Originally Posted by Idle

Testing one of the four prong relays is easy. First you pull the plug on the relay and find out if you have power to the relay.

Just ground out the negative probe of your voltmeter and then poke the positive probe into the socket holes. One at a time.

Oh, yeah, set your voltmeter to the 20v dc setting, or in that range depending on what your meter has for settings.

Turn on the key to power up the system. Out of the four holes in the socket one of them should test at least 12v dc.

So now you have power to the relay.

Next remove the relay from the car. Our of those four prongs one is positive, one is negative, and two are volts in and volts out.

You know which is the 12v positive pole. You just found it on the socket. So line that up with the prongs on the relay and hit it with 12v positive. (Run a wire over there from your positive terminal of the battery) One of the poles next to it is the ground. So run a wire from the body of the car or the engine block to the relay pole next to the 12v + and you should hear a click. If no click touch the other pole. You should hear a distinct click. If you are holding the relay in your hand you will also be able to feel it.

So now you have established the 12v + pole and the negative pole. Hook them up and after the relay has clicked (also known as 'pulling in') check for continuity across the two remaining poles. You should have continuity.

If there is no click the relay is bad. If there is a click and no continuity the relay is bad.

These can be redone if you carefully pry off the cover of the relay and clean the contacts on the relay. This would only fix the no click condition and maybe not even then.

If the relay is bad then start searching for another one. BE WARNED: These are not cheap. A tested used one might be a good way to go if you have to replace it.

And you should have about three of these relays on your car. Swap out a relay from another position and see if your windows work. Once you discover a bad relay then you need to find if this is your only problem. Swapping out relays on your own car is a fast way to find this out.