2006 Buick Lacrosse 3.8 Engine Coolant temp sensor

[sliverbuick]

I recently got a code that reads Engine Coolant Temperature Circuit High Input so i replaced the sensor and plugged it back in and it still has the code. So I made sure the wiring was good and there was no damage at all to the connector or the wiring and i cleaned both the connector and plug connection with cleaner so it has good contact. The car is still throwing the code and my ac fans kick on as soon as i start the car and stay on till i turn the car off. I’ve checked everything and looked online and just can’t seem to figure out what the issue is.

 

[MelsRegal]

What is the code?

 

[sliverbuick]

What is the code?

P0118 which it said coolant temperature sensor so i replaced it and the car still throws the code even after i clear it and the ac fans stay on the whole time till the car turns off

 

[MelsRegal]

P0118 which it said coolant temperature sensor so i replaced it and the car still throws the code even after i clear it and the ac fans stay on the whole time till the car turns off

What brand and part number did you install?

 

[sliverbuick]

What is the code?

P0118 which it said coolant temperature sensor so i replaced it and the car still throws the code even after i clear it and the ac fans stay on the whole time till the car runes

What brand and part number did you install?

I used duralast and the part number is SU102

 

[MelsRegal]

P0118 which it said coolant temperature sensor so i replaced it and the car still throws the code even after i clear it and the ac fans stay on the whole time till the car runes

I used duralast and the part number is SU102

Need a live data scan tool to see what the PCM is reading.

 

[sliverbuick]

Need a live data scan tool to see what the PCM is reading.

my scan tool is saying my coolant temperature is -38.2

 

[RD_Atlanta]

Do you have an ohm meter? Try measuring the resistance of the ECT across both conductors on the sensor and post what you measure. It is a thermistor with a negative temperature coefficient, meaning its resistance decreases as temperature increases. If the problem is the ECT sensor, I would expect a very high resistance (approaching 100k ohms or possibly higher). I don't know how cold it is where you are but let's assume its near freezing; if the sensor is working, you should see somewhere in the 9k-10k ohms range. Once you know the health of the ECT, you'll know if you need to move your troubleshooting upstream.

One other point...the PCM is reporting that it 'thinks' the coolant temperature is very cold (according to the scanner). I would not expect the PCM to be calling the cooling fans on. Is it possible that the AC compressor is on? This is the only reason that I can think of for the cooling fans to be called. I think you should continue to pursue checking out the hardware that we have discussed here because the PCM really needs to see an approximate accurate coolant temp reading since so many PCM functions depend on an accurate reading (and currently the PCM is certainly not seeing an accurate coolant temp, according to the scanner). But it would be nice to understand why the cooling fans are being called.

 

[sliverbuick]

Do you have an ohm meter? Try measuring the resistance of the ECT across both conductors on the sensor and post what you measure. It is a thermistor with a negative temperature coefficient, meaning its resistance decreases as temperature increases. If the problem is the ECT sensor, I would expect a very high resistance (approaching 100k ohms or possibly higher). I don't know how cold it is where you are but let's assume its near freezing; if the sensor is working, you should see somewhere in the 9k-10k ohms range. Once you know the health of the ECT, you'll know if you need to move your troubleshooting upstream.

One other point...the PCM is reporting that it 'thinks' the coolant temperature is very cold (according to the scanner). I would not expect the PCM to be calling the cooling fans on. Is it possible that the AC compressor is on? This is the only reason that I can think of for the cooling fans to be called. I think you should continue to pursue checking out the hardware that we have discussed here because the PCM really needs to see an approximate accurate coolant temp reading since so many PCM functions depend on an accurate reading (and currently the PCM is certainly not seeing an accurate coolant temp, according to the scanner). But it would be nice to understand why the cooling fans are being called.

got it i’m gonna go get a pcm scanner and ill post what the scanner says

 

[RD_Atlanta]

I apologize if I misunderstood, I thought the scan tool is reporting -38.2 deg ? If that's the case, you wouldn't need a scanner, instead troubleshooting with a multimeter.

 

[MelsRegal]

my scan tool is saying my coolant temperature is -38.2

What happens when you manipulate the wire harness, engine running, watching scan tool

 

[sliverbuick]

I apologize if I misunderstood, I thought the scan tool is reporting -38.2 deg ? If that's the case, you wouldn't need a scanner, instead troubleshooting with a multimeter.

i just bought a pcm scanner and i scanned the pcm and it’s reading two codes the first one is ECT Sensor Circuit High Voltage and the second code is ECT Sensor Circuit Intermittent High Voltage so what does these codes mean?

 

[sliverbuick]

I apologize if I misunderstood, I thought the scan tool is reporting -38.2 deg ? If that's the case, you wouldn't need a scanner, instead troubleshooting with a multimeter.

i just bought a pcm scanner and i scanned the pcm and it’s reading two codes the first one is ECT Sensor Circuit High Voltage and the second code is ECT Sensor Circuit Intermittent High Voltage so what does these codes mean

What happens when you manipulate the wire harness, engine running, watching scan tool

the harness to the Sensor or the harness itself?

 

[sliverbuick]

What happens when you manipulate the wire harness, engine running, watching scan tool

nothing happens i just moved the harness and nothing changed

 

[RD_Atlanta]

If the sensor on the car is too difficult to access, here's a thought, try measuring the resistance of the ECT that you removed. I think this makes sense because since it appears changing the sensor made no change, it would seem that both sensors are probably good and should measure about the same.

 

[MelsRegal]

Do you have an ohm meter? Try measuring the resistance of the ECT across both conductors on the sensor and post what you measure. It is a thermistor with a negative temperature coefficient, meaning its resistance decreases as temperature increases. If the problem is the ECT sensor, I would expect a very high resistance (approaching 100k ohms or possibly higher). I don't know how cold it is where you are but let's assume its near freezing; if the sensor is working, you should see somewhere in the 9k-10k ohms range. Once you know the health of the ECT, you'll know if you need to move your troubleshooting upstream.

One other point...the PCM is reporting that it 'thinks' the coolant temperature is very cold (according to the scanner). I would not expect the PCM to be calling the cooling fans on. Is it possible that the AC compressor is on? This is the only reason that I can think of for the cooling fans to be called. I think you should continue to pursue checking out the hardware that we have discussed here because the PCM really needs to see an approximate accurate coolant temp reading since so many PCM functions depend on an accurate reading (and currently the PCM is certainly not seeing an accurate coolant temp, according to the scanner). But it would be nice to understand why the cooling fans are being called.

Any time there is a cooling system related code it goes into fail safe mode and turns on the fans

 

[RD_Atlanta]

Any time there is a cooling system related code it goes into fail safe mode and turns on the fans

That's good to know, thank you. So please disregard my unnecessary diversion, it's down to an ECT, wiring / connector or the PCM analog input.