I have a 2000 Grand Cherokee.
It has started overheating when stopped at a red light or stuck in traffic.
I replaced the Thermostat and the Temp Sending Uint, still overheating
Then I noticed that the Elec. Fan is not coming on, even with the A/C.
I ran wires from the battery to the fan and it will come on so i think the fan is still good but im not sure what else to do.

I checked Autozone online and they have

i also have a Haynes book, and it says nothing about any of these parts.

 

Check the relay and see if it is getting power and functioning.

 

I spent the whold day trying to find out where the relay is.
I found it under the headlight, now how do i test it

 

Check and see if there are any fault codes stored. Retrieving codes: http://www.wjjeeps.com/faultcodes.htm

 

There is a 40 amp relay in the PDC under the hood.
http://www.wjjeeps.com/misc/power_dist_ctr_02.jpg

 

Here's a site for your Jeep with lots of info. http://www.wjjeeps.com/index.htm

 

it's your relay,extremely common problem. Do a search on this site,there are hundreds of threads about it http://www.jeepsunlimited.com/forums...splay.php?f=21

 

Problem solved!!!!
I replaced the relay under the pass. headlight and the fan now comes on with the A/C.