Cooling fan

[TURBO200R4]

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.

 

[TURBO200R4]

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.

 

[Nat67]

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.

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 !

 

[Nat67]

@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 ?

 

[TURBO200R4]

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.

 

[Nat67]

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.

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 .

 

[TURBO200R4]

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.

 

[Nat67]

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.

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 !

 

[TURBO200R4]

also some electric motors will stop at a bad spot and then not work
good luck and keep us posted.

 

[Nat67]

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 !