Just wondering which sensor would be the cooling temp sending unit for the ECM I know it's under the throttle body but is it the sensor next to the thermostat housing? Has a black and yellow wire connected Can someone confirm? and what is the purpose of it , basically how does it help you car from over heating. I have a 89 camaro rs 2.8 mpfi

 

Yes, yellow & black wires.

Has nothing to do with "help you car from over heating", except to the extent that in some cars (not sure about yours, as I know virtually nothing whatsoever about the details specific to the 6-cyl cars), the ECM is programmed to operate the fan according to its indication. Its primary function is to tell the ECM what the engine temp is, as that affects fueling and ignition timing.

 

Awesome thanks for the reply, would you also be able to help me out I have bought a new thermostat at it indicates that is opens at 195 Fahrenheit , my Haynes booklet specification for thermostat is 195 as well . My car has been overheating and i thought I would replace my thermostat to see if it was the problem but my question is would it be better to buy a thermostat with a lower temperature opening point maybe 165 Fahrenheit?

 

Not really.

It would be better to actually repair the car. After all, it worked just fine with the 195° when new; has lasted 25 years now at 195°; even though we've passed Dec 21 2012 and the world has officially ended, does it really make sense that all the sudden, 195° has changed somehow? Really?

Define "overheating". That word gets tossed around a lot; usually without any facts or details to back it up.

 

Hello I just bought my first car, it's a 1986 camaro 305 with a 4 barrel carb on it. It a base model, nothing special. It overheats and the cooling fan won't come on I don't want to jerry rig it in any way, I just want to change the sensor that could possibly be bad. I changed the fan blower relay by the brake booster and I also changed a sensor on the passenger head near the oil dipstick it is connected to a green wire and it still won't come on, the fan works if I turn the A/C on, I let it heat up to about 220 then I kick it on but it won't come on automatically if I jump out the A/C fan relay it will kick on. I see another sensor on the drivers side head I'm not sure what it's for or what it does, I'm stuck and don't know what else to changed. Please help me I'm open to any suggestions. Thank you

 

I'm no expert but the the "sensor" you replaced with the green wire is the sending unit to the gauge, try changing the coolant temp sensor next to the thermostat housing (yellow blk wire) if you haven't done so already. They look identical... If not I would try coolant fan switch if yours has one I'm not sure if it does, you would have to look into that.

 

Do your fans turn on when the car gets up to temp?

Is your air dam intact?

 

@JamesG1986:
Not sure about your specific engine, but on the LB9 engine there's a sensor on the driver's side head which delivers values for your dash gauge, a pressure switch in the passenger's side head for secondary fan activation under high pressure conditions, which also means the use of the A/C, and a third sensor up front somewhere below the throttle body, which delivers values to your ECM and allows the primary fan to start when a certain temperature is reached (230°F/110°C IIRC).