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Post Info TOPIC: Stupid GM block heater code (temperature sensitive cord end)
4SPEED427


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Stupid GM block heater code (temperature sensitive cord end)
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Ok first off, I don't need you non-prairie guys with your "bla bla bla, what's a block heater, what's snow, etc etc etc...." biggrin

Now, to those of you who are fed up with the temp sensitive heater cords on the late model GM's (won't come on until it's colder than -18), there IS a way around it although it's a minor inconvenience.

As you likely know, if you cut off the temp sensitive cord end and put on a normal end, depending on conditions, you may end up with a check engine light and reduced power.

The way around it is this-

Cut off the cord end, put on a regular end.

Any time you plug in your car IF it's not colder than about -18, you have to start your car in the morning, then shut it off. Restart it, let it warm up however much you are used to (or no warm up at all, doesn't matter once you've started and stopped it) and head down the road. Because you shut it off and restarted it before you started down the road, the computer doesn't realize that you had your car plugged in when you "shouldn't have" according to GM's thinking.

Let's say you park your car more than 10 hours, it's -12 and you plug your car in over night with the new regular cord end . If you just start the car and head down the road, once you've driven more than 400 seconds at over 15 mph, you will run into trouble. If you cycle the key before you leave home, that fools the computer and removes the 10 hour rule and the computer thinks the car was driven less than 10 hours ago, and that is why the engine coolant was warm.

And please don't ask me what genius figured out that we are not smart enough to plug our cars in at the right temperature and that he was smarter than us....

Rant over. I did our daughter's car about 3 weeks ago and it's worked fine following the above method. I just cut the silly end off our G8 now too.

I may have posted this last year but wanted to do it again since parts of the prairies and NW Ontario are pretty chilly right now.





-- Edited by 4SPEED427 on Saturday 11th of January 2025 06:17:31 PM

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65 SD L79


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hope they don't use the same -18 plug for the diesels



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4SPEED427


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Yup, 'fraid so, same end on the Duramax's.

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1966 Strato Chief 2 door, 427 4 speed, 45,000 original miles 

1966 Grande Parisienne, 396 1 of 23 factory air cars (now converted to a "factory" 4 speed)
427carl


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wow ...  thats cool....



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Canadian Poncho


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I have never heard of these temp sensitive block heaters. Learn somthin' new every day!

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GrtDanes


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I just buy an inline heater .never had a problem.


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4SPEED427


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But you can't even do that. It's not the heater that messes up the computer. It's the fact that the key was off more than 10 hours, then you started your vehicle and drove more than 400 seconds over 15 mph when the coolant was warm on startup but the outside temp was not below -18. It wouldn't matter who's heater you used to heat the coolant, the ECM says you can't do that.

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1966 Strato Chief 2 door, 427 4 speed, 45,000 original miles 

1966 Grande Parisienne, 396 1 of 23 factory air cars (now converted to a "factory" 4 speed)
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427carl


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Carl Stevenson wrote:

But you can't even do that. It's not the heater that messes up the computer. It's the fact that the key was off more than 10 hours, then you started your vehicle and drove more than 400 seconds over 15 mph when the coolant was warm on startup but the outside temp was not below -18. It wouldn't matter who's heater you used to heat the coolant, the ECM says you can't do that.

         wow      and since we are learning "stuff"   I always wondered about a extension cord for block heaters    What are they about?   

 



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norontcan


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If Carl wasn't such a straight shooter I'd almost think he was pulling everyone's leg with this.
Amazing what the manufacturers can come up with. Can you order a vehicle block heater delete?
My Escalade has options galore but not heated mirrors which I could actually use.

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4SPEED427


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I'm afraid you are right Ted, it's so far fetched it's hard to imagine.

I was able to figure out how to defeat this stupid thing by googling "gm block heater cord" and wasting a couple of hours reading and reading until I finally got it sorted out in my head. I tried to simplify the explanation on how to defeat it the best I could.

It's supposed to be -26 here tonight so technically I won't even have to cycle the key on my car before I go to work tomorrow morning because it's colder than -18, but I just want to develop the habit of doing it any time it was plugged in. That way I don't have to check the morning outdoor temperature each day to see if I am plugged in "legally" or not.

I don't normally use terms like bull**** but that's what I think this stupid setup is.



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1966 Strato Chief 2 door, 427 4 speed, 45,000 original miles 

1966 Grande Parisienne, 396 1 of 23 factory air cars (now converted to a "factory" 4 speed)
koolconvertible


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can someone post a picture of what you are talking about including the ends? Being in Oz never seen one and am curious!



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cutting a roof off a four door is NOT a convertible.....

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427carl


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koolconvertible wrote:

can someone post a picture of what you are talking about including the ends? Being in Oz never seen one and am curious!

 download.jpeg

You remove a "front plug" from the side and bolt this in......



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4SPEED427


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This is what WAS on the end of my Holden, er......, I mean G8 block heater cord.

Behind that round black disc is a temp sensitive gizmo that only completes the circuit below -18C.

DSCF0984.JPG

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1966 Strato Chief 2 door, 427 4 speed, 45,000 original miles 

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mr409


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Thanks very much for this tip! My mom and dad have a MINT 2007 Impala SS with 61,000 KMS. It did this last winter (cause I cut off the end and replaced it-since got a free proper cord from a buddy at an auto wrecker) and this winter once so far and it has the proper cord end on it! My "fix" was to put it in the warm garage overnight and then it was fine, but Carl's tip is way better! It will be sold this spring to buy a Toyota or Honda. What a stupid problem! I guess they want the GM piston slap to get worse and worse-that 5.3 just clatters away especially cold and unfortunately its not due to forged pistons and a mechanical camshaft! If it's minus 10 I plug my cars and old truck in every night all night and they stay plugged in all day at work in the winter. New GM cars are CRAP. My 86 GMC 4x4 is new enough!!! How in the world does a Duramax start "not plugged in" unless colder than minus 18!

 



-- Edited by mr409 on Tuesday 19th of January 2016 12:04:01 AM



-- Edited by mr409 on Tuesday 19th of January 2016 12:05:36 AM



-- Edited by mr409 on Tuesday 19th of January 2016 12:07:03 AM

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4SPEED427


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I'm glad it was some help Adam. It irks me every day that they have done this because I encounter it pretty much every day at work these days when it's so cold. I typically plug in once we get to about -12 or -13, I can't stand starting engines that aren't plugged in when it's colder than -15. Also, almost every day at work these days I get the "Why would I plug in, it still starts at -25?" from customers. Some people don't understand the concept of taking care of a vehicle.

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koolconvertible


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is it possible to buy a different thermocouple and controller to make up a "magic" box?



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cutting a roof off a four door is NOT a convertible.....

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Pontiacanada


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I have a block heater in my 2006 GMC truck (regular 3 prong plug) ... I've never used it.

Instead of cutting the cord and putting a new regular three pronged plug on it, could you not get a old style regular male plug and the whole cord (with the female block plug end), and plug it in at the block heater? More water tight.



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4SPEED427


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I know this is an old thread but we're coming in to that time of year again so I thought I'd bump this up in case anyone is not aware there is a way around this stupid feature (which I now see showing up on other brands besides GM)

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hawkeye5766


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Carl Stevenson wrote:

I know this is an old thread but we're coming in to that time of year again so I thought I'd bump this up in case anyone is not aware there is a way around this stupid feature (which I now see showing up on other brands besides GM)

 Thank god Carl showed a pic....you guys had me lost!biggrin



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cdnpont


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Why would it have even mattered to GM if you wanted to use the block heater even in the middle of the summer? 

What harm would it have done? Was it a fire risk at higher temperatures?



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68 Grande


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My first vehicle with one of these cords was 2006 Cadillac SRX. I was quite upset about this temp sensing cord end and I was going to cut it off and replace with a regular male end because I could not accept that this system would not somehow cause harm to starting a cold engine. Well, the service writer at the Cady dealer gave me an earful of how some old guy couldn't understand this type of plug and cut the end off and replaced with a regular male end, plugged it in, started the car up and the computer went haywire.

Needless to say, I think we have had three other vehicles since the SRX including Fords and GM's with these plugs, driven by all our family members and the Fords are the same thing btw as the GM's, they don't come on until -18 or something like that. I don't think about it anymore. I plug it in and if it is 18 and colder great and if it is warmer than minus 18, then I let the vehicle warm up a bit. Whatever.

Its funny because I have heard people tell me that they plug their "new" car in while parked overnite in their garage. I asked, what is the temperature in your garage and the answer is about minus 5. Well guess what I say, your car is not plugged in because your temp sensing cord doesn't kick in until its -18. Plus, if your car is sitting in a garage - 5, you don't need to plug the frickin thing.

It doesn't bother me anymore, never had any issues so I just accepted it.

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4SPEED427


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Well, the nice thing is, if you are willing to stop and restart your car once in the morning if it's warmer than -18C, you can defeat this whole stupid system. My blood pressure goes up when they do crap like this!

I've been doing this almost 3 years now without a hiccup and I can plug my car in at work when it's -15C. My threshold is typically between -12C to -15C for plugging in. I don't like listening to cold pistons rattle, which the 6.0 litres (like our G8) are famous for.

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65Camino


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Curious what was the logic for it in the first place? Why even have it if the temp never goes that low? Does it shut off if the temp gets warmer then -18 overnight ?

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4SPEED427


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Yes, it only makes a connection in the cord if the temp is roughly -18C or colder.



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1966 Strato Chief 2 door, 427 4 speed, 45,000 original miles 

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aeronlearmonth


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Hey,

This was a really great write up. I am going to try this to my 2008 1500 with the 5.3L this weekend. 

Do you have to completely start and turn off the truck, restart then drive? Or does simply rolling the key to on then off, then start it and drive away? Or does this not trick the computer enough? 

 

Thanks!

Aeron 



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