[Eldi Z]

Please post the Temperatures you see, normal daily (not track) when:

- Fan kicks in at its 1st speed
- Fan stops

- Fan kicks in at its 2nd (full blast)
- Fan stops

Trying to de-bug a recent issue I am seeing with the fan suddenly blowing full speed, Coolant Temp gauge pegging at the minimum reading, AC compressor disabled, Rad. fan keeps blowing full speed, even when shutting ignition off and locking the doors:

From what I have learned, this means ECM triggers "Safe Mode". I diagnosed P0119 (Temperature Circuit Intermittent).
Obviously no real overheating occurs - Coolant is full, engine runs as usual. No sign of heat, Etc.. After re-starting, gauge also displays as usual, correct Temp reading at ~ 190-195 fan

So it could mean that there is either some moisture accumulating in one of the relays, or another short-to-ground anywhere in the circuitry of the ECT (Temp sensor) signal.
Something else I read about is the OBD connector wiring is sometimes susceptible to electromagnetic influences and can cause all kinds of unexpected issues of this sort to pop up.

Anyone with ideas of experience please chime in.

[Pollock]

I have no help to offer but are you trying to fix it yourself or can the dealer not figure it out? Would think you have a warrenty. Just curious.

[Boost Creep]

Originally Posted by Eldi Z

Please post the Temperatures you see, normal daily (not track) when:

- Fan kicks in at its 1st speed
- Fan stops

- Fan kicks in at its 2nd (full blast)
- Fan stops

Trying to de-bug a recent issue I am seeing with the fan suddenly blowing full speed, Coolant Temp gauge pegging at the minimum reading, AC compressor disabled, Rad. fan keeps blowing full speed, even when shutting ignition off and locking the doors:

From what I have learned, this means ECM triggers "Safe Mode". I diagnosed P0119 (Temperature Circuit Intermittent).
Obviously no real overheating occurs - Coolant is full, engine runs as usual. No sign of heat, Etc.. After re-starting, gauge also displays as usual, correct Temp reading at ~ 190-195 fan

So it could mean that there is either some moisture accumulating in one of the relays, or another short-to-ground anywhere in the circuitry of the ECT (Temp sensor) signal.
Something else I read about is the OBD connector wiring is sometimes susceptible to electromagnetic influences and can cause all kinds of unexpected issues of this sort to pop up.

Anyone with ideas of experience please chime in.

Coolant sensor going full cold is usually an open, not short to ground in the sensor circuit.
Did you actually have a P0119, or just using that as a starting point?
Good luck.

[Eldi Z]

Originally Posted by Pollock

I have no help to offer but are you trying to fix it yourself or can the dealer not figure it out? Would think you have a warrenty. Just curious.

Warranty is in place of course. Car has only 4200 miles so far.

However, I usually like to go to the dealer prepared with information / back-up material, since the dealers usually have little clue on the more complicated matters and especially "Intermittent" types like these.

They tend to "send you back home" telling everything is O.K. and that they did not observe anything out of the ordinary, unless I get "lucky" and exactly when the car is being checked on their premises, the phenomena is going to occur.

[Eldi Z]

Originally Posted by Boost Creep

Coolant sensor going full cold is usually an open, not short to ground in the sensor circuit.
Did you actually have a P0119, or just using that as a starting point?
Good luck.

I did actually see the "Coolant Circuit Intermittent" DTC on the scanner at my friends shop. He is a specialized vehicle electrician...
I even had the MIL light up and cleared the code.

What are you referring with "sensor going full cold" ?
Actually, the way I understood it, when there is either a short OR an open circuit (one of them), then this "safe mode" (with the fan full blast, AC disabled and Temp Gauge pegged "Min".) happens.

I read somewhere that the OBD connector wiring in GM vehicles in general can sometimes be the culprit when certain magnetic fields are picked up by them.
I suspect this could be the case as well, since I use a special device in my job that involves magnets and I carry it in my car.
I shall try to move it out of the car and observe if this "safe mode" does not re-occur.
If it does, then obviously I must keep on looking.
Also, I have a tracking system (Anti Thefts related) installed and the installer obviously had to use the +12V power source/s from the wiring for both "before" and "after" switch (starter). I shall check this route as well.

Thanks for your inputs so far. any idea or experience will be appreciated by a happy new Black-on-Black 1LE owner

[Eldi Z]

+ can you add your observations regarding the fan kick-in and shut-off temps?
Would like to compare with what I see when everything is "normal"

[Boost Creep]

Originally Posted by Eldi Z

What are you referring with "sensor going full cold" ?
Actually, the way I understood it, when there is either a short OR an open circuit (one of them), then this "safe mode" (with the fan full blast, AC disabled and Temp Gauge pegged "Min".) happens.

Usually when the coolant temp sensor has an open in the wiring, the gauge goes to full cold or as you put it "min". That however wouldn't make your fans run like it was hot/overheating.

I've only got about 300 miles on my car, only drove it twice, three times if you consider the dealer test drive, so I don't have any relevant info to add about the fan settings.

Though the two times I did start it, the car seemed to warm up incredibly fast.

[Eldi Z]

Originally Posted by Boost Creep

Usually when the coolant temp sensor has an open in the wiring, the gauge goes to full cold or as you put it "min". That however wouldn't make your fans run like it was hot/overheating.

I've only got about 300 miles on my car, only drove it twice, three times if you consider the dealer test drive, so I don't have any relevant info to add about the fan settings.

Though the two times I did start it, the car seemed to warm up incredibly fast.

Thanks.
Well, the "Safe Mode" involves all these things at once: Fan full blast, Gauge right at full-cold and AC Compressor not kicking in.
I doubt it is an "Open Wire" case, since I went over the wiring and could not find anything out of the ordinary.
Following possibilities likely:
1.) Intermittent short to ground somewhere (Tracking system voltage connections)
2.) Bad sensor (shorting intermittently inside) - Very unlikely since 8 months & 4 K miles car
3.) Magnetic field influencing the OBD wiring to the ECM causing this fluke

[Saybo]

So, this has happened twice to me. Both times I was fiddling with my CAI.

The first time was after I was done installing my intake. I turned the car on and the fan immediately went full blast. Turned the car off and on again and there was no issue.

The second time this happened was when my air filter fell off while I was driving and the car was idling weird. I pulled over and reattached my intake and tightened it down. When I turned the car on again the fan kicked on full blast. Turned the car off and on and it went away. Haven't had this issue since.

[Boost Creep]

Originally Posted by Saybo

So, this has happened twice to me. Both times I was fiddling with my CAI.

The first time was after I was done installing my intake. I turned the car on and the fan immediately went full blast. Turned the car off and on again and there was no issue.

The second time this happened was when my air filter fell off while I was driving and the car was idling weird. I pulled over and reattached my intake and tightened it down. When I turned the car on again the fan kicked on full blast. Turned the car off and on and it went away. Haven't had this issue since.

Ever scan for history codes in the ECU?
You may have had a code thrown but it didn't set the light because the code needs two drive cycles.

[Eldi Z]

Originally Posted by Saybo

So, this has happened twice to me. Both times I was fiddling with my CAI.

The first time was after I was done installing my intake. I turned the car on and the fan immediately went full blast. Turned the car off and on again and there was no issue.

The second time this happened was when my air filter fell off while I was driving and the car was idling weird. I pulled over and reattached my intake and tightened it down. When I turned the car on again the fan kicked on full blast. Turned the car off and on and it went away. Haven't had this issue since.

This is valuable information.
Apart from installing the CAI (which one BtW?) do you recall touching or being near to the OBD connector wiring at all?
How did your filter fall off? Isn't it a cone (I.E. K&N) type?
It could be that there is a variety of instances in which sensors pick up certain conditions that trigger the full-blast fan / Temp gauge at full cold / AC not kicking in= "Overheating Safe-Mode"
Would be interesting to know what these instances are (most likely to be).

[steelheadrob]

I am having a similar problem. Recently installed Whipple. Everything operate as expected for the first couple hundred miles. Now the coolant fans comes on full blast as soon as I start the engine and stays on until 10 minutes or so until after the car is turned off. The day I noticed I was driving back from work. I data logged it, Coolant temp never got to 160 degrees on a 25 mile drive back from work. Temp was reading in the mid to upper 150s. Trying to diagnose it today. Started the car this morning, fan still coming on as soon as I start the car, fan says it is running at 92% on the VCM scanner. As soon as I shut the car off fan stays on but drops down to 50% speed and continues to run for 10 minutes or so even though coolant temp is reading under 100. Pulled several codes, P0097 Air Intake Temp, P00F4 humidity sensor, P0118 Engine Coolant Sensor 1 Circuit High, P0128 Coolant Thermostat, P0480 Fan 1 control Circuit, P0691 Fan Control Circuit Low.

Looking at coolant temp sensor. Volts running to the sensor is just under 5 volts, seems as expected. Tested the resistance of the coolant temp sensor with it still in the car, it is reading 4.4ish not sure if that is high or low or about right. Does any know what the resistance should read with the car cold?

I am going to pull the negative on the battery and hook up a volt meter to see if I have a open circuit some where. Depending on what I find I might remove the coolant temp sensor, put some heat to it and see if the resistance changes as heat is applied. I will let you know what I find.

Any other ideas on what I should check?

[Eldi Z]

steelheadrob. What you are describing is indeed similar in terms of fans operating full speed despite not related to actual cooling requirements, but not the "Safe Mode" situation for coolant temp. circuit malfunction, which calls for 3 phenomena to take place at the same time:
1. Fan full speed and keeps operating for over 10 mins after shutting off the engine
2. Temperature gauge pegged at low (not moving at all)
3. AC Compressor never kicking in

[Eldi Z]

Originally Posted by Saybo

So, this has happened twice to me. Both times I was fiddling with my CAI.

The first time was after I was done installing my intake. I turned the car on and the fan immediately went full blast. Turned the car off and on again and there was no issue.

The second time this happened was when my air filter fell off while I was driving and the car was idling weird. I pulled over and reattached my intake and tightened it down. When I turned the car on again the fan kicked on full blast. Turned the car off and on and it went away. Haven't had this issue since.

Apart from the fan working full blast, did you also identify the following issues in addition?

- Temperature gauge pegged at low (not moving at all)
- AC Compressor never kicking in