Auxiliary Fan 98xj Code p1491 Help please

I almost never post and I did read as many threads about the aux fans so if I missed I apologize.
What I have done:
Checked all fuses all goog
Checked and swapped around relays at PCM
Jumper-wire on Thermostat sensor nothing fan still wont work
Compressor kicks in fan speed in side not working though ( this has been down for a while and the fan Auxiliary was still working.
Freon fully charged

My shop manual shows a "relay NO. 2" yet I cant figure out where it is located?
Thanks in advance to any and all for your help.
Charlie
Ps I have no problem making a $$$$ donation if we can get:flame: this fixed

With the engine running unplug the connector that attaches to the coolant temperature sensor; this should cause the auxiliary fan to run as a test.
If it doesn't then disconnect the connector at the fan and determine which is ground and attach wires direct to the battery to determine whether its the fans motor being bad or the circuit going to the fan.
This way you know if its mechanical or electrical.

Just be prepared to see a code for the Coolant Temp Sensor after you unplug it if either the ignition is on or the engine is running.

Thank you, I will do today after work. I did use a test light with engine running AC on to see if voltage was going to the fan and nothing. I tried the removal of the connection to the CTS, and the fan did not come on.

My shop manual shows a second relay, I stink at any sort of electrical as I am colorblind, so I have to have the wife tell me which colors are which.

Thanks Charles for all the help!!
Charlie

UNCC_99XJ said:

Just be prepared to see a code for the Coolant Temp Sensor after you unplug it if either the ignition is on or the engine is running.

Click to expand...

The trouble code should clear after a few cycles of starting the vehicle once the connector is reattached.

OK Fan works fine hot to battery. Are there any relays inside at the junction box that would control the fan? Thanks again to all.

Yes, one of the relays controls the fan. It should be printed on the underside of the PDC lid.

There are only two places that relays are located on the 98. The PDC in the engine compartment and the junction block behind the kick panel to the right of the glove box. Sorry but I am on travel so I cannot give you specifics as to the exact relay.

Swapped all 3 Relays at the junction box and nothing.....thinking about buying an adjustable temp control switch and going directly to power.......I want to fix this correctly but this is about to cause the throwing of tools meters and the wife...Ok not the last one. Thanks again....is to early to start drinking?

i have all data at home.
It gives pictures, and locations of fuses, relays, and other locations like grounds, and splices.
Give me a call, and i will walk you thru it. five fyve nyne sevin seven six nine too threeee nyne

Try here:

http://www.lunghd.com/Tech_Articles/Cooling/Electric_Fan_Diagnosis.htm

This will either help or further infuriate you.

Use at your own risk. YMMV......:thumbup:

Lunghd's info isn't any help on a 97+; the relay is in the PDC.

mavsdad said:

Swapped all 3 Relays at the junction box and nothing.....

Click to expand...

Someone with a 98 please verify this, but shouldn't there be 4 relays? Starter, fuel pump, ASD, and the fan relay?

Not sure if it's the same for a 98, but here's the PDC layout and breakdown of what relay/fuse is associated with each position. The PDC did change over the years, but I'm not sure when, so this might not be any help either. This is taken from the manual for a 97.

http://i266.photobucket.com/albums/ii244/AHhub/forum stuff/DSCF5572.jpg

http://i266.photobucket.com/albums/ii244/AHhub/forum stuff/DSCF5571.jpg

hubs97xj said:

Someone with a 98 please verify this, but shouldn't there be 4 relays?

Click to expand...

Yes, my '98 has 4....

Thanks to BIG BLACH XJ
He spent over an hour on the phone with me trouble shooting the issues, and man I had no idea what I didnt know. Not fixed, but he had me jump several elect. items: Relay in PCM to batt, relay different slot in PCM relay slot to fan and on and on and on. This guy is the sharpest Jeep guy I have ever spoken with, if he posts anything I would listen.

Too much to type but we/he figured out it is either power from the ignition switch to the tstat sensor is too low 5.3v cold key on engine off. At running temp of 195 .93 volts.

He also discussed with me since the engine had severely overheated, that "Diodes" are probably fried in the wiring harness. I am trying to share as best I can, this guy had all the schematics and walked me through everything, MOST IMPRESSIVE!!!

I have a local guy former guy coming by Monday to take a look...as being color blind I have done all I can.

Thanks again to all, going to donate now.
Charlie

Im having the same problem, and the 15 amp fuse keeps blowing everytime... please help!!! I even changes the ECM... what could it be?