if it works, take it
apart to finde out
AO Silver Member
Join Date: Dec 2008
In the pdf you see the thermo switch (sensor) that is fitted in the radiator, it has three pins, one pin pulls low speed relay to ground and one pin pulls high speed relay to ground, and third pin goes to ground.
Disconnect connector from the sensor and measure, there should be voltage on two pins, if you do not have voltage on one or both pins then you have problems with fuse(S) or wiring or the relay(S) itself, high speed or low speed or both on the control(energizing) side of the relay(s).
If you have voltage on the pins in the connector, earthing one pin at a time, and the fan will start either at high speed or low speed and if the fan starts then you have a faulty thermo switch or problems with the ground connection to the switch.
If the fan does not start when you earths one of the pins of the thermo switch connector (if you have voltage on them) then the fault lies on the fan side, low speed fan: fuse, low speed resistor on the radiator,
wiring or relay, high speed fan: fuse, wiring or relay.
That the fan went started briefly at a 'higher' temperature point towards that the low speed resistor on the radiator could be faulty, but be aware that the temp gauge sensor is located on the engine's hottest place and the thermo switch are located on the radiator's coldest place, so the correlation regarding temperature between the two is not the best.
Also note that when you measure if you have voltage to the fan so can you not measure between the wires (red, brown) you must earth one probe to the engine or any other earth point because you have voltage in both red and brown wire.