short version of a long story...radiator fan won't go off; ordered new relay; turned fan off by pulling the breaker... wanted to go riding, so installed breaker, went out, fan stopped somewhere, AC stopped cooling and engine overheated; got home, tested fan fuse, replaced relay under headlamp, shorted temp sensor; added freon....tested e fan, OK;; will not come on, engine overheats, AC won't work.... seems like its all related, but I have tried everything I know... and thoughts on what to test or change?

 

Yeah. Your username is putting a jinx on you

 

What means "shorted temp sensor?" The PCM controls the fan by reading the temp sensor and sending a pulsed or steady signal to the fan relay. If it's not getting a temp signal, it's probably confused. The temp sensor is a variable resistor and needs to be within a normal range to function.

 

well, the sensor wires were attached to the sending unit for all tests, as a last resort, I pulled the harness off the sensor and jumped the two wires, simply completeing the circuit. Can I test the sensor? and how? thanks, Bob do you know or have a theory as to how all of these cascading maladies are connected?

 

Just unplugging the sensor on later model cherokees will cause the fan to come on. Shorting it you may have blown a fuse in the circuit now.

BTW this thread is for the Grand Cherokees;-)

 

2002 4.0 automatic

 

That's a 5 volt circuit coming directly from the PCM. I don't think there's a fuse involved. Either 0 ohms or infinite ohms is going to confuse the PCM.

You can test the sensor with a multimeter set on ohms (resistance). It's often marked on the meter with the Greek "Omega" symbol. Test JUST the sensor with the connector unplugged. It should read about the same as the IAT sensor because they are manufactured the same way. If you check the temp sensor when it's installed, the resistance will depend on the current temp of the coolant. The IAT will vary depending on the temp of the air inside the intake manifold.

Just for instance, using a scanner when the engine was running at 210*, the outside air was 60*, and the IAT read 154*.

 

lol.... he's talking about a Grand Cherokee.... 'cause unless he's driving a Liberty in Europe, he's not driving a 2002 Cherokee

 

Right, I was just giving him a bit of grief about calling his vehicle a misleading name. It's a fancier cherokee, with even Grander problems...lol

 

That's a good one man! And very true!

 

So I've got a '96 ZJ that runs and drives great, the frame rail is rotted through so I'm selling it off for parts. Friend is thinking of buying the 5.2 to swap into his YJ, how much is it worth? Also, he's hoping to find an NV3500 to use as the transmission, but how much would the 44RE be worth? 160K mi on them.

 

[QUhttps://www.cherokeeforum.com/f5/power-windows-passenger-help-234494/#post3374808OTE=rcguymike;3202661]I'd like to start a sticky and get some Grand Cherokee masters in here like the Cherokee section has!

This thread is for all those who would like to ask something tech related and don't want to start a new thread or hijack someone elses, and for all those tech related questions you happen to ask in the big off topic threads. Me and some of the older members will answer every kind of question as long as it is TECH and polite.
P.S. for the newbs: stupid questions don't exist, there are only stupid answers. Feel free to ask whatever you want. "What is a Jeep?" is a good question....

If your question is very common (eg: lift) please DO A RESEARCH FIRST and if you don't find the answer come back here, 75

 

04 gc rewired, where does this light blue wire go? Passenger side not working
[QUhttps://www.cherokeeforum.com/f5/power-windows-passenger-heilp-234494/#post3374808OTE=rcguymike;3202661]I'd like to start a sticky and get some Grand Cherokee masters in here like the Cherokee section has!

This thread is for all those who would like to ask something tech related and don't want to start a new thread or hijack someone elses, and for all those tech related questions you happen to ask in the big off topic threads. Me and some of the older members will answer every kind of question as long as it is TECH and polite.
P.S. for the newbs: stupid questions don't exist, there are only stupid answers. Feel free to ask whatever you want. "What is a Jeep?" is a good question....

If your question is very common (eg: lift) please DO A RESEARCH FIRST and if you don't find the answer come back here, 75

 

Is there a reason you keep attempting to quote the verbiage from post #1 in this thread?

 

Just a noob,sorry!