hbracing13

So I recently replaced my motor I'm my 92 xj that had the 7120 head with a motor out of a 97 with a 0630 head. Well doing so I completely forgot about it not having the sensor drilled in the back, so I extended the wire to the thermostat housing as the renix do with a newer head. I have noticed that I the factory temp gauge stays at almost the red line but doesnt cross over with still no e fan engagement. I have watch it carefully with my IR thermometer and it does not reach even that close on the the thermostat housing, other then having a bad ECT sensor for the pcm or the gauge.
I'm looking closer to the gauge being NFG. I haven't tested the resistance to see if I'm actually reading hotter then I should yet plan on tomorrow. And it only had water it for now. I've done it in the past with no problems this is the first one.
What else am I missing so that the e fan kicks on and the temp gauge actually reads correct and not spiking to the hot side?

alpine.adrenaline

It sounds like you have the older "idiot light" style sending unit, but if it's a '92 I'm not so sure... If that were the case its either an on/off thermal switch to illuminate a caution light on your dash. A guage requires the variable resistance-type temperature sender. If I remember correctly on Renix-era Jeeps the gauge/light temp sensor is in the back of the head, and the sensor the PCM uses for emission control is in the thermostat housing.

cruiser54

92 should have a temp SENSOR in the housing for the fan/PCM, and a temp SENDER at the back of the head.

alpine.adrenaline

Bingo- thanks for clarifying that nomenclature. But will a '97 sensor work with a '92 PCM?

cruiser54

97 has a combination Sender/Sensor in the thermostat housing only.............

hbracing13

You know what I may have not changed sensors when I did the swap. I used the 97 housing as it was not corroded as bad as the 92 one but didnt swap sensors out. I didnt think it would of made a difference.
I did swap the sender out for the gauge as I swapped clusters.
I guess I should be asking what other problems will I have having the gauge sender moved on the thermostat housing?

hbracing13

This is what i did




Since i didnt have this .

cruiser54

You might be okay except for using the wrong SENSOR.

hbracing13

Sensor was correct the 97 had a different kind of plug. I tested the sensor itself it's reading like it should. But the gauge still climbs up past 210. Oh I also have the zj clutch fan being that I know it helps out but it doesn't seen to do anything then before. I'm going to replace that sensor for piece of mind, and try so other things. If this doesn't work what are going to be my other options?