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  #1  
Old October 27th, 2019, 17:03
ChipsXJ ChipsXJ is offline
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Is this an electric fan MOD

Is this an electric fan MOD to make the fan run constantly?


The electric fan comes on when the ignition key is turned on and runs constantly until the ignition key is turned off.


I think I verified that this added relay is a bypass for the electric fan.
When the added relay is disconnected the electric fan does not come on.
When the relay in the PDC is removed the electric fan des not come on.
We have replaced the sensor in the thermostat.
I have replaced the relay in the PDC.


Since it does work with the added relay....does that mean it is the ECM and it needs to be replaced?


When the AC or defroster is turned on the electric fan should come on, right?
2001 XJ.
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  #2  
Old October 27th, 2019, 18:03
tech1001 tech1001 is offline
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Re: Is this an electric fan MOD

How do they have the wiring from the added relay run yo the fan , did they cut it off the factory wiring ? or did they just splice into the factory wiring ?
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  #3  
Old October 27th, 2019, 18:11
puredrive puredrive is offline
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Re: Is this an electric fan MOD

I believe the AC electric fan only comes on at 218F on the 2000&2001 XJs
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  #4  
Old October 27th, 2019, 20:26
ChipsXJ ChipsXJ is offline
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Re: Is this an electric fan MOD

they connected it into the PDC somewhere.....I have not pulled the PDC to see where....but I am thinking it is tied into the wiring for the relay in the PDC.
2 wires come off the PDC and connect to 2 terminals on the added relay and another wire from the relay to ground. I don't appear to be able to add pics to my posts.
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  #5  
Old October 27th, 2019, 20:50
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Greenz Greenz is offline
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Re: Is this an electric fan MOD

Quote:
Originally Posted by puredrive View Post
I believe the AC electric fan only comes on at 218F on the 2000&2001 XJs

Correct. Had my 01 since 03. The only time the electric fan has come on is when it gets really hot over 215ish.
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  #6  
Old October 28th, 2019, 06:18
ChipsXJ ChipsXJ is offline
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Re: Is this an electric fan MOD

Thanks - I will disconnect the 'extra' relay and see if the fan comes on at temp.

IF, the fan does not come on at temperature....is there anything else I can look at it or is it
most likely the PCM//ECU at this point?
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  #7  
Old October 29th, 2019, 16:22
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Rainman Rainman is offline
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Re: Is this an electric fan MOD

the pcm will earth the control circuit of the relay whenever it wants to turn on the AUX fan.
it should come on around 104*C and also when the AC clutch is engaged, during normal operation.
If the coolant sensor is disconnected (or the circuit is bad) the AUx fan should run constantly whenever the engine is up and running.
to wire in a manual switch, a relay often integrated into the power circuit of the original wiring, as opposed to switching the control circuit that the pcm uses as it will cause a MIL light on OBD2 xj's. OBD1 will log a code but not switch the light.

good luck with it.
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  #8  
Old October 30th, 2019, 07:01
ChipsXJ ChipsXJ is offline
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Re: Is this an electric fan MOD

@Rainman - What I am hearing you say is that it is probably the coolant sensor (the one in the thermostat housing) circuit that is bad?
I have replaced the sensor already.....so it would be the wiring between the sensor and the ecm that would be suspect?

Thank you all for your replies.
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  #9  
Old October 31st, 2019, 03:55
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Rainman Rainman is offline
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Re: Is this an electric fan MOD

If that was the case it should be storing a code.



god knows what bubba has done to that jeep.
if the fan is comming on and off with the ignition switch, thats not the PCM beeing upset with the coolant sensor. if that were the case the pcm would switch on the fan AFTER the engine cranked, fired and was running.
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  #10  
Old October 31st, 2019, 03:56
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Rainman Rainman is offline
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Re: Is this an electric fan MOD

If that was the case it should be storing a code.



god knows what bubba has done to that jeep.
if the fan is comming on and off with the ignition switch, thats not the PCM beeing upset with the coolant sensor. if that were the case the pcm would switch on the fan AFTER the engine cranked, fired and was running.
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