DaddyCat

My xj has stayed steady at one mark to the left of 210 (when fully warm). Anyone know for sure what numbers the lines equal?

I divided 110/4 (210-100=110, another four lines from 100 to 210) and get 27.5 degrees for each line which would make the mark to the left of 210 182.5 degrees.

However to the right of 210 we have another 4 lines to get to 260.
260-210= 50, 50/4= 12.5 every line to the right of 210 = 12.5?

Is this right, are the lines magically a different value on opposite sides of 210? Are the lines progressive and not linear?

djb383

Are u running a 195 t-stat? Something like this.

DaddyCat

I just bought a 195 t-stat today, not yet installed, I'm not sure what's in there now. My little drawing looks like yours..lol Does that seem possible the values are as you (and I) wrote them?
I was expecting the values to be linear.

djb383

Our XJ has lights....we run a ScanGauge for accurate temp readings.

DaddyCat

Thanks, you have the ScanGaugeII? very interesting tool.

I still would like to understand why the graduation values on my temp gauge are different either side of 210 degrees. Maybe the head unit has different resistance values below and above 210 degrees.

djb383

The 3 GM p/u's I've owned had the same gauge display....100, 210, 260. Maybe someone with a ScanGauge and factory gauge will chime in. We've momentarily seen 230 on the ScanGauge, triple digit ambient, stop-n-go traffic, using a/c but even at 230, the factory idiot light never flickered.

DaddyCat

Dang, I thought it was such an interesting mystery. Nobody knows?
Progressive, double linear, or some kind of curved resistance values?

djb383

Which one of those three would it be if it just indicated "C" and "H" like most factory gauges? LOL

DaddyCat

http://www.ectinschools.org/page.php?ps=2&p=42

Depending on how they manipulate the thermistor signal the output could be a curve or a somewhat straight line. Still doesn't help me understand how the line values above 210 seem to be ~ 1/2 the line values below 210.
Makes my head hurt.

djb383

Your not saying that the factory gauge(s) is/are manipulated......are u? (I've said that all along) Install an aftermarket temp gauge, your head will stop hurting.

DaddyCat

LOLOL I don't KNOW if the output is manipulated, it may be. What gives me the headache is not knowing how something works. It's not really that I'm worried if my gauge is accurate, I belive it's "close enough". And as much as you may like your ScanGauge it is only as accurate as the CTS installed in your engine, right?

Again, I appreciate you trying to help me but it's the mysterious change in values either side of 210 that I want to understand.

djb383

I don't know how the factory gauge works......that progressive, double linear, curved resistance stuff is way over my head. I do know that most factory temp gauges basically just sit in the middle and stay there as long as normal operating temp (factory set parameters) are not exceeded. Depending on ambient temp, driving conditions, engine load, etc., etc., those "normal" temp parameters can easily have a +/-40 degree swing from low to high. I like seeing that +/-40 degree swing displayed on a good accurate aftermarket gauge (digital or analog) rather than just seeing a needle sitting in the middle of the gauge, year round, under any driving conditions. I'm just weird that way and think a temp gauge with 3 numbers or a C and H are worthless as teats on a bore hog. Show me the numbers...the real numbers, not the horseshoes or hand grenades. LOL