Coolant Temp. Sender (gauge) testing?

[kazam]

Greetings,

 

I have a 2.5L I-4 engine (1987).

 

The coolant temperature gauge does go through the register while powering on; then when running the indication stays at 100 deg.

 

I am away from my set of manuals for this Jeep.  It's been a while since I tested one of these.

 

Maybe someone can inform me on how to test the sender/ sensor (the one up top on the engine, near the firewall, for the gauge) before I spend $25 or so on a replacement.

 

I have a multimeter and boiled water available.

 

 

I am aware that the sender is a thermo-sensitive resistor.

 

I am not clear on what resistance values are standard for this part.

 

I am thinking, the resistance-value lowers, as the temperature rises.

 

I'll check it this next Monday.

 

I would appreciate a heads-up in case I have overlooked something Important.

 

Thanks very much.

[Eagle]

For the 1987, the range is 0 to 88 ohms. I believe 0 is cold and 88 is hot. I don't remember if the FSM provides values for points in between.

 

Out of curiosity, how are you reading 100 degrees on the gauge? The scale is not linear, and I don't think there's an enumerated point for 100 degrees.

[cruiser54]

[kazam]

Greetings,

 

That is really helpful.

 

Thanks Very Much.

[Eagle]

That is good infor. I'd like to know where it's from, because my 1988 factory electrical manual doesn't have those charts in it.

 

All these years I've thought the temperature gauge ran on the same 0 - 88 ohm range that the fuel gauge and oil pressure use. Live and learn!

[cruiser54]

Eagle, photos from my FSM.

[HOrnbrod]

All 2.5L & 4.0L MJ's use a 1365Ω temp sender for the gauge. Don't know about the 2.8L though, don't care either........ :yes: