & 87a are the output "choices". When terminal 87 is not connected (and delivering power) than 87a is. So the 87s are your load (output connection), the 30 is your line in (12 volt +) 86 is the trigger signal and 85 the trigger ground (to complete the circuit).

So when the relay gets voltage on terminal 86 (trigger) it closes the circuit from 30 to 87. When this voltage is not present, the circuit is closed to 87a.

If you are not using 87a, it can be blocked off, it is for applications where power goes to "either 1 or the other" such as high/low beams where the low beams turn off when the high beams go on.

Pretty much any relay of this type works the same way. A 4 post relay has a dead end in place of 87a so the circuit is open w/ no trigger signal.

Using it for a headlight harness (which is what I'm doing), could I splice both low beams to the one 87 and the same for high beams? Or is that going to blow something/damage anything?

I don't quite understand what you are doing, and why you are modding the headlight relay (are you replacing the headlights with offroad lights?).

To use 2 relays, (one for each side) use the trigger signal input- in other words splice the wire coming from the switch to both relay 86s. Properly fused of course.

I believe the stock setup is spliced from one common relay output, the 2 headlights are wired parallel and the wires from the right side meet the wires to the right headlight at the right headlights own socket.

I don't know what youre trying to do though and what amperage its going to draw.

I have 2 five pin relays. Each has a 30, 86, 85, 87, 87a. Since the 87a is a constant on, I can't use this since it'll be continually drawing power and lighting the headlight. I'm rewiring the headlight so I can safely use 100/80w headlight. Would it be safe to simply splice both high beam wires together and run them from the normal 87 pin, and the same for the high beams on the other relay (one relay for high, one for low, both getting fused power)?? Or is this going to damage something?

Yep - that's the way to do it, unless you're using something REALLY big for headlights!

5-90

You guys rule! Thanks so much for the quick responses. I had no headlights and had to be somewhere in an hour. Saved my day. Thanks again!