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Temperature sensor HELP!!!

 
makavelirhyme
I love my Chevy Chevette!
Posts: 3
Joined: 09/10
Posted: 09/18/10 07:06 PM

I can not find where my Temperature coolant sending unit is in my 1991 corvette. Been searching for hours and still cant find it!!! I'm not talking about the temperature sensor. The SENDING UNIT!!!Someone please help  

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waynep7122
I mow my lawn and find Chevys
Posts: 1114
Joined: 08/09
Posted: 09/18/10 08:59 PM

the coolant temp sensor for the computer on a 91... is on the front of the intake... below the thermostat housing aiming forward...  usually with a yellow and black twisted pair of wires to it...

the engine temp sensor for the gauge is in the left cylinder head between the number 1 and 3 spark plugs...

the cooling fan override temp switch is in the right cylinder head... between the 6 and 8th spark plug... if used... if you car has two fans... one is computer operated... the other is operated by this sensor grounding when the temp exceeds the normal temp... there will also be 2 cooling fan relays... if your car has 2 fans...


there is an AIR CHARGE temp sensor on the bottom of the upper plenum.. its really hard to get to but usually connected with a short extension pigtail... sometimes not...

here is a link to the component locator..

http://repairguide.autozone.com/znetrgs/repair_guide_content/en_us/images/0900c152/80/08/fc/a5/large/0900c1528008fca5.gif  

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makavelirhyme
I love my Chevy Chevette!
Posts: 3
Joined: 09/10
Posted: 09/20/10 12:45 AM

The temperature coolant sending unit looks like this:50419. So would that be the one on the passenger side of the engine?  

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waynep7122
I mow my lawn and find Chevys
Posts: 1114
Joined: 08/09
Posted: 09/20/10 10:21 AM

that one is for the gauge.... goes in the left head..  between spark plugs one and three... the  first and second plug...   1 x 3___5   7    the picture you posted is the temp sender...    it has a single terminal..   variable resistance to the shell of the sending unit...   when this changes resistance.. it  changes the display on the instrument cluster...

there are slight variations in names that not all parts men understand...

the one with this connector goes in the front of the motor.... it is the coolant temp sensor az part number su109.......     this sensor has variable resistance... and is isolated from the shell..  the ecm sends 5.0 volts down one wire.. the resistor reduces the voltage to the other wire.. the computer looks at that voltage and computes it into temp to set the fuel mixture...

Ctsinside

Su109

this is the proper pig tail for it... these pigtails do go bad and some coolant temp sensors come as a kit with it for much cheeper than the 2 pieces individually..   part number 254...

i might explain farther...  this fan switch circuit is open... until the coolant temp reaches 230F.. then it closes..

254]

254Sideview


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

this one goes in the right cylinder head... between the  6 and 8 spark plugs   duralast s500 at autozone...

Radiatorfanswtichtopview

Radiatorfranswitch S500sideview

this is the proper connector for the fan switch in the right head..
duralast  231 at autozone...
Radiatorcoolingfanconnector231  

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vetteoz
V-6 Camaros rule!
Posts: 58
Joined: 07/08
Posted: 11/15/10 02:55 PM

the cooling fan override temp switch is in the right cylinder head..... if you car has two fans... one is computer operated... the other is operated by this sensor

All '90+ cars have two fans mounted behind radiator, both fans are only controlled by the computer; there is no switch in drv side head.
Pri fan runs with engine , Sec fan runs with A/c or if engine goes over a certain temp

Mech fan switch in head was only fitted on '86-'89 cars with optional ( B4P ) aux fan in front of radiator
Aux fan also part of Z51 package in those years  

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