temperature display

[Trouttrooper]

I've noticed that occasionally my rearview mirror temp display will flash "ICY" for about 10 seconds.

 

I know you've got vast experiance with this in Florida but what makes it do this? I use to think it was when the temp was falling and as it got close to freezing it was just a reminder.

 

However, on my last road trip the temp fluctuated from 55F to 20F as I was going up and down hills and it never did flash "ICY" (my passengers in the back seat thought it was just neater then heck to watch the temp change so I know we didn't miss seeing it).

 

Then the other day as I was heading to town the temp started at -7F and went down to -15F. Halfway there (30 miles) it started flashing "ICY". My thought was well DUH!

 

Oh ya, '05 3500 LS. It's not a major concern, I'm just curious now what conditions make it flash "ICY".

[GM-Tech]

I'm just curious now what conditions make it flash "ICY".

 

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Here's from our service information's "Description and operation" of the mirror...

 

"In cold temperatures such as 3°C (37°F) or below, the temperature display will show ICE when the ignition is first turned ON. The display will toggle between ICE and the actual outside temperature until the temperature update process is complete."

 

And, here's the temperature update process. It's a little more complex than one might imagine...

 

"The inside rearview mirror has a temperature program that takes in account the fact that the radiator will heat the ambient air temperature sensor if the radiator is warm and the vehicle is not moving. If the vehicle has been off for more than 2 hours, the mirror temperature program assumes that the radiator has cooled and that the temperature supplied by the ambient air temperature sensor is accurate. Because of this, if the vehicle has been off for more than 2 hours, the mirror displays the temperature as reported by the ambient air temperature sensor. When the ambient air temperature sensor reports a new temperature to the mirror, one of the following cases will apply:

 

• Ignition is OFF for more than 2 hours, then is turned ON for more than 3 minutes. The outside temperature is greater than the last temperature recorded by the mirror for 2 minutes. The mirror will increase the last temperature reading by one degree every 2 minutes for 8 consecutive times. If the outside temperature is not matched after the 8th update, the mirror will then display the current outside temperature.

 

• Ignition is off for more than 2 hours, then is turned ON for less than 3 minutes. The mirror will update the temperature display every 2 seconds.

 

• Ignition is OFF for more than 2 hours, then is turned ON for more than 3 minutes. The outside temperature is less than the last temperature recorded by the mirror. The mirror will then display the current outside temperature.

 

• Ignition has been OFF for less than 2 hours. The outside temperature is greater than the last temperature recorded by the mirror, but the ignition is cycled from ON to OFF within 2 minutes. The mirror will display the old temperature.

 

• Ignition has been OFF for less than 2 hours. The outside temperature is less than the last temperature recorded by the mirror. The mirror will then display the current outside temperature. "

[Trouttrooper]

I'm just curious now what conditions make it flash "ICY".

 

<{POST_SNAPBACK}>

 

 

 

Here's from our service information's "Description and operation" of the mirror...

 

"In cold temperatures such as 3°C (37°F) or below, the temperature display will show ICE when the ignition is first turned ON. The display will toggle between ICE and the actual outside temperature until the temperature update process is complete."

 

And, here's the temperature update process. It's a little more complex than one might imagine...

 

"The inside rearview mirror has a temperature program that takes in account the fact that the radiator will heat the ambient air temperature sensor if the radiator is warm and the vehicle is not moving. If the vehicle has been off for more than 2 hours, the mirror temperature program assumes that the radiator has cooled and that the temperature supplied by the ambient air temperature sensor is accurate. Because of this, if the vehicle has been off for more than 2 hours, the mirror displays the temperature as reported by the ambient air temperature sensor. When the ambient air temperature sensor reports a new temperature to the mirror, one of the following cases will apply:

 

• Ignition is OFF for more than 2 hours, then is turned ON for more than 3 minutes. The outside temperature is greater than the last temperature recorded by the mirror for 2 minutes. The mirror will increase the last temperature reading by one degree every 2 minutes for 8 consecutive times. If the outside temperature is not matched after the 8th update, the mirror will then display the current outside temperature.

 

• Ignition is off for more than 2 hours, then is turned ON for less than 3 minutes. The mirror will update the temperature display every 2 seconds.

 

• Ignition is OFF for more than 2 hours, then is turned ON for more than 3 minutes. The outside temperature is less than the last temperature recorded by the mirror. The mirror will then display the current outside temperature.

 

• Ignition has been OFF for less than 2 hours. The outside temperature is greater than the last temperature recorded by the mirror, but the ignition is cycled from ON to OFF within 2 minutes. The mirror will display the old temperature.

 

• Ignition has been OFF for less than 2 hours. The outside temperature is less than the last temperature recorded by the mirror. The mirror will then display the current outside temperature. "

 

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Wow! the person in charge of thermometers at GM must be really bored.

 

 

Thanks for the reply

[GM-Tech]

Wow! the person in charge of thermometers at GM must be really bored.

 

Not really. If they didn't account for all possibilities, we have customers come in complaining, "My mirror temperature is off sometimes! That's unacceptable!"

 

I'm curious as to why you blur your tag (license plate) number in that photo? Hundreds of people a day see it when you're driving around.

[Trouttrooper]

I'm curious as to why you blur your tag (license plate) number in that photo?  Hundreds of people a day see it when you're driving around. 

 

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C.Y.A. cop attitude. Just simple steps to protect my family. Don't want to make it too easy for bad guys to find me.

 

I put at most 10,000 miles a year on my personal truck. Doesn't leave the driveway too much. Nearest neighbor is 3/4 mile away.