What is this?
09-23-2014, 12:59 PM
#11
JK Jedi Master
So, Ron, why is it that the ambient air temp doesn't update until you hit about 30 MPH? On some of my overlanding trips, I can be three or four days before ever hitting 30 MPH! LOL.
09-23-2014, 01:01 PM
#12
JK Junkie
Well I live in FL and the temp readout is typically 10 to 20 degrees higher than the ambient temperature at startup. The manual said it will take a few minutes to adjust before being accurate. I have found this to be true. However, it also states that it is inaccurate at first because it is retaining the last temperature reading when you turned it off. This is the part that doesn't seem accurate.
09-23-2014, 01:10 PM
#13
JK Jedi Master
Here is how it works, followed by my testing for accuracy:
Vehicle with the key off for more than 4 hours ...The CCN will update the ambient temperature reading immediately.
Vehicle with key off for more than 2 hours but less than 4 hours....The CCN will update the ambient temperature reading immediately after vehicle reaches above 20 mph (with no duration constraint) and will update every 500 ms thereafter.
Vehicle with the key off for less than 2 hours...The CCN will
display the last temperature reading (which is stored in memory) just prior to the ignition being turned off. The CCN will not update the value in the display until the car has been driven at 20 MPH or above for 3 consecutive minutes. If the vehicles speed and drive time does meet the criteria the CCN will
continue to display the stored value until the criteria is met. Once the criteria is met, then the CCN will update the display every 500 ms based off of the ambient temperature sensor output.
I did some tests.
I have two thermometers.
One is calibrated and certified. (Alcohol Thermometer)
The other has a year long history of reading the same as the calibrated one, when sitting next to it. (Mercury Thermometer)
I taped the mercury thermometer next to the JK sensor.
The alcohol thermometer was in the passenger's front seat.
All the windows were open. It was a heavily overcast day.
After about 10 minutes of driving, I noted the following results.
The JK display read 70°F
The thermometer next to the sensor read 72°F
The thermometer in the cab read 71.5
After the return trip, I noted the following results.
The JK display read 69°F
The thermometer next to the sensor read 71°F
The thermometer in the cab read 71°F
After I parked and shut off the engine, I put the thermometer that was in the cab, next to the one by the JK sensor.
After 5 minutes, both test thermometers read 78°F. (Engine heat radiating from grill.)
09-23-2014, 01:22 PM
#15
JK Jedi Master
Not during the tests quoted. I have since noticed the JK's ambient temp reading after sitting all night is pretty close to the thermometer reading I see at the back door of the house, and also pretty close to the transmission temp reading.
Last edited by ronjenx; 09-23-2014 at 01:24 PM.
09-23-2014, 01:22 PM
#16
JK Jedi Master
The temp sensor programming is designed to make it less likely the readout will include any heat from the engine bay.
Here is how it works, followed by my testing for accuracy:
Vehicle with the key off for more than 4 hours ...The CCN will update the ambient temperature reading immediately.
Vehicle with key off for more than 2 hours but less than 4 hours....The CCN will update the ambient temperature reading immediately after vehicle reaches above 20 mph (with no duration constraint) and will update every 500 ms thereafter.
Vehicle with the key off for less than 2 hours...The CCN will
display the last temperature reading (which is stored in memory) just prior to the ignition being turned off. The CCN will not update the value in the display until the car has been driven at 20 MPH or above for 3 consecutive minutes. If the vehicles speed and drive time does meet the criteria the CCN will
continue to display the stored value until the criteria is met. Once the criteria is met, then the CCN will update the display every 500 ms based off of the ambient temperature sensor output.
I did some tests.
I have two thermometers.
One is calibrated and certified. (Alcohol Thermometer)
The other has a year long history of reading the same as the calibrated one, when sitting next to it. (Mercury Thermometer)
I taped the mercury thermometer next to the JK sensor.
The alcohol thermometer was in the passenger's front seat.
All the windows were open. It was a heavily overcast day.
After about 10 minutes of driving, I noted the following results.
The JK display read 70°F
The thermometer next to the sensor read 72°F
The thermometer in the cab read 71.5
After the return trip, I noted the following results.
The JK display read 69°F
The thermometer next to the sensor read 71°F
The thermometer in the cab read 71°F
After I parked and shut off the engine, I put the thermometer that was in the cab, next to the one by the JK sensor.
After 5 minutes, both test thermometers read 78°F. (Engine heat radiating from grill.)
Here is how it works, followed by my testing for accuracy:
Vehicle with the key off for more than 4 hours ...The CCN will update the ambient temperature reading immediately.
Vehicle with key off for more than 2 hours but less than 4 hours....The CCN will update the ambient temperature reading immediately after vehicle reaches above 20 mph (with no duration constraint) and will update every 500 ms thereafter.
Vehicle with the key off for less than 2 hours...The CCN will
display the last temperature reading (which is stored in memory) just prior to the ignition being turned off. The CCN will not update the value in the display until the car has been driven at 20 MPH or above for 3 consecutive minutes. If the vehicles speed and drive time does meet the criteria the CCN will
continue to display the stored value until the criteria is met. Once the criteria is met, then the CCN will update the display every 500 ms based off of the ambient temperature sensor output.
I did some tests.
I have two thermometers.
One is calibrated and certified. (Alcohol Thermometer)
The other has a year long history of reading the same as the calibrated one, when sitting next to it. (Mercury Thermometer)
I taped the mercury thermometer next to the JK sensor.
The alcohol thermometer was in the passenger's front seat.
All the windows were open. It was a heavily overcast day.
After about 10 minutes of driving, I noted the following results.
The JK display read 70°F
The thermometer next to the sensor read 72°F
The thermometer in the cab read 71.5
After the return trip, I noted the following results.
The JK display read 69°F
The thermometer next to the sensor read 71°F
The thermometer in the cab read 71°F
After I parked and shut off the engine, I put the thermometer that was in the cab, next to the one by the JK sensor.
After 5 minutes, both test thermometers read 78°F. (Engine heat radiating from grill.)
09-23-2014, 01:35 PM
#18
JK Junkie
Edit: My wife's 2012 is the same way. She'll tell me it was 112 when she got in the Jeep. I'll tell her you can't go by that what was the temp when you got home. She'll answer 94 (which is correct).
Last edited by 14Sport; 09-23-2014 at 01:47 PM.
09-23-2014, 02:00 PM
#19
JK Jedi Master
Same results here in FL. However, when I leave for work in the morning during the summer it is typically high 70s or low 80s and the display appears correct. I work about 8 miles of city driving from my house. The temp seems accurate when I shut the Jeep off at work. Eight hours later, when starting the jeep it can say anything from high 90s to low 100s (even 110 to 115 sometimes). After a few minutes it drops to the ambient temp of low to mid 90s. Any idea what may be going on here? Does it continue to read for a few minutes after I shut it off (now being affected by engine heat)? Or can just backing into my parking spot cause it to read higher but not record on the readout?
Edit: My wife's 2012 is the same way. She'll tell me it was 112 when she got in the Jeep. I'll tell her you can't go by that what was the temp when you got home. She'll answer 94 (which is correct).
Edit: My wife's 2012 is the same way. She'll tell me it was 112 when she got in the Jeep. I'll tell her you can't go by that what was the temp when you got home. She'll answer 94 (which is correct).
Last edited by ronjenx; 09-23-2014 at 02:02 PM.
09-23-2014, 02:04 PM
#20
JK Junkie
