Cooling fan

all info based on wiring of the 07 type may be different on 2010
i just came across this thread.
u might want to do more checking before going after the temp sensor.
if i were checking it i would put 6 inches of wire (4 wires)between the relay and the connector so u could monitor what is going on. u should have power to two of them with key on. then the comp grounds the relay apply (when it reaches a certain temp) and the fan should come on. i am assuming that u know which terminal works the fan.
by grounding the wire that goes to the computer the fan will come on and if it does not come on then u need to check the circuits. decosse is much better at explaining these relays than i am. and if u r having trouble understanding u can ask me questions or pm decosse i am sure he will not mind.
 
ps if the computer is not grounding the circuit then the temp sensor might be the problem. i have bought resistors and used them to simulate the high temp,(by unplugging the connector and crossing over the connector with the resistor.
 
TURBO200R4 said:
ps if the computer is not grounding the circuit then the temp sensor might be the problem. i have bought resistors and used them to simulate the high temp,(by unplugging the connector and crossing over the connector with the resistor.
Click to expand...
Thanks so much for your input mate , a friend of mine who is a technician was showing me the ropes with a multimeter and did bring the fan on using the poles of the relay plug with the ignition on . He traced the problem back to the ECM not switching the fan and surmised , after testing the resistance of the coolant temperature sensor that , the sensor was more than likely the cause of the fail . I think that is what you have just explained to me ? I have to wait until I have all the kit together to start learning tune ecu , so I guessed whilst waiting I may as well replace sensor and thermostat to save having to come back to them later !
 
@TURBO200R4 , that idea of the resistor is brilliant , the manual I have gives a range of 200 to 400ohms . Am I correct in assuming that a resister of that rating will trigger the fan if bridged across the terminals of the harness plug ?
 
i could not find temp info on r3 but going by a Chrysler chart a 500 ohm resister would make the ecu think the engine was about 230 degrees and should turn the fan on.
of coarse u could get something close to 500.
 
TURBO200R4 said:
i could not find temp info on r3 but going by a Chrysler chart a 500 ohm resister would make the ecu think the engine was about 230 degrees and should turn the fan on.
of coarse u could get something close to 500.
Click to expand...
From the manual I have it claims the hot working range of the sensor should be between 200 - 400 ohms . My sensor was reading 652ohms with a hot engine .
 
if that is what it says i would assume it would have go below that to trigger the fan..
if u have a small 12volt light bulb u might measure it. i have a 12 volt test light that is 30 ohms i sometimes use it as a resister.
 
TURBO200R4 said:
if that is what it says i would assume it would have go below that to trigger the fan..
if u have a small 12volt light bulb u might measure it. i have a 12 volt test light that is 30 ohms i sometimes use it as a resister.
Click to expand...
It didn't drop below that figure so assumed sensor had gone out of range . I have a test lamp and will try that as a last ditch attempt to verify. Thanks for your help , I wish I wasnt so ignorant when it comes to the magic of electrical systems !
 
also some electric motors will stop at a bad spot and then not work
good luck and keep us posted.
 
Well , replaced the sensor which is a 10 min job . Only it's a 2 hour job to get to it ! Whilst there I replaced the thermostat and coolant hoses with samco to save having to go back down there again . Fired the old girl up and lovely jubbly. Coolant temperature sensor was the culprit ! Tomorrow I am doing a crash course in Tune ECU to reset the code .
Thanks guys for the help , especially the idea of putting a resistor across the fan switch . Touch of brilliance that was !
 
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