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From my manual: "an internal thermostat in the plug-end of the cord may exist which will prevent engine coolant heater operation at temps above -18." How do I know if mine has this thermostat? and if it does, how do I disable it? I want mine heating by -10.

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It's some kind of blister-looking thing on the plug end. I do not have one but from what I understand bypassing it might cause the check engine light to come on as the truck will "see" the disparity between air temp and coolant temp and set a code. Only below the temp specified in the manual is that not an issue supposedly. However I do not have a block heater and am only going off what I've read here.

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It's easy to tell if you have it or not. If you cord end looks like it has tumor........ you have it. If it's a standard male cord end you don't. Just cut the thing off and replace with regular cord end. That said I have never done it on any of my trucks to see if I actually get a code triggered. The code it could set would be timer based in conjunction with the IAT sensor reading. Seems like a lot of trouble for nothing for GM but I see the point of detecting a failing CTS.

 

Basically though, if you replace the end of the cord and then only have it plugged in when it's actually below 20F or so..... it probably will never trigger any code and you have a guarantee of a warmer block... It just lets the pistons move slightly easier in the cylinders as it does nothing for the oil in the pan of course.

 

It's funny when the weather hovers at the 0 F mark..... I can noticeably tell when my block heater cord has passed power and when it hasn't as the truck does labour a bit more when it hasn't. That is with 5W30 Amsoil synthetic in it as well.

Edited by Notamember

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There are several things you can do. Two of which I have done myself.

 

Any of these 3 options will cause the block heater to now be energized whenever it is plugged in :

 

1 - You can cut open the small round end of the blister and stick a scrap metal washer in there and re-seal it with tape or silicone. The washer makes contact with both sides and defeats the bi-metallic sensor.

2 - You can cut the thermostat blister completely off and install an new male 3-prong plug (all hardware stores carry them).

3 - You can go to NAPA and order a new, non-thermostatic cord and replace the entire cord from the block heater forward. They come in different length's and you can get a longer one if that works better for you. Look at the cord before you take it home to make sure it has the correct orientation on the block heater end, and is the length you want. NAPA has a bunch of different ones to suit your needs

 

I have personally done #1 and 3 above. The only possible issue with #2 above is getting a weatherproof rated one and keeping out corrosion.

 

I have never had the block heater operation set a MIL code, but I don't plug it in if the temp is above +15F. I've been doing this sine 2005.

 

No worries.

 

DEWFPO

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I wonder why some have the thermostat and others don't. My 2005 Dmax does not have the thermostat and when I plug it in I almost instantly hear the block heater energize.

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My 2005 came with a thermostat on the block heater cord, but the block heater was an option that I ordered on the 8.1L.

 

DEWFPO

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Not to highjack the thread but does anyone know where the block heater cord is for a 2012 duramax? Doesn't appear to be in the same place as my old 2005

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It's usually coiled up underwood someplace.

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wurgs,

I would be happy to look into this for you with the last eight of your VIN. Feel free to contact me privately for more assistance. Thank you.

 

Tricia, GM Customer Service.

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Not to highjack the thread but does anyone know where the block heater cord is for a 2012 duramax? Doesn't appear to be in the same place as my old 2005

 

 

on my 2013 its on the passenger side taped to a harness by the fender. It was a pain to get the zip tie cut

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My cord is not where the manual says it should be.... I am afraid that my truck does not have a coolant heater. I am sure that my truck, working in Louisiana in its prior life, never needed a coolant heater. But I am disappointed that I don't have it now that I need it. Does anyone here have advice on installing an after-market heater? Thanks

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My cord is not where the manual says it should be.... I am afraid that my truck does not have a coolant heater. I am sure that my truck, working in Louisiana in its prior life, never needed a coolant heater. But I am disappointed that I don't have it now that I need it. Does anyone here have advice on installing an after-market heater? Thanks

What engine?

 

ALL Duramaxes have a block heater.

 

The cord is tie wrapped under the air piping on the passenger side of the engine compartment. (on the engine side of the wheel well liner) It's sometimes hard to find, but it'll be under there.

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Thanks redwngr Found it.

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