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Coolant temperature sensor

Tiny
CHRISJASON2000
  • MEMBER
  • 1994 CHEVROLET S-10
  • 4.3L
  • V6
  • 4WD
  • AUTOMATIC
  • 170,000 MILES
Hi, so when I bought the truck I was unaware of a heating issue. After my intake manifold gasket blew I replaced it. I then started noticing as I was putting the engine back together I was having an overheating problem as my gauge has never worked and the cord connected to my temperature sensor was gone. My truck thinks it’s always cold and doesn’t circulate coolant. I can’t find where the sensor was connected to on the other side of the sensor connector. I guess it goes to my PCM somewhere but knowing that doesn’t help me I need to figure out how to reconnect my sensor wire so I can plug into it. I know they have a temperature control switch too which is separate from that but I can’t figure out what to do. I just need to know how to reconnect everything so my engine knows to circulate coolant and so I can see my gauge working. Please help, been banging my head off this truck trying to figure out where the wire connects to. Also a PCM pin out chart would be helpful so I know which circuit to attach to and the PIN number for that circuit.
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Thursday, June 6th, 2019 AT 12:29 AM

10 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good morning,

The sensor just tells the dashboard the temperature of the coolant. It has no control on circulation of the coolant. That comes from the water pump and the thermostat opening at the correct time.

It is located on top of the motor by the thermostat.

Roy
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Thursday, June 6th, 2019 AT 3:29 AM
Tiny
CHRISJASON2000
  • MEMBER
  • 10 POSTS
Okay, so my thermostat is the only thing that controls coolant flow or what would be making it think it’s cold?
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Thursday, June 6th, 2019 AT 3:35 AM
Tiny
CHRISJASON2000
  • MEMBER
  • 10 POSTS
And I’m aware that’s where it is. I’m just wondering where it connects to in the PCM. I need the pin out chart and which circuit it connects to and what PIN number that circuit is. Because I can’t find any wire where it was connected to previously so I’m going to start from the computer and work my way towards the engine.
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Thursday, June 6th, 2019 AT 3:37 AM
Tiny
CHRISJASON2000
  • MEMBER
  • 10 POSTS
So how do I tell if my water pumps out or if it’s my thermostat?
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Thursday, June 6th, 2019 AT 3:37 AM
Tiny
CHRISJASON2000
  • MEMBER
  • 10 POSTS
And I also think that picture is wrong because my sensor is on the left side of the engine. If you were sitting in the vehicle and between my third and fifth spark plug.
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Thursday, June 6th, 2019 AT 3:39 AM
Tiny
CHRISJASON2000
  • MEMBER
  • 10 POSTS
And do I have a coolant temperature switch and a cool ant temperature sensor or is there just one? Because I’m pretty sure my sensor not being connected would make my coolant not flow because it’s telling the computer it’s cold.
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Thursday, June 6th, 2019 AT 3:42 AM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Again, the sensor has no connection to flow of coolant. It does not tell the computer anything but the temperature.

The location is a generic view.

I would replace the thermostat anyway as that may be the issue.

https://www.2carpros.com/articles/replace-thermostat

Roy
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Thursday, June 6th, 2019 AT 3:58 AM
Tiny
CHRISJASON2000
  • MEMBER
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That is not my ECM schematics at all.
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Thursday, June 6th, 2019 AT 4:08 AM
Tiny
CHRISJASON2000
  • MEMBER
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Here’s a picture of my computer connectors.
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Thursday, June 6th, 2019 AT 4:11 AM
Tiny
ASEMASTER6371
  • MECHANIC
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Picture did not come through.

Roy
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Thursday, June 6th, 2019 AT 6:31 AM

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