It still wants to overheat?

Hello TRAVIS BUTLER2,

Hey good to hear from you. I was wondering what happened to you.

Let me look over our previous conversation and information, then we will see what we can come up with.

Thank you,
Brendon

Hello TRAVIS BUTLER2,

So, since you have a multimeter, let's check and see if the Engine Coolant Temperature Sensor is getting the 5-volt reference from the PCM.

You will need to test right at the connector with it plugged in. We are going to back probe the connector with a needle or something similar.

I have added some examples of so things you could use to do this.

You are going to carefully insert a pin or a needle on the black wire with the white stripe, also referred to as a tracer. (See image)

Once the pin is in position, turn the key on.
-Black lead to batt negative
-Red on pin we just put in.

With the multimeter on Volts DC, see what you get for a reading. You should have right around 5 volts.

This sensor, according to my information, is on the top left rear of the engine. I have added a picture of it for you to make it easier to locate.

Update: I am sorry for some reason it has added images twice and won't let me remove them. Not sure why. I apologize if this causes any confusion. Please let me know if you have any issues viewing them.

Let me know what you find.

Thank you,
Brendon

Hello TRAVIS BUTLER2,

Overnight cold, ECT voltage should be within 0.5v of each other. Key on engine running, voltage should be about 1.5v-2.0v at 185-195 degrees Fahrenheit.

As coolant temperature increases, thermistor resistance signal voltage decreases.

If you take red lead and back probe the yellow wire, (ECT Signal) and black to battery ground, you are getting 1.2v with the engine cold?

Is that right?

If you have it, can you send me the part number you used to replace the ECT with? I want to take a look at it and make sure it is correct because it sounds like it is working in the opposite direction it is supposed to.

Thank you,
Brendon

Hello, TRAVIS BUTLER2,

There seems to be some confusion here on my end. The ECT is the temperature sensor. Engine Coolant Temperature Sensor.

So, I am confused as to what you actually replaced. What temperature sensor and where was it located?

Can you please clarify this for me? If you have a part number for what you have replaced, that would be extremely helpful also.

I have added part of a wiring diagram for the cooling fan circuit. It shows the ECT or Engine Coolant Temperature Sensor. It should be located on the top left (driver's side) rear of the engine.

Can you verify this is where you are testing?

Also, if the numbers you gave me are correct and you are indeed testing the right sensor AND the engine is close to operating temp, then either the sensor is bad or there is an issue with the wiring adding resistance.

This would give the wrong signal to the PCM or Powertrain Control Module will not send the signal to the relays which in turn will not turn on the fans.

Is the temperature on the dash working? Does it seem to match the engine temperature?

Let's start if you could by explaining exactly what sensor it is you replaced. So, we can clear that up.

After that I have a few other tests for ECT sensor.

Thank you,
Brendon

Hello TRAVIS, BUTLER2,

Oh, okay, I see. No problem.

Murray is a good brand. Matter of fact I probably would have used that or A/C Delco myself.

So, when it is hot our reading is way lower than it should be on the signal wire. So, the computer doesn't think the fans should be on.

Sounds like the sensor is moving in the right direction so it is reading but not the right amount.

Let's see why.

Try these 2 tests.

1) Out of Range/No Signal Test:

Red lead to black wire by back probing connector with it plugged into the ECT.

Black lead to known good ground. Battery is fine.

Set meter on Volts DC.

With the key on, engine off, voltage should be below 100mv.

Let me know what you get.

2) Then turn the key off and disconnect the ECT sensor.

Red lead to yellow wire (ECT Signal) by back probing connector.

Black lead to known good ground. Again, the battery is fine.

Set meter on Volts DC.

With the key on and the connector disconnected from the sensor you should have 5 volts on the yellow wire.

Let me know what you get for these 2 tests.

This will tell us if there is an issue with either of the 2 wires coming from the PCM.

Sometimes my instructions aren't the clearest so if you have any questions just let me know.

I will be interested to see what we find out about those 2 wires.

Thank you,
Brendon

Hey TRAVIS BUTLER2,

Hit the range switch on the meter (see image) and see if you can move the decimal point. Sounds like you might have a bad ground. Might be an issue right at the connector.

They do sell replacement connectors.

Try changing the range and see if we can get a more accurate/stable reading.

A bad ground is what is messing with that reading if that is the case.

Thank you,
Brendon

Hey TRAVIS BUTLER2,

If you find it is at the connector, I found a multi-purpose connector at O'Reilly's. Here is the part number:
STD-TX3A-Standard Ignition

If you replace it, you have to make sure your connection is one watertight and 2 has the least amount of resistance as possible so it doesn't affect the signal.

These connectors have solder and shrink with heat sealing them. They are the fastest and easiest way to make a secure connection under the hood that will last.

Soldered connections are considered the best connection as they add the least amount of resistance.

https://www.amazon.com/PCS-Solder-Seal-Wire-Connectors/dp/B077Y9QYWH/ref=asc_df_B077Y9QYWH?tag=bingshoppinga-20&linkCode=df0&hvadid=80607997944825&hvnetw=o&hvqmt=e&hvbmt=be&hvdev=c&hvlocint=&hvlocphy=&hvtargid=pla-4584207577014267&th=1

If the issue isn't at the connector, we will have to go to the PCM and unplug it and test the wire from beginning to end.

Let me know what you find.

Hope this helps.

Thank you,
Brendon

Hello TRAVIS BUTLER2,

I would check the voltages as we did before and see if we added any resistance to the circuit by making connections. More resistance will give lower voltage.

So far you have replaced all 3 relays, 2 4 prong and 1 5 prong. Replaced the connector for the ECT and replaced the ECT sensor. We tested the wiring and found the signal was lower than it should be. We also tested and found we had 5 volts from the computer which is what we want to see.

If the vehicle is warmed up and you turn the A/C on high do the fans come on?

Seems like a ground issue to me but both the wires from that sensor go directly to the PCM so there could be an issue further down in the wire or at the PCM connector.

Let me take a look at a few things and see what else I can get for information for you.

Thank you,
Brendon

Hello TRAVIS BUTLER2,

Ok. Awesome. At least part of the circuit is working. Seems like the wiring might be intact for the sensor but the reading is low on the signal wire at 1.2 volts. I mean the connector is new, sensor is new, relays are all new and work with the A/C on high. So, everything sounds like it is hooked up correctly on the fan side and the relays and fuses that power them. Plus, the signal from the PCM works for the A/C but not the ECT.

Air behind the sensor could cause it to read low. A bad head gasket could be causing the air.

There is a kit you can get it is really easy. You use a special tool with a color changing fluid, it's called block checker.

Here is a link to some:
https://www.amazon.com/Block-Tester-BT-500-Combustion-Leak/dp/B06VVBSFTF/ref=asc_df_B06VVBSFTF?tag=bingshoppinga-20&linkCode=df0&hvadid=80333123589171&hvnetw=o&hvqmt=e&hvbmt=be&hvdev=c&hvlocint=&hvlocphy=&hvtargid=pla-4583932709121118&psc=1

I use it myself all the time.

Make sure to remove a little coolant because if you get it in this tool, it will give you a false positive. If you do dump out the fluid and rinse it out and start over.

Instructions:
You are just going to fill it to the line with fluid.
Make sure your engine is cool and then remove the radiator cap.
Remove some coolant with a mighty vac fluid pump or pale pump. Something like a clean hand soap pump would work in a bind.
Then you're going to start it and let it idle.
Then place tool onto opening of coolant reservoir and squeeze included hand pump.
Depending on how bad it is you may have to squeeze it over and over until it is pretty close to operating temperature. The worse it is the quicker the fluid should turn yellow.

If it does have a bad head gasket, then the fluid will turn yellow.

I would also double check fuses really quick because we have been testing, unplugging and plugging back in things, we want to make sure we didn't pop anything. You can just use you meter for this, you should have 12 volts on each side of the fuses. A test light will work well also. Whichever one you use both will use battery for ground.

You can also remove the sensor with the engine cold. Then start the car and let it warm up. As it warms up if there is any air there it will push it out. Once all the coolant is out, you can screw the sensor back in. I will make a mess buy you should have any are behind it after that unless there is an issue with the head gasket or some other leak in the system.

I going to go over the diagrams and see if the is a splice or another ground somewhere.

Let me know how you make out with that.

Thank you,
Brendon

Hello TRAVIS BUTLER2,

I'm sorry one last thing. Was it the right or left side fan that came on when you put it the A/C on high?

Thank you,
Brendon