Mechanics

RADIATOR FAN NOT WORKING

2002 Jeep Liberty

Engine Cooling problem
2002 Jeep Liberty 6 cyl Four Wheel Drive Automatic 100k miles

02 jeep liberty fan will not kick in. Fan works when jumped to 12v source so fan is good. It all started when 4 pin wiring harness that connects to relay had burnt up. Looks like the harness connector was arcing @ the relay connection. I replaced harness with kit from chrysler. Didn't fix the problem. Replaced relay thinkin it could be bad. Still not workin. 40 amp fuse is good so I'm not sure what to check next. I'm an electrician so I have tools and skill to check things. Just don't know what to check next. Any suggestions would be great.

Thanks in advance
Avatar
Wahoos
June 26, 2010.




I have posted below the entire cooling fan wiring circuit to help you.. since the relay , fuse, wiring and fan have been ruled out..all that leaves is the computer (PCM), but you can take a look at the circuit for yourself below..


http://www.2carpros.com/forum/automotive_pictures/261618_Noname_2369.jpg


Bluelightnin6
Jun 26, 2010.
Thanks for the diagram, it helped me troubleshoot a little more. I was hopeful for a bad splice on the harness but I put a jumper between the power pins and the fan worked. I got continuity from ground pin and frame so that was good. ReSpliced pcm wire to make sure. But still doesn't work. I don't know how to further check pcm so I guess I'm stuck replacing the unit.

Tiny
Wahoos
Jun 26, 2010.
Is there anyway to find a pcm pin out diagram for 02 liberty limited? I pulled the pcm connector out and checked for continuity between connectors and got nothing. I would like to know which pin it is so I can run new wire from pcm pin to wiring harness.

Tiny
Wahoos
Jul 8, 2010.
Wow. Might need a magnifying glass to read that diagram. I found A light green wire in the pcm wiring conn but it must be a different wire. I cut into the split tubing to trace it but it does not tie into the the fan relay.
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Tiny
Wahoos
Jul 8, 2010.
So I'm still trouble shooting this fan in hopes of not replacing the pcm and to make sure that is indeed the problem before I purchase a new one.

So here is where I stand now. I pulled the conn from the coolant temp sensor (cuz something has to tell the pcm when to start the fan. Right?) And I jumped those two wires. Fan comes on soon as start the jeep. Gauge doesn't read but fan now works. Well I replace that sensor but that damn thing still doesn't come on! How could that be?

Any suggestions would save my hair from being pulled out : -) thanks

Tiny
Wahoos
Jul 21, 2010.
The fan is not supposed to turn on until the engine reaches 170 degrees, so it shouldn't turn on when you start up the jeep. Are you waiting until the jeep gets hot?

Tiny
Houstoib
Jul 31, 2011.
If your Liberty is anything like mine that fan may not come on until a good hot summer day. Mine doesn't come on at ALL if the outside temperature is below 75 or so.

Tiny
Steve W.
Aug 5, 2011.

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