I’ve been looking at the circuit diagrams to try and figure out how the Radiator Fan control works. Much more interesting than Wordle etc.



Attached diagrams show what I think the circuit looks like for

1 – Ign Off

2 – Ign On Low Speed (Assumes the Jag fix for Low Pressure switch bypass is implemented)

3 – High Speed triggered by Coolant Temperature



Does this look right?

I’m happy to edit and republish the diagrams if you spot any errors.


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I'm getting hints that the fans run in 2 different manors maybe related to the 2 different relay modules ( white in color ) part #s ( the black X308 relay module runs a close but different circuit on the V - 8 out of the engine ECU that senses the coolant temp by a sensor and not thermoswitches on the X300 )

Both low or both high speed ( from reading others and Motorcarman )

Or mine / one high ( left ) or both high

I have a couple of white fan relay modules around and maybe both white versions

I have my original cut open as water got inside fusing the contacts ( previous owner had it mounted upside-down letting water to get in , you could shake it and hear water )

I once tried to decipher the bowl of spaghetti inside the relay module

The fans and relay module test is quick and easy

Paper clip in the radiator 3 wire coolant temp switch connector

Jump from one white wire to the black ground / one mode

Jump from the other white wire to the black ground / the other mode

Maybe the difference is if you have both white wires jumped to black ground ( both 86 and 100 C temperature contacts ) which I never tried ?

See item # 5

LNA6702 AA vs. LNA6702 AB / X308 is L J A6702AA ( black )

Genuine Relays For Jaguar Xj 1995 - 1997 (from 720125 To 812255) (x300) Classic | Jaguar Land Rover Classic Parts

 

Hi Brendan,

I think you are correct.
Looking at the wiring diagrams the fans operate is series (low speed) at lower temperature and in parallel (high speed) at higher temperature.