96 XJ Electric Fan not working

So I've been looking around on multiple threads and can't seem to find a straight answer anywhere..
My 1996 XJ's electric fan comes on with the AC and defrost with no problem, but does NOT come on when the operating temperature exceeds 218F like it should. I know I know, it shouldn't need to.. but it does and I would like the fan to kick on.
I've replaced the relay so it's not that, and the ECT sensor is less than 6 months old (maybe faulty?).
I'm thinking maybe there's a fuse somewhere that's blown that I'm missing, or the ECT sensor is faulty, or just wiring gremlins and I need to suck it up and splice in a manual switch.
Any advice would be appreciated.

On my 96,the gauge temp (sensor at the back of the head) will read about 15* hotter than the ECT sensor in the T-stat housing.
Have you checked the temp of the housing ?
You may not have reached the temp to turn on the fan....

Wayne Sihler said:

On my 96,the gauge temp (sensor at the back of the head) will read about 15* hotter than the ECT sensor in the T-stat housing.
Have you checked the temp of the housing ?
You may not have reached the temp to turn on the fan....

Click to expand...

No I haven't checked the housing temp. So you're saying there's a chance I'm not running nearly as hot as my temp gage makes me think I am?

Quailman said:

No I haven't checked the housing temp. So you're saying there's a chance I'm not running nearly as hot as my temp gage makes me think I am?

Click to expand...

YES .

yeah the sensor on the back of the head controls the gauge while the one in the thermostat housing will control the fan and that's the readin the computer uses.

if you unplug it and the fan kicks on, it works as it should. you will either have air pockets in the system which can cause a faulty ready, or like it was said the one on the back of the head reads hotter, so your engine is actually not at the temp the gauge says.

Best thing to do is spend the 20 bucks or so to get an IR temp gun. It will be useful for a lot of stuff, including this, so you can have peace of mind.

Wayne Sihler said:

YES .

Click to expand...

Do you think replacing the rear temp sensor that feeds the gage would help? Or is it just inherently innacurate?

My XJ came with the idiot light cluster,I wheeled it all over,never worried about the temp as it never puked any water.
Replaced cluster-and senders ,,,,now I was seeing how hot I thought the engine was getting,,Did all the up grades,Flowkooler water pump,thicker rad.HD fan clutch,ect. Did not change anything on the gauge still I thought it was Hot.Even went to an aftermarket sender and gauge...no change.Put a Snap-on Brick to monitor actual temps the engine was seeing-gauge was 210.Motor was 195....so now I dont worry.
Have seen 260 on the gauge has not puked any water -ever.That engine went 400,000 miles.
Dont worry until it pukes.

Wayne Sihler said:

My XJ came with the idiot light cluster,I wheeled it all over,never worried about the temp as it never puked any water.
Replaced cluster-and senders ,,,,now I was seeing how hot I thought the engine was getting,,Did all the up grades,Flowkooler water pump,thicker rad.HD fan clutch,ect. Did not change anything on the gauge still I thought it was Hot.Even went to an aftermarket sender and gauge...no change.Put a Snap-on Brick to monitor actual temps the engine was seeing-gauge was 210.Motor was 195....so now I dont worry.
Have seen 260 on the gauge has not puked any water -ever.That engine went 400,000 miles.
Dont worry until it pukes.

Click to expand...

Thanks for that, very relieving! Glad to hear I'm not the only one lol.
I did find out that the aux fan kicks on correctly though (I think it was the relay which I replaced). Turns out my gauge definitely runs hotter than the sensor that feeds the computer, since the gauge reads around 235 when the fan kicks on.
This leads me to believe that there is around a 10 degree difference between the gauge, and the actual temperature at the front of the block.