[Hud477]

Looking for help.

Have a 2002 Chevy Trailblazer 160k on it. Today replaced thermostat, coolant temp sensors, water pump and fan clutch. Took it apart and got everything back together fine. Filled it with coolant and started her up. She ran for about 2 minutes and conked out.

Got code p0118 for the coolant temperature sensors. Tried to start it up but now she sputters and won’t start.

I just don’t get it seemed like everything went as planned putting back together.
🤷🏻‍♂️🤦‍♂️

Any advice appreciated.

 

[VoyBoy919]

I know it sounds silly, but make sure nothing was accidentally unplugged during teardown that shouldn't have been, especially the throttle body plug. Also, I've seen a lot of people answer that the throttle body, fan wiring and a couple other things run off the same 5volt source, so make sure that the fan plug beside the radiator was plugged in correctly. Unplug it and check the pins to see if any are bent, and that the harness is intact. I dont know if the coolant sensors have any ability to tell the cpu to cut the engine off or not, fir instance if they are bad(even though new they can be bad,) but I'm sure you could Google that until someone more knowledgeable on those sensors posts an answer for you.

 

[VoyBoy919]

I did a quick search and I found a thread that said the coolant system might throw a code but not actually cause your engine NOT to start. But then another said that if it's not reading correctly it can cause a rich condition and make it hard to start. I would say try to unplug the coolant sensor(s) that you just replaced, abd try to start the engine again. If it starts with them unplugged, you might have gotten a bad sensor..and check the harness fir the sensors also.

 

[Ravalli Surfer]

If you suspect it's flooded, just floor the throttle and crank in WOT-Clear Flood Mode.

If it starts during this time be sure to release the throttle to let it return to idle.

You cannot actually get the engine to rev so high it can hurt itself --- it SHOULD hold the revolutions around 3K RPM or sometimes a little less.

 

[Vega_TB]

P0118 Engine Coolant Temperature (ECT) Sensor Circuit High Voltage
Conditions: The ECT sensor temperature is less than -39°C (-38°F) for more than 6 seconds.

There is some problem with the temperature sensor.
What brand did you use? Be aware this may be new but already bad from the store.
Have you tried clearing the error code?
Report after erasing the error, does the car start again?

 

[Hud477]

I ordered GM genuine for sensors, but I think the package said dayco. It was like 35 bucks on rock auto. Yeah cleared the codes and now trying to start it up will, turn the key and will just sputter and not start.

 

[Vega_TB]

Are you getting any other codes? Did you use any means to protect the contacts from corrosion when assembling the electrical connections? Do you have experience with DDM?

 

[Ravalli Surfer]

P0118 Engine Coolant Temperature (ECT) Sensor Circuit High Voltage
Conditions: The ECT sensor temperature is less than -39°C (-38°F) for more than 6 seconds.

There is some problem with the temperature sensor.
What brand did you use? Be aware this may be new but already bad from the store.
Have you tried clearing the error code?
Report after erasing the error, does the car start again?

Is -36°F a default value for either a disconnected ECT or a bad unit internally or an intermittent contact?

I had always known that -45°F was the old original default --- but -36°F might be the new default.

ON a Pontiac GrandAm I once found a swinging temp wire that at just the right combination of things, would move by underhood wind and/or vibration and physically pull on a corroded connex that caused me to pull my hair for a while.

"Wiggle tests" never found the problem, but I kept coming back to the old rule "don't touch it until you diagnose it" - in that it's never a good idea to go under the hood and indescriminatedly start yanking on wires and connectors.

Odd things like that keep one humble --- one of my greatest traits -------> being humble.

 

[VoyBoy919]

Any input from discussion starter???

 

[Ravalli Surfer]

I just noticed the OPs handle: Hud.

Any relation to Royce David Huddleston?

 

[Vega_TB]

Is -36°F a default value for either a disconnected ECT or a bad unit internally or an intermittent contact?

I had always known that -45°F was the old original default --- but -36°F might be the new default.

ON a Pontiac GrandAm I once found a swinging temp wire that at just the right combination of things, would move by underhood wind and/or vibration and physically pull on a corroded connex that caused me to pull my hair for a while.

"Wiggle tests" never found the problem, but I kept coming back to the old rule "don't touch it until you diagnose it" - in that it's never a good idea to go under the hood and indescriminatedly start yanking on wires and connectors.

Odd things like that keep one humble --- one of my greatest traits -------> being humble.

For engines 4.2, 5.3 and 6.0 that were installed on the TV, the conditions for triggering the P0118 code are slightly different.
For 4.2L
The ECT sensor temperature is less than --38°F for more than 6 seconds.
For 5.3L and 6.0L
The ECM detects that the ECT sensor parameter is less than --40°F for 5 seconds.
However, for subsequent diagnostics in the process of identifying a malfunction for all three types of engines, a value of 39°F is declared
This is what you should check on the scanning device.

P.S It is necessary to understand why the car does not start.

 

[Ravalli Surfer]

For engines 4.2, 5.3 and 6.0 that were installed on the TV, the conditions for triggering the P0118 code are slightly different.
For 4.2L
The ECT sensor temperature is less than --38°F for more than 6 seconds.
For 5.3L and 6.0L
The ECM detects that the ECT sensor parameter is less than --40°F for 5 seconds.
However, for subsequent diagnostics in the process of identifying a malfunction for all three types of engines, a value of 39°F is declared
This is what you should check on the scanning device.

P.S It is necessary to understand why the car does not start.

Thank-you very much for that info. It's news to me that there would be differeing values for different engines/computers.

The -45°F was always the value I was told to watch for as that would sometimes keep an engine from starting (serious flooding) and/or cause it to stall from over-rich condition --- but that latter part "over rich" and "stall" never made sense to me since you can always blip the throttle if you are of the mindset to do so ... to clear the engine to run after clearing it's throat, so to say. ''

Ostensibly the -45°F rule is not, in this situation, being set by the sensor --- only if it internally goes OPEN and reports ZERO Resistance.... not unlike a broken wire or connection somewhere. I said that for persons who might not be in the loop in which we are for a lesson here -- and again: I thank you for the clarification.

I digress ----> -45°F always made sense to me as it's a pretty bad winter temperature or you live at one of the poles for that to happen, so as a default --- it makes sense. Having a higher threshold (-38°F) kinda stretches my imagination ... but, hell .... I'm OK with it .... I guess.

FTR - we can get to -39°F in parts of Montana - thankfully, not where I am though.