how do i wire this relay?

Check the section on Relays as in https://www.the12volt.com/relays/relays.asp Relays are just switches that turn on/off by giving a voltate to a coil (energizing). The coil is always between pins 85 and 86. Input (or output, depending on your use) is always pin 30. You wire 87 and 87a depending on your requirements. (This a SPDT relay) you can also get SPST relays. However if you doubt, better get the SPDT since it can be used as a SPST too by leaving pin 87a as a dummy.

I see your relay has pins 30, 31b, 15 etc. I did not realise that before. Who manufactured the relay you have? Do you have any part number or something?

mine only has  terminal 30  31b  15....thats it  

its a gm part from a junk yard    90 464 777  12v 38697

That's interesting. A relay must have at least four connectons, two for the coil and two for the switch that you want to use to break a continuous line. Unless there is a screw or soemthing holding the relay, which is one of the "connectors". I will check and see if I can find any info on your part.

I am not able to find any info on it, but here's what you can do. If you have a DMM or VOM, check two connections out of the three at random until you find two that have some resistance. Not zero/short, nor even infinity, but some resistance. This would be the coil. Now that you know the pins for the coil, try giving it 12 volts from a transformer/battery charger or whatever you can get some voltage from, doesnt matter if it is DC or AC. You should also hear a click sound while energizing your relay and de-energizing it. Check other connections to see what comes on and off with the VOM or DMM.     My thoughts are since you have only four connections, the fourth missing/hidden wire could either be one of the relay coils (such as a common wire for Ground). If that is not it then a metalic part of the relay. I can only guess, and i repeat "guess" that 30 and 15 are the coil, but dont take my word for this. Check it with the meter.

Hi, Terminal 30 - Car Lights (+12v with lights on) Terminal 15 - Ignition (+12v with ignition on) Terminal 31b - Door Courtesy Light Switch Hope this helps.

thanks

what did you use the relay for? buzzer or lights or other?