coil mod relay power

I have the five prong auto relay that has two outputs, one for the coil mod I did, and I want to know if I can wire up a license plate light to the other output since I relocated my license plate to the side. Will this cause me to lose power to the coils or will I still get enough power though the relay to get fat spark?

Can I even do this?

Thanks!

There are two voltage-out pins on a five pin relay. 87 and 87B (or is it 87A?)... anyway, you could run the tail light with no problems I think.

No, No, NO!!!!
On a 5 blade, the other output is on until power is supplied.
So when you turn the key ON, supplying power across 85-86, you close the circuit between 30/87, and open the circuit between 30/87A. But when you turn the key OFF, you open the circuit across 30/87, and CLOSE the circuit across 30/87A. So if you have a 5 blade relay, for heaven's sake be careful what touches 97A, or you could at least have a very dead battery, and at worst have one h### of an electrical fire.

Yikes!

Okay so I should connect the 87 to the coils and cap off 87A?

Good thing I asked I guess

Post edited by: 77Davo650, at: 2007/01/25 15:32

Bingo! Yes, insulate the 87A terminal.

The 5 pin relay I have has two #87 pins. One I used to power the coils, the other I used to power the IC Igniter.

There are many different types of 5 prong automotive relays so you will have to check to see if both of the 87 prongs are hot when the relay is powered up. Use your VOM. The ignition only uses about 10 amps and the new plate light uses another 1 or 2, so as long as you have a 20 amp or larger fuse between the battery and the relay ( you do have an in-line fuse!?! ) you should be fine.

Ride Well,
Jon

Wow... I have used the alternate 87 power out in the past and the 87 and 87A are identical. I have used several brands of relay as well. Guess you could always trigger the relay and measure the power on both 87 and 87A and see if it bears out my statements.

OK, here's what I KNOW.
Every supplier of electronic widgets (DigiKey, Mouser, etc.) that supplies schematics of said widgets shows a schematic for a 5 blade auto relay with an 87 and an 87A blade wired so that when you turn the key ON, supplying power across 85-86, you close the circuit between 30/87, and open the circuit between 30/87A. But when you turn the key OFF, you open the circuit across 30/87, and CLOSE the circuit across 30/87A.


I know that when I have used one of these relays as a car headlight dimmer relay, with high beams wired to 87 and lows wired to 87A, when the switch I have wired to be the dimmer is in the [off] position the low beams are on, and when I move the switch to the [on] position the low beams go off and the high beams go on.
Now, I have never run across a 5 blade that has two 87's so I guess I have something else to look for at the auto supply store.

Post edited by: pstrbrc, at: 2007/01/26 10:29

I understand there are many different relays available. I found a link with different wiring diagrams of relays. Some have double 87 pins that are both powered, some have 87a and 87b that alternate power. Heres the link. If you have an unknown relay you can only measure it with a meter I guess.

www.vehicle-wiring-products.co.uk/VWPweb2000/relays/relays.html

Okay, I have what may be a stupid question but I need to ask because I'm getting frustrated.

I ordered the 5 pin relay and pigtail that Wired George has linked in the instructions for the coil mod on his website and followed the directions to a T in wiring up the relay mod. After running everything appropriately (with pin 87 wired to the coil power) I got no power to my coils. When I plugged the stock set up back together bike fired right off. Do I need to run 87 or 87a to the power of the coils? The colors on the pigtail I received are as follow:
30 = Blue to starter solonoid with inline fuse holder
85 = Black to main chassis ground
86 = White to harness where coils originally plugged in
87 = Creamy white (split to coil power)?
87a = Red (split to coil power)?

Any help would be muchly appreciated!!

Usually the #87 lug goes to the coils, but it depends on which relay you have. You could check both #87 and 87A with a meter to see if they both have power, or are reversed switched like mentioned above.

These diagrams show how I did mine, but my relay has two #87 lugs, for driving lights: