bigbovine

OK, I got a 96 Cherokee recently. Temp sender at firewall on block was broken , so went to parts store and got a new one and installed it.
Temp gauge when vehicle is warm shows around 230 to 245 degrees. I was told to ohm the sender to check it. I did and while in that range of temperature I gave above, it read between 135 and 145 ohms at sender.
The electric fan cycles on and off with the rise and lower of the ohms, so I don't think I am running 240 degrees (It runs off a different sender).
I took a Temp Gun that I use in heat and air work (I do not trust it to give me actual temperatures, but have tested it and found it gives accurate differances no matter what it says the temperature is, does that make sense?) and the upper heater hose read between 170 and 185 while the block in the same area would read 190 to 210 (So I am for certain the pump is working).

I then pulled the gauge cluster to check the wires at that end to see if I am getting good ground there. That is where I got lost. I see the 3 screws in the back labeled "grd", "ign", "tsu" (I believe that is right). I read somewhere to take a wire and ground at the gauge but do not want to do something that messes the rest orf the cluster up.

Here is where I got my information
http://www.autometer.com/tech_faq_an...x?sid=1&qid=57
http://www.marshallinstruments.com/f...tail.cfm?id=33
http://www.marshallinstruments.com/products/9204.cfm

Am I right in saying that I am running at normal temps based on ohms at sending unit and something is wrong at the gauge?
Also, if I want to run a "better" ground to the gauge on the cluster to check it (Remember that it is a plastic sheet with copper running around and labeled screws holding gauges with one pigtail hooked in, sorry I understand you guys may know this but wanted to make sure), would I run that wire to the screw labeled GRN (It runs to several so I would assume it is ground)?

bigbovine

A side note, While under the dash I noticed a small object around the size of a C battery with about three wires coming from it. The reason I noticed it was because it was really, really hot. I will try to get a pic next time I am in there, but does anyone have an idea what it is??

Radi

IIRC the sending unit should run closer to 700 ohms at operating temp. I used to have a chart for that, lost when my last notebook died else I'd post it.
Lower resistance = higher temp indication.
Where'd you get the new sender? Some of the aftermarket stuff isn't even close.

No idea what the c-cell shaped thing is, but nothing under the dash should run hot. Get a pic!

cruiser54

100* 1365 ohms
220* 93.5 ohms
260* 55.1 ohms

bigbovine

Ok here is a pic of the object under dash.

bigbovine

Ohm info, please be sure and read the information I read to see what I am saying. By that information (If it is correct) my sender is operating correctly right?
Also, I put the leads on the temp sensor (Two wires) at the front that controls the elec fan. It showed 700 when motor was heated up.