Ok it sounds like the relay is working. If you have a look at the schematic it shows a wire coming from the control unit from pin26 and see if a negative is coming out which goes to pin 4 on the relay. You can see on the relay the other side of the coil goes to a positive.
The problem will be either an earth from the C U or the wire is broken.
Show your auto elec the diagram. Should be able to work out simple control circuit wiring and work out if its at the C U
Thanks for the diagram Impul