2019 Sierra Elevation - BLOCK HEATER TROUBLE

[Almasp]

I was worried initially there was something wrong with my block heater, but upon further reading I see that GM restricts use to -18^oC.

If there's any reason I shouldn't activate my heater above -20, I'm all ears, but that seems a little ridiculous, and personally I'd rather pre-heat for a couple hours than idle in the driveway for 10 minutes. I paid for the heater after all.

After some testing, it appears my system has the thermostat on-board rather than on the plug. No continuity at the element plug, and cord is 545324639, used for the diesels which have a heater tuned for temperatures much warmer than -18. 

Now, from what I can find, the heating element (12586687) doesn't look like it has the space for an thermostat. 

If the thermostat isn't in my cable, and isn't in the heating element, is it within the wiring harness (86827721) from plug-to-element?

Or if it's not in there, where is it?
How can I bypass the block heater thermostat??

Edited February 22, 2025 by Almasp

[CamGTP]

The earlier trucks, probably back like over 10 years ago had the thermostat in the plug, those were super easy to bypass. The only problems that some people could run into was like a coolant temp vs air temp mismatch code because the temps didn't align for the given ambient temps when the computer knew it wasn't cold enough. I only got that a few times but then I used my tuning software to turn that code off forever.

 

I think the thermostat or whatever they are using is in the wiring harness now. A test could be to just buy a generic block heater cord or find one to borrow and plug it into the stock block heater unit, then plug it into the wall. See if it turns on that way.

 

I bet in GM's eyes, they just think that above that temp it's not needed for safe vehicle function.

[Almasp]

1 minute ago, CamGTP said:

The earlier trucks, probably back like over 10 years ago had the thermostat in the plug, those were super easy to bypass. The only problems that some people could run into was like a coolant temp vs air temp mismatch code because the temps didn't align for the given ambient temps when the computer knew it wasn't cold enough. I only got that a few times but then I used my tuning software to turn that code off forever.

 

I think the thermostat or whatever they are using is in the wiring harness now. A test could be to just buy a generic block heater cord or find one to borrow and plug it into the stock block heater unit, then plug it into the wall. See if it turns on that way.

 

I bet in GM's eyes, they just think that above that temp it's not needed for safe vehicle function.

Thanks for reply. 

I'm about to test my cable for continuity at room temp (it looks like its the non-thermostat cable though).

If my thermostat is in the harness under the hood, is there anything to note before I snip it out? Or is that going to end up working exactly the same as cutting it out of a thermostat cable?

[redwngr]

The diesel supplement to the owners manual also says to use the block heater when below 0F / -18C.

 

Fwiw, the 3.0 starts fine, unassisted, below 0F.

I've not even unwrapped the block heater cord. 

 

Block heater is standard/included with the 3.0

Edited February 22, 2025 by redwngr

[silveradosid]

i agree with Almasp, it would be nice to preheat the engine. it is not wether it will start or not, some times i have to use my remote start twice to get heat