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Coolant Gauge Not Working / Aux Electric Fan Only Works When Coolant Sensor Unplugged
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go hereXJ (84-01)
All OEM related XJ specific tech. Examples, no start, general maintenance or anything that's stock.
Coolant Gauge Not Working / Aux Electric Fan Only Works When Coolant Sensor Unplugged
Two Primary Issues: 2000 XJ Sport with 4.0L Inline 6 1) Coolant Gauge is Not Working
a) Car is turned off it goes all the way to left/bottom of gauge reading 100
b) Car is running it stays right in the middle at 210 regardless of actual temperature (coolant sensor plugged-in). Never moves from there
c) Car is running AND Coolant Sensor is Unplugged goes all the way to left/bottom of gauge reading 100
d) I've read threads talking about difference between Sensor & Sender Unit. From my understanding there is no separate Sender Unit on 97-01 XJ's. I know for sure that there is nothing at rear/back of block that could be a separate Sender unit as this is a 2000 XJ.
e) Have read threads talking about how temp sensor needs to be "white" for "gauge" & how "black" is setup for "light" only. Think this might apply to pre-97 XJ's only with separate sensor & sending units, but not sure.
f) Darn thing moves, but I've never seen it go above the 210. Would be nice to know if my car is starting to overheat before it completely shuts off when driving down highway!
2) Auxiliary Electric Fan Only Turns on When Coolant Sensor Unplugged
a) Fan works. Was replaced recently. Have double-checked by straight wiring.
b) Fan works when coolant temp sensor Unplugged and A/C is on.
c) Fan does not come on when coolant temp sensor Is plugged in. Have tried with A/C on and off as well as when at operating temperature.
d) Replaced the temp sensor about 6mos ago with MPI 2-9361 from O'Riley. At that time I replaced water-pump, thermostat (195deg) and did complete flush. Prior to replacing that temp sensor the aux fan did come on when it should have, but temp gauge in cabin has never worked properly since I've owned car. Unfortunately I threw away the old temp sensor as I thought it was bad. Maybe I should track down OEM one? Have seen threads listing #56027012
e) Relay is fine - I've 3x checked.
Get an IR temp gun and shoot the thermostat housing and compare to your gauge. Unhooking the sensor causes the e-fan to activate it's a failsafe. AC on or off on a 2000 makes no difference. On 2000-2001 they changed the way the e-fan activates. AC use has no bearing on fan running only coolant temperature. E-Fan should engage when coolant temps reach something like 220ish degrees then off again when it gets to a certain lower temperature. I"d have to look in the FSM for the exact numbers.
Pick up a plug in bluetooth OBD reader and get an app called Torque for your phone. Then you can see exactly what the computer sees for temperature data.
You wouldn't be the first guy/gal to come in here worried that their e-fan wasn't working on their 00-01 when in fact it's working just fine.
Does it go to "210" as soon as you turn the key to on?
Rock auto shows a MOPAR sensor still in stock for less than 50 dollars.
Two Primary Issues: 2000 XJ Sport with 4.0L Inline 6 1) Coolant Gauge is Not Working
a) Car is turned off it goes all the way to left/bottom of gauge reading 100
b) Car is running it stays right in the middle at 210 regardless of actual temperature (coolant sensor plugged-in). Never moves from there
c) Car is running AND Coolant Sensor is Unplugged goes all the way to left/bottom of gauge reading 100
d) I've read threads talking about difference between Sensor & Sender Unit. From my understanding there is no separate Sender Unit on 97-01 XJ's. I know for sure that there is nothing at rear/back of block that could be a separate Sender unit as this is a 2000 XJ.
e) Have read threads talking about how temp sensor needs to be "white" for "gauge" & how "black" is setup for "light" only. Think this might apply to pre-97 XJ's only with separate sensor & sending units, but not sure.
f) Darn thing moves, but I've never seen it go above the 210. Would be nice to know if my car is starting to overheat before it completely shuts off when driving down highway!
2) Auxiliary Electric Fan Only Turns on When Coolant Sensor Unplugged
a) Fan works. Was replaced recently. Have double-checked by straight wiring.
b) Fan works when coolant temp sensor Unplugged and A/C is on.
c) Fan does not come on when coolant temp sensor Is plugged in. Have tried with A/C on and off as well as when at operating temperature.
d) Replaced the temp sensor about 6mos ago with MPI 2-9361 from O'Riley. At that time I replaced water-pump, thermostat (195deg) and did complete flush. Prior to replacing that temp sensor the aux fan did come on when it should have, but temp gauge in cabin has never worked properly since I've owned car. Unfortunately I threw away the old temp sensor as I thought it was bad. Maybe I should track down OEM one? Have seen threads listing #56027012
e) Relay is fine - I've 3x checked.
Any help greatly appreciated!
What's the problem? Everything you described is how it's supposed to work. If you want your gauge to go above 210 and overheat your engine, just drain half of your antifreeze out and run the engine. Then the gauge will spike to 260 and you will crack the weak 2000-01 head.
Last edited by TheBoogieman; 05-25-2020 at 04:19 PM.
What's the problem? Everything you described is how it's supposed to work. If you want your gauge to go above 210 and overheat your engine, just drain half of your antifreeze out and run the engine. Then the gauge will spike to 260 and you will crack the weak 2000-01 head.
True...However if you want to see if the gauge does go past 210 come on down to Georgia in 2-3 months and let it idle with hood closed...
True...However if you want to see if the gauge does go past 210 come on down to Georgia in 2-3 months and let it idle with hood closed...
If your cooling system is working properly it will stay at 210. I know people wheeling in the Arizona desert for many hours with temps well over 110. Their Jeeps still run 210.
If your cooling system is working properly it will stay at 210. I know people wheeling in the Arizona desert for many hours with temps well over 110. Their Jeeps still run 210.
If there is not enough air moving it will run hot. Noticed I said idle and with hood closed in July/August in Georgia...trust me it eventually will run hot.
Guess I should've clarified, but enjoyed some of the entertaining responses...
The gauge would immediately go to 210 upon startup and stay there. Absolutely no movement either down or up regardless of running temperature. XJ overheated a couple times with the idiot-proof auto-shutdown, gauge was always sitting at 210. One shutdown was on highway, not fun. Had a friend run an OBD - got these codes:
P0118 - Engine Coolant Temperature Circuit - High Input
P1491 - Radiator fan relay control circuit
P0705 - related to transmission control module
P1899 - Park/Neutral switch stuck in park or gear
Looks like 2nd two indicate another potential issue, more fun for me.
Brought it back home and triple-checked all the connections. Started it up and the gauge was working! With A/C on after warming up, gauge slowly moved up to roughly 220 mark and fan came on - thx downs! Makes sense with P1491 code, but wonder if the P0118 code might indicate something else I should look into? Appreciate any intel
Could be a poorly calibrated sensor. Use this chart and your multimeter to check it out at various temps. If its out of whack i know of no way to adjust it just replace.
If there is not enough air moving it will run hot. Noticed I said idle and with hood closed in July/August in Georgia...trust me it eventually will run hot.
You need a good chemical flush of your cooling system.
You need a good chemical flush of your cooling system.
So if coolant temps stays at 210 all the time why do we have a electric fan on the 2000 xj and why does it come on around 218? he was wanting to know if his gauge will go past 210 and my scenario should cause that to happen. I did not sate overheating guess I should of worded it better and said said hotter...my bad!
Took out the temp sensor that I bought at O'Riley (thought it'd just be good to replace at same time as water-pump for some reason...) and put the old one back in. Now aux fan and coolant temp gauge seem to be working just fine. I've cross-checked coolant temp on OBD which does line up with gauge. Think the sensor from O'Riley was crap.
OBD Readings: Previously was just getting P0118 (coolant high), which still coming up but also getting P0117 (coolant low) now? P1491 - Radiator fan relay control circuit code is now gone
XJ is still stalling out. tends to do so at temp around 220. After letting it sit to cool for 20-30min starts up again just fine.
Realized vapor lock may be the problem or part of it after hitting presta valve on fuel rail after it stalled. Straight vapor
Installed DEI Fuel rail kit with fuel rail wrap, heat shield, etc. - may have helped some...
Still stalling out around 220, typically on hot 90+degree day. Should this be happening? Anything else I should be looking at? Are there any good aftermarket aux fans that are higher-powered or other mods I should be considering?
05-25-2020, 12:48 PM
Coolant Gauge Not Working / Aux Electric Fan Only Works When Coolant Sensor Unplugged
