The problem with the relay is cold solder joints. If they had been soldered properly in the first place, they would not have failed. What happens is the pin that fits through the hole in the PCB does not get hot enough to adhere the solder properly. You'll notice that the pins where the problem exist are the largest pins with the body of the relay acting as a big ole heat sink when the soldering takes place.
Corrosion of the copper on the un-tinned (non-soldered) pins and holes in the PCB is what causes the open circuit to occur.
I have repaired my Idle Speed Control Module failure by resoldering its joints as well. Next is the cruise control module, which is flakey.