Temp guage not reading right

[Iron Weasel]

Did you replace the one wire sensor that surf told you to replace or the two wire sensor that I suggested you replace?

 

[tjsxplodr]

I have yet to replace both sensors. I did the paperclip method of testing the ONE wired sensor, and the temp gauge went right up to the H, like its supposed to.

I am unsure how to use my multimeter, its got all kinds of settings for the resistance. 20K 200, 2000, 200k, 2000k. I've got my red wire plugged into the VmA(upside down u) and the black wire set to com. I want to test both sensors, but not sure what setting to put my meter on.

 

[Iron Weasel]

Ω = Latin Letter "Omega". This is the symbol used to identify resistance measured in Ohms.
K = Metric prefix "Kilo". It means 1000, so for example, 1kg would mean one thousand kilograms.

On a DMM (Digital Multimeter), the different settings are used when you need to measure varying levels of resistance. So an example scale would look like this:

20 = 20 ohms.
200 = 200 ohms.
2k = 2,000 ohms.
20k = 20,000 ohms.
200k = 200,000 ohms.
2000k = 2,000,000 ohms.

If you set it too high, like 200k, then you likely wouldn't be able to see the resistance on the display. If you set it too low, then it's likely that the meter will just error out. Try starting it on the lowest setting, 200Ω or whichever you have, and then go up if it gives you an error.

 

[tjsxplodr]

I have all of those, so which is the least, the 20 ohms?

BTW, no coolant flow at all with rad cap off, temp in rad was 130 degrees. Temp at top hose 145. Bottom hose I didn't read cuz it was way cooler than top hose.

 

[Iron Weasel]

20 is less than 20 thousand, right?

When the thermostat opens, the upper radiator hose should be considerably warmer than the lower hose since the hot coolant is coming out of the engine at the top and then goes back into the engine via the lower hose.

 

[tjsxplodr]

Ok yes 20 is less hehe. But the coolant wasn't moving at all.....

 

[Iron Weasel]

If there's no coolant flow and the temperature of both hoses is the same, then it's highly likely you have a bad water pump.

 

[tjsxplodr]

Well, I didn't measure the temp of the lower hose, I measured the top hose at 145 and it was HOT. The bottom hose wasn't as hot, but still warm.
The coolant didn't seem to be moving at all when I had the rad cap off, I had the X running for like 10 minutes...and it wasn't even completely cooled off from when I got home.

 

[Iron Weasel]

You might not be able to see the coolant moving, but if the lower hose is cooler than the upper, then the pump and thermostat are probably good since the coolant is moving through the engine and radiator like it's supposed to.

 

[tjsxplodr]

Ok, so how do I check the sensors then? Do I turn the key on and test them that way?

 

[Iron Weasel]

Disconnect the coolant sensor and measure resistance between sensor signal circuit and SIG RTN circuit at the temperature sensor. It's best if you do it with the engine is at operating temperature, so start off with the 20K setting on your meter. Compare the values you get to the values on the chart.

Note: Engine coolant temperature must be greater than 10°C (50°F) to pass the KOEO Self-Test and greater than 82°C (180°F) to pass the KOER Self-Test. To accomplish this, the engine should be at normal operating temperature.

Voltage values were calculated for VREF=5.0 volts. These values may vary 16 percent due to sensor and VREF variations.

This is for the 2-wire sensor. I couldn't find any electricl specifications for the single wire sensor so it's assumed that the 1-wire sensor is cheap enough to just throw another one on if it's bad. And you want the Key On, Engine Off when you do this.

 

[tjsxplodr]

It turns out the temp sender was bad. $9 fix Thanks guys!