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The radiator fans run at full speed during ignition-on and during driving all the time (A/C is off).
(I've tried a second CFM, too. Same behaviour.)
I've checked:
Coolant sensor: cold, diagnosed temperature is plausible
Air intake sensor: cold, diagnosed temperature is plausible
Fuel temp sensor: resistance ist plausible
Evaporator temp sensor: resistance ist plausible
Discharge temp sensor: resistance ist plausible
A/C pressure sensor (A/C off): sensor wire is at about 1V (according to wiring scheme 0 to 5V)
Engine Oil Temperature sensor: resistance ist plausible
A/C runs ok, if I activate it for test purposes.
No DTC in ECU. (At the moment I'm not able to read Climate Control Unit and Tramsmission Control Unit.)
Why ECU don't regulate the fan assembly? (The waveform is always the same.)
Wiring is 100% ok, because CFM delivers 12V level on control wire and ECU pulses it to ground for realizing the PWM pulses.
This measured PWM waveform (about 93% high, and 7% low) means full speed or means low speed?
I suppose full speed. (?) CFM: PWM control signal (generator at 15.30V shortly after motor start - later falls to 13,xxV)
Hi Catfondler,
I have the exact same problem with my Jaguar. Fan starts at high speed and stops (after a few seconds) when I switch off the car. Just wondering if you have found a solution yet? Took the car to a mechanic who specialises in Jaguar. He was not able to fix it.
Thanks
Unfortunately i haven't resolved the problem until now.
The automatic transmission fluid temp sensor doesn't seem to be the cause.
I'd changed the defective (water corrosion due to interior cleaning by a cleaning service provider) climate control modul (incl. SDD diagnostic tests), the defrost flap is now running but this wasn't the cause, too.
But my "repair project" is still running...
Did you check the signal wire (white blue) / it's PWM control signal at the fan control module on the fan assembly?
Last edited by catfondler; 06-02-2022 at 02:04 PM.