In my 1992 V12 convertible my electric auxiliary fan does not work when driving the car. After reading various threads on the forum I used a jumper wire to bypass the temp switch on the fuel pump. The fan did not come on. I then used the jumper wire to jump the relay and the fan did come on. This led me to believe the relay is my problem. However, in playing around with it I noticed that if I jump the relay the fan will come on even if the car is off and cold. Does that make sense? I assumed the power should only get to to the relay when the car is on but this is my first time even learning that relays exist so admittedly its just an assumption.

If it IS the relay does anyone know what relay should be used to replace it? The one in the car is black, not red as it seems the original should be and I am not sure its the right relay.

 

Not unusual for a relay to have a constant 12v voltage supply. This is what feeds the circuit/device being power-up by the relay when it (the relay) is 'triggered'. Depending on the application/use, the triggering event may be a ground signal or another positive voltage signal.....the latter often being dependent on 'key on'.

Cheers
DD