I would appreciate some help with the XJR electric fans. I'm installing the drivetrain of an '01 XJR into a Mark 2 and have a problem with the fans. The AC condenser and supercharger intercooler fit fine forward of the radiator, but I think the fans are too wide for good air flow (see pic). I thought a single large 2 speed fan would be the fix until I studied the XJR wiring schematic. It looks like a control unit places the 2 fans in series to run at low speed (each sees 6V), and in parallel to run at high speed (each sees 12V). All of the aftermarket 2 speed fans appear to have separate low and high speed windings, each of which requires a separate (switched) 12V feed. With the XJR wiring each circuit (high and low speed) sees 12V at either speed. Is there any way I can make this work? Thank.

 

Look at the page above the schematic itself and the two control pin definitions are there. They are separate for high and low speed fan activation, active ground.

Therefore, you have three choices.

1) use two new relays driven by the ECM pins for high and low speed ensuring that the new relays have voltage spike damper diodes installed to protect the ECM when switching.

2) use the existing module by cutting the wire(s) that gang the output and driving the fan inputs for high and low speed from the now separately functioning relays.

3) keep the factory two fan setup. it will probably work best. don't forget, as long as the fans can drive air it does not matter if the inlet is directly in front of the fans as long as it is supplied with a volume of air from a plenum. the space between the fans and grill are essentially a plenum.

As you can see, #3 is the best option. You don't have to have direct flow, you have to have sufficient flow. And the twin fans offer better coverage as well as redundancy.