So my car high temp light blinked last night after 5 minute idle. I'm thinking the fan doesn't turn on when the temp is hot. I immediately turn on the heat and AC, and the light went away after 30 seconds.

I do notice both fans turns on with AC? I also thought only 1 was suppose to turn on during AC, can anyone confirm?

 

When you say "idle 5 mins", what do you mean:
1.) Sat over night and in the morning you turned it on and left it "idle for 5 mins"?
2.) After driving home from work (25 miles) you parked it and left it "idle for 5 mins"?

If #1, no way is the engine hot enough to overheat in 5 mins unless your car is parked in hot sun in a very warm climate. I may be a little bias since it's 34 deg F here right now.

 

I was already driving and had to idle the car for 5 minutes . Did both your fans turn on with AC?

 

Again, it is 35 deg F, the car has not operated in over 24 hrs.

Upon start up, both fans run for about 10 seconds and then stop.

If I engage the A/C button, both fans turn on when the compressor engages. Then both fans turn off. I can see if the car was warmed up and the weather was 80 deg F or so, the A/C compressor, and therefore, both fans, would have to operate for a longer period of time to dissipate the heat built up in the system.

It is a lot easier for the system to cool down when the outside environment is 35 deg F than it would be at 80 - 90 deg F.

 

I just wanted to make sure my fans are operating normally before I continue disagnosing why my car overheated. So I know the fan works, cause AC turns on both fans, but probably didn't turn on automatically when it overheated.

 

Both radiator fans should always run when the AC compressor is engaged.

Both radiator fans should always run when the coolant temperature sensor in the bottom tank of the radiator reaches about 212*F.

If the coolant level in the radiator is low, that can cause overheating inside the engine without the radiator fans running.
Check that first, refill if necessary, burp air pockets from the cooling system.

 

Coolant looks good, so next step is replace coolant sensor on bottom of radiator?

 

I'd be doing some checks......

You seemed to indicate you can drive around without problems as long as you keep moving so to me that should pretty much rule out the thermostat and radiator circulation issues.

Did you check for any fault codes that may be related? (no matter if the CEL is on or not, I check anyway)

Slide under the front and inspect wiring harness, connections and wire terminals for the temp sensor in the bottom of the radiator?


If you have a generic scanner it might only display ECT ( or ECT1, the coolant temp sensor on the engine).
ECT2 is the name of the temp sensor in the bottom of the radiator.

If you have a really good scanner available, it might be able to display the ECT2 value in addition to ECT1, so you can compare and evaluate in real time.

 

Good info, if I unplug the ETC2 wire plug (plastic connector side) and wire it directly to the battery and fan turns on.... This would tell me the wired connection are good and mean the ECT2 sensor is faulty?

 

EDIT: DO NOT WIRE IT TO THE BATTERY, YOU MAY DAMAGE THE PCM

Re: Shorting the wires together:
It is an actual temperature sensor, not a thermoswitch so shorting the wires may only cause a fault code for the unexpected voltage input.
(ECT2 related fault codes: P2183, P2184, P2185)
I saw nothing in my info saying the fans would turn on by shorting the wires, so I would not expect them to turn on if you try it.

You can use a voltmeter to check the wiring for that sensor though...One wire should show 5v coming from the PCM, the other wire should be ground. That would verify wiring is intact between the PCM and the sensor.

 

I appreciate your help through this. So I attempted to short the connection but no result (as you expected). I'll try a volt meter on it next. If volt meter returns positive, must be temp sensor.

I did test out the following. Pulled the sub blower fuse and turn on AC resulted in only driver side fan turning on, sounds normal to you?

 

The wiring diagrams aren't always labeled with the same names as the fusebox IDs in the car.


Looking at the 2010 M.Y. diagrams......
If you mean you removed fuse #47 (30A) from the dash fuse panel, that would disable the condenser fan relay leaving only the radiator fan to run when both are commanded on by the PCM.

(On that car, the Condenser fan is on the passengers side, right side of the engine compartment. Radiator fan is on the drivers, the left side.)

 

Yes pulled fuse #47.

I can report i'm getting about 4.9v from the multimeter. So it appears the next step is replace the coolant sensor.

 

Other wire (ohm) tests as a ground?

 

Honesty this is my first time using a mulitmeter, I'm not very good with it. I turn on the DC V switch and connected the wires to the connector. So i'm not sure if I tested it as ground.

 

Test:

One meter lead connected to the battery negative terminal, the other meter lead to the wire being tested. Ohms scale, lowest setting. Should read near zero ohms. That would equal continuity to ground.

Also, I sure hope you aren't trying to stuff the tip of the meter lead into the female terminals in the connector, you can damage them easily.
Simply make the probe contact with the exposed metal in the terminal....I usually use paper clips as my test probe (my meter leads have alligator clips), or dedicated specifically sized wire terminals.


Did you ever check for fault codes?

 

Just wanted to report fan is now turning on during idle. The CEL never lighted up, I just replaced the temp sensor under radiator. Thanks for your help in this matter.