coolant temp gauge issue

7M4EVR

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Oct 8, 2012
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3p141592654;1985666 said:
Read the resistance on the ECU sender (two prong one) beside the gauge sender and see if it is reading hot too.

http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?Section=FI&P=113

3P- I see where you are going and it should tell me my problem. Do you know of a good method I can use to monitor the coolant temp of the car? Such as a thermometer in the overflow tank or something (would this give an accurate temp you think). The pot of water won't help me in this case. The ECU sender was brand new about 2 weeks ago, so hopefully this should tell me if its my gauge sender or something else. Another quick little insert...I tried using the sensor for the auxillary fan as well and temp does the same thing. I think signs are pointing to the car actually being hot. Does this sound like a bad T-stat?

@supraguy- I thought about that, but the car never cools off at all once it gets to H it stays there as long as i let the car run. Also, I can feel/ hear the coolant coming through the upper radiatior hose and it feels like its flowing smoothly. However, it's easy enough to try so i will bleed/flush the system when i get a chance.
 
Oct 11, 2005
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Thousand Oaks, CA
The fan sensors are just switches, either on or off. Hooking them to your gauge is not helpful.

Just measure the resistance across the two prongs of the Ecu sensor and compare to the graph. You will know right away if it is hot.
Jon
 

7M4EVR

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Oct 8, 2012
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Im still trying to get to this....my afm finally completely crapped out on me too (shit always comes in bunches with this car)...then I bought one off ebay and its even worse. As soon as I get the car running again ill be back at this. However I am going to get a digital water temp gauge anyhow...does anyone know of any that just happen to work with the stock sender? Either that or know the thread size of the stock sender off hand?
 

7M4EVR

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Oct 8, 2012
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fah, fah away
Cant leave threads unresolved...ended up just replacing the thermostat, coolant temp sender, ecu coolant sensor, radiator cap, and flushed and refilled the coolant. All better! I guess when everything else fails just replace it all. 99% sure it was the thermostat stuck closed and not letting coolant flow. Good thing I didnt risk driving it thinking it was a bad sender