can someone please help explain electrical relays

[tphsmith]

I am working on putting an LT1 into my 72 1/2 ton, now its down to the wiring can someone please explain to me how the fuel pump relay and the fan relay need to be wired correctly. Yes I have had the wire harness from the LT1 modified. and the fuel pump relay and the fan relay I am not sure how to wire them up the relays have 2 wire coming off of them one wire is white the other is black. is the white wire hot? and the black ground? does the white wire go to the positive side of the the pump and the black right to frame ground?.. please guys please clear my confusion up for me please

[Hart_Rod]

I'm pretty sure you can wire it either way. Post a picture of the relay.

http://www.the12volt.com/relays/relays.asp

[Orange]

Relays are usually used just to relay power to something, but I don't see how it would work with just two wires with one being ground and one being + out.

I am not an electrical expert by any means, but I would think the relay would have to receive a signal from somewhere to do any good at all.

So, one of the wires has to be an input, and one has to be an output. With a two prong relay, it would be really easy to test with a voltage tester. Just give one side a 12v charge and OHM the other side to see if it has power. If not, then the other side should/will. The side that has power coming out is obviously your output.

In your case with the fan/fuel pump...I would suppose the output would go to the + on each those accessories. The can't get their power until that relay is turned on.

Now, what turns that relay on is on the other side of it, and that's all you need to figure out. That's the original thing from the donor car. Too bad I don't have the Camaro anymore.

DLB

[tphsmith]

Im sorry I did not give all the detail there are other wires already wired into the relay from the main wire harness, the wires that are coming off the relay in question are the ones that I am supose to know where they go everything else has been wired into the wire harness. so because I have never wired a relay before in my life, I am needing to know if the white wire coming out of the relay in position 87on the relay does this go to battery positive side and the other wire is black position 30 on the relay does this go to frame ground?. the other 2 wires are prewired into the wire harness, Hart Rob the web sight I need to look into your help of the sight but I was hoping you guys were pretty familiair with the relays.. can I please get more feed back please, Id like to get this wired in tonight. the rest of the numbers on the relay are 86, 85, 87A,

[Hart_Rod]

What interior harness are you using? Fuel pump relay should be triggered by your fuel pump signal from your interior fuse panel. Fan relay should be triggered the same way. Don't know if that helps or not. Take a look at this manual from painless:

http://www.painlessperformance.com/M...Supplement.pdf

[tphsmith]

thanks Hart Rod, I will post pics tomorrow afterwork, Im realy trying to stay with original chevy wire harness that was in the truck and tying into the original with the LT1 harness, there are like 12 wires that I need to tie into my harness that is original with the truck. its just the relays are realy confusing me because Ive never messed with them yet, but listen Im very appreciative of your help with little help from me what Im doing. but i will try to explain for its more clear. its just electrical is slowing the project way down.

[Hart_Rod]

Originally Posted by tphsmith

thanks Hart Rod, I will post pics tomorrow afterwork, Im realy trying to stay with original chevy wire harness that was in the truck and tying into the original with the LT1 harness, there are like 12 wires that I need to tie into my harness that is original with the truck. its just the relays are realy confusing me because Ive never messed with them yet, but listen Im very appreciative of your help with little help from me what Im doing. but i will try to explain for its more clear. its just electrical is slowing the project way down.

No worries! I think I figured out what you're doing. Look at this diagram:

[jeffspower]

Take a few minutes to figure out what a relay really does, & how it works. 85 & 86 go to the pull- in windings. One is ground, the other is powered up to turn on the device (when the device is controlled off 87) or to turn it off (when the device is controlled off 87a). The winding circuit doesn't carry any load. It doesn't matter if 85 is ground and 86 is the "trip wire", or vise- versa. The internal coil it powers up could care less, & works the same either way. Some computer controlled relays are ground controlled, instead of power controlled. 30 is your device power supply (in a power switched circuit thru a fuse or circuit breaker) or device ground supply (in a ground switched circuit) that carries the load, . 30 & 87 is a normally open switch. 30 & 87a is a normally closed switch. I hope you don't find this too confusing. Once you can grasp how it works, it will be easy to understand. Then all you have to know is how each device is controlled, power or ground.

[jeffspower]

Originally Posted by Hart_Rod

No worries! I think I figured out what you're doing. Look at this diagram:

Yep, that looks right. The orientation of of 30/ 87 (or 87a) doesn't matter either. Flip flop them either way.

[Omnivec]

First time sending a pic. excuse its crudeness it take whole 15 mins to make.