Blockheater makes guage not work

[jonny72888]

Hey guys! Today was the first day I used my block heater on my truck. I turned it on about 2 hours before I left and when I started it the gauge was alittle above 160. As I was driving the gauge dropped to zero (bottomed out) and stayed there. So I get home and plug my reader in to see what the temp is and it show I have a code. (p0107 I think) saying the my temp sensor had a mis read. Im guessing this is from when I the block heater warmed up the truck and the truck had no clue it was doing it. So my question is what would make this happen all the sudden. last year I used it almost every day and this never happened. The only thing that has changed was I not have a new pcm.. could that be it?

 

Oh, and after I cleared the code the gauge works just fine.

[Silverado4x4]

Read your owners manual I think it says not to use them unless the temp drops below 24 degrees or something like that at least that what it said when I had my Duramax which I never had to use.

[dewfpo]

What was the ambient temp when you unplugged the block heater? You likely crossed a temperature threshold. The ECM checks coolant temp with air intake temp and trans fluid temp and compares them on a cold startup. If one of them is off by a certain amount it will trip a dash light and tell you which temp sensor is out of range.

 

It will reset itself after a certain number of cold start cycles if you don't use cross that threshold again.

 

DEWFPO

[jonny72888]

What was the ambient temp when you unplugged the block heater?

 

DEWFPO

 

About 30

[dewfpo]

What was the ambient temp when you unplugged the block heater?

 

DEWFPO

 

About 30

 

 

See my edited post above.

 

DEWFPO

[jonny72888]

So how can I use my heater?

 

[dewfpo]

That's a good question. On my '05 the block heater cord had a built in thermostat so it wouldn't come on above 0F. I assume the year they added the above thermostat to the cord is the year they decided to use the ECM to check the temp sensors. I noticed your truck is an '07, does it not have the built in thermostat in the plug? Even if I use my block heater for a 2-3 hours, the engine temperature gauge is still pegged at the cold end, but I don't use the block heater unless it fairly cold.

 

DEWFPO