Function of Rearmost Sensor on Coolant Rail, Series III XJ6

Rusty, The part number is EAC3762. Now, about it's function..... Gregory and I were trying to figure this out a few weeks ago but reached an impasse. I always thought it was the temp switch for the A.I.R. pump which allowed operation of the pump only on a cold engine. This theory was abandoned, however, when Gregory pointed out that a couple of his non-air-pump-equipped Jags have the same switch. I have been unable to find any reference to in the ROM and the parts catalog simply calls it a thermo switch with no further description. Doug Dwyer

Actually EAC3762 is a temp switch. It serves two purposes. Doug is right that it controls the operation of the air pump on a cold engine (on cars so equipped). But it also controls the operation of the electric switch on the evaporative control system, usually found on later cars just below the front of the air cleaner. The harness from the sensor branches at about cylinder #3, with two wires running around the head to the air pump and two wires running underneath the intake plenum to the evaporative control system switch. When it is energized the evaporative control switch closes off the vacuum source for the evaporative control system. When the engine warms up and the circuit opens, the switch releases, opening the canister to engine vacuum. Regards, Tom Golodik