Water temp. Sensors

Sonyps307 · 03-03-2011, 03:20 AM

What are the names of the three water temp. Sensors that are right before the thermostat. I want to replace them but the auto store has no idea what I'm talking about. Then they try to sell me a sensor that doesn't go on my car.

cre · 03-03-2011, 04:23 AM

You're probably only going to be able to get from a dealership or a Toyota parts dealer. Have you tested them? No need to blindly replace them.

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Sonyps307 · 03-03-2011, 05:14 AM

I have not tested them. I have a n/a I don't have the fan switch or the a/c sensor I have the other two and one more that goes in the top of the housing by the bvsv

Bru · 12-12-2012, 03:22 AM

does anyone know how to test the functionality of the AC coolant temperature sensor and the radiator cooling fan switch? Using a volt ohm meter, should there be continuity when its at operating temperature or before starting the engine? Do the sensors connect when it gets a higher than average temperature or is it a resistance sensor that can be measured?

cre · 12-12-2012, 04:05 PM

I don't recall ever needing anything other than a pot of boiling water and a multimeter to test any of the car's temp sensors. The details about testing the sensors for the A/C system are covered in the TSRM.

http://www.cygnusx1.net/Supra/Librar....aspx?S=AC&P=1

Bru · 12-13-2012, 02:46 AM

Its on Page AC-33. They are called They are called water temperature switch No.2 and No.3. Found on the 7M-GTE E/G model only. The diagrams are a bit tricky to interpret.
It looks like the N0.3 switch causes the radiator fan to come on when the coolant gets to
100 C then shut off at 95 C. So there would be no resistance at the sensor until it gets to
100 C. The diagram for the No.2 A/C coolant switch is less clear.

http://www.cygnusx1.net/Supra/Librar...aspx?S=AC&P=33

cre · 12-19-2012, 04:18 AM

No 2 is open until 112?C then it closes until temps drop back down to 107?. The illustration is confusing because it's mirrored from the next one leading you to expect continuity UNTIL 112?...

Bru · 12-20-2012, 12:24 AM

Ok, I have them backwards. Its clear the the number 3 closes at 100 and opens at 95C.
Probably to run a fan. Its the number 2 switch diagram that is not clear to me.

cre · 12-20-2012, 03:07 AM

Refer to the TEWD and the TEWD's tech notes. It'll probably clear it up for
you.

http://www.cygnusx1.net/Supra/Librar...x?S=Main&P=140

03-03-2011, 03:20 AM	#1
Sonyps307 Lexus & 550's Join Date: May 2010 Location: Baltimore Posts: 526	Water temp. Sensors What are the names of the three water temp. Sensors that are right before the thermostat. I want to replace them but the auto store has no idea what I'm talking about. Then they try to sell me a sensor that doesn't go on my car.

03-03-2011, 04:23 AM	#2
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	You're probably only going to be able to get from a dealership or a Toyota parts dealer. Have you tested them? No need to blindly replace them. __________________ If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum. If you're so inclined I'm always more than happy to accept tips via PayPal. Tip Jar --->

12-12-2012, 04:05 PM	#5
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	I don't recall ever needing anything other than a pot of boiling water and a multimeter to test any of the car's temp sensors. The details about testing the sensors for the A/C system are covered in the TSRM. http://www.cygnusx1.net/Supra/Librar....aspx?S=AC&P=1 __________________ If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum. If you're so inclined I'm always more than happy to accept tips via PayPal. Tip Jar --->

12-19-2012, 04:18 AM	#7
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	No 2 is open until 112?C then it closes until temps drop back down to 107?. The illustration is confusing because it's mirrored from the next one leading you to expect continuity UNTIL 112?... __________________ If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum. If you're so inclined I'm always more than happy to accept tips via PayPal. Tip Jar --->

12-20-2012, 03:07 AM	#9
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	Refer to the TEWD and the TEWD's tech notes. It'll probably clear it up for you. http://www.cygnusx1.net/Supra/Librar...x?S=Main&P=140 __________________ If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum. If you're so inclined I'm always more than happy to accept tips via PayPal. Tip Jar --->

03-03-2011, 05:14 AM	#3
Sonyps307 Lexus & 550's Join Date: May 2010 Location: Baltimore Posts: 526	I have not tested them. I have a n/a I don't have the fan switch or the a/c sensor I have the other two and one more that goes in the top of the housing by the bvsv

12-12-2012, 03:22 AM	#4
Bru Bone Stock w Upgrades ;-) Join Date: Apr 2010 Location: Tampa Bay Posts: 210	does anyone know how to test the functionality of the AC coolant temperature sensor and the radiator cooling fan switch? Using a volt ohm meter, should there be continuity when its at operating temperature or before starting the engine? Do the sensors connect when it gets a higher than average temperature or is it a resistance sensor that can be measured?

12-13-2012, 02:46 AM	#6
Bru Bone Stock w Upgrades ;-) Join Date: Apr 2010 Location: Tampa Bay Posts: 210	Its on Page AC-33. They are called They are called water temperature switch No.2 and No.3. Found on the 7M-GTE E/G model only. The diagrams are a bit tricky to interpret. It looks like the N0.3 switch causes the radiator fan to come on when the coolant gets to 100 C then shut off at 95 C. So there would be no resistance at the sensor until it gets to 100 C. The diagram for the No.2 A/C coolant switch is less clear. http://www.cygnusx1.net/Supra/Librar...aspx?S=AC&P=33

12-20-2012, 12:24 AM	#8
Bru Bone Stock w Upgrades ;-) Join Date: Apr 2010 Location: Tampa Bay Posts: 210	Ok, I have them backwards. Its clear the the number 3 closes at 100 and opens at 95C. Probably to run a fan. Its the number 2 switch diagram that is not clear to me.

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