Bypassing Block Heater Sensor

00Silverado4x4 · January 9, 2012

I doubt it. Unfortunately even if there is a way to "adjust" would still mean cutting into the end. Even when I was in Alaska I didn't use mine & had no problems with starting. I'd be more interested in a battery warmer to save it from freezing so much.

tbhuge · January 9, 2012

I've got the diehard platinum battery that's made by Odyssey. I normally just park in the garage, however I have been redoing the bathroom in my house and have the garage being used with tools and new stuff to go into the bathroom. So I have been parking the truck outside for the last month or so. I just noticed that I can't really even tell that the block heater is even plug in, because it still starts like it is really cold and has to warm up for a while.

Oh and I am up in Alaska. Thankfully I am Anchorage though and not Fairbanks!!! They saw -40 and -50 in the last week!!!

AlaskanSilverado07 · January 10, 2012

I was recently transferred by my employer from Anchorage to Houston, and lived in Alaska since 1966. I've owned several Silverados including a 2007 and 2009 which both had the "new and improved plug" which turns on at zero degrees. The thermostat won't allow the voltage to pass until it is below zero degrees. On my 2007, I decided to cut off the plug and install a new one. It started throwing codes and I ended up splicing the old one back on.

The amazing thing is in Anchorage they've had a program for years called "Plug in At 20" where the Municipality wants you to plug in your car below 20 degrees as it helps improve the air quality. I called the Muni to explain their program was a joke when it came to the Chevrolet's and they were astounded to learn it. Needless to say, they didn't discontinue the program and never mentioned this about the GM vehicles either.

I grew up in Fairbanks where the plug would have worked great but in Anchorage and warmer climates it's useless unless it drops below zero. ANd yes, it does a great job at -10 or -20.

ditchpickle · January 10, 2012

I found that if I run synthetic oil in my 07 classic 6.0 liter, It starts easily, without any funny noises, even at -30C. I have never once plugged it in.

motoGPatrick · January 10, 2012

http://www.espar.com/html/products/technology_coolant.html

I have seen these in action on trucks in severe climates. They make them for diesel and gas. Splice it into your coolant system and it sips and burns a little fuel to keep things warm...

I think I did things the smart way.. I just moved from MN to So-cal.. No cold wx, no rust and it is always sunny.

bbb · January 11, 2012

has anyone tried an oil pan heater that warms the oil instead of the coolant...might work?

tbhuge · January 11, 2012

That Espar set up is interesting, however not very cost effective. There has got to be a low buck option. If the entire sensor and circuitry for when the block heater kicks in is in the plug, what circuitry is in there?? There is only so much room in that plug. I'm not an electronics expert, but there has to be a way to duplicate it but change it slightly so that it turns on at a different temperature.

RockySierra · January 11, 2012

I don't think this is a traditional block heater anymore and more of a coolant bottle heater now? Not sure

CheapCharlie · January 11, 2012

FWIT. I replaced the end of my "tumor/thermostat" equiped block heater cord with a standard male 3 prong end. Now, when the temperature is above the preset 0C/30F with the heater plugged in, I get a fault message after start up. The message is "ENGINE HOT A/C TURNED OFF". In addition, the temperature gauge stays on zero and the engine fan runs continuously. I am able to get heat, lots of it!!! I have successfully cleared the fault message and other symptoms by disconnecting the battery, waiting about two minutes and re-connecting it. Everything works as it should thereafter. But that's a pain to do every day and the check engine light will come on if it has the same fault code registered twice within 40 days.
It has to do with the rate of temperature increase sensed by the "computer". With warm coolant, and therefore warm thermostat, there is no rise in engine temperature during the warm up phase of engine operation. This "anomaly" triggers various systems to shut down and protect the engine (fan, temp gauge etc.). I believe it has to do with emmisions as well. Standards imposed by the EPA as previously mentioned in this and other threads.

All that to say that it looks like I will be re-installing the original plug end and living with cold starts when it's around 0C/30F

Mike

A couple years ago I cut off the cord end & installed one from the hardware store & the same thing happened. $150 to install a new thermostatic controled block heater cord where it kicks in at -18C "ambient temp". What GM and/or the EPA dosn't understand is windchill. Last weekend in central Alberta we had -34C ambient with -41C windchill. We have many days where the ambient temp can be -10C to -15C ambient with windchill temps well below -20C, in these conditions no electricity will get to the block heater. On these days my truck will make an awfull grinding type noise on start up and lasts a couple seconds, I've discussed this with the dealer and they have no idea what it is.

Still looking for a fix!

I live in a very cold climate as well and i'll tell you that windchill does not affect anything that is metal. It only affects us and our skin. Wind chill is the temperature "felt" on exposed human skin.

dewfpo · January 11, 2012

That Espar set up is interesting, however not very cost effective. There has got to be a low buck option. If the entire sensor and circuitry for when the block heater kicks in is in the plug, what circuitry is in there?? There is only so much room in that plug. I'm not an electronics expert, but there has to be a way to duplicate it but change it slightly so that it turns on at a different temperature.

The sensor in the plug is a simple bi-metallic piece of metal that makes contact at about 0F. You can cut the rubber on the 'blister' back and stick a metal washer in there so that there is always contact and it will come on whenever you plug it in. But.... if you have it plugged in when it's 'warm' out (say 30F or warmer) you run the risk of tripping the instrument panel MIL on cold starts giving you a message that the coolant temp sensor is out of spec.

You can also just go to NAPA and buy a regular block heater replacement cord without the built in thermostat.

I've done both and either works fine.

I've been plugging mine is on really cold days since 2004 and haven't had a code thrown yet.

DEWFPO

tbhuge · January 15, 2012

That Espar set up is interesting, however not very cost effective. There has got to be a low buck option. If the entire sensor and circuitry for when the block heater kicks in is in the plug, what circuitry is in there?? There is only so much room in that plug. I'm not an electronics expert, but there has to be a way to duplicate it but change it slightly so that it turns on at a different temperature.

The sensor in the plug is a simple bi-metallic piece of metal that makes contact at about 0F. You can cut the rubber on the 'blister' back and stick a metal washer in there so that there is always contact and it will come on whenever you plug it in. But.... if you have it plugged in when it's 'warm' out (say 30F or warmer) you run the risk of tripping the instrument panel MIL on cold starts giving you a message that the coolant temp sensor is out of spec.

You can also just go to NAPA and buy a regular block heater replacement cord without the built in thermostat.

I've done both and either works fine.

I've been plugging mine is on really cold days since 2004 and haven't had a code thrown yet.

DEWFPO

I'm not familiar at all with the bi metallic piece of metal, so if it is just a simple piece, is there a way to make or buy just one of these that engages at different temperatures than 0 degrees and then add it to a new plug. I would like to shoot for 20-25 degrees. Any electrical engineers out there??

Cruze Diesel · September 11, 2013

This is NOT an EPA issue. No other manufacturer does this with their block heaters, only GM. The EPA doesn't mandate this. GM chose to wire up their sensors this way to save $$$, and to ensure their engines will start. Yes, a partially warmed engine won't start the way they have their sensors set up. Dumb if you ask me.

Bertminator · January 12, 2017

has anyone tried an oil pan heater that warms the oil instead of the coolant...might work?

My Best friend did this and he says it works great. To my knowledge, he has NOT had any trouble codes. I may do the same on my truck for next winter. In "Winterpeg" It gets BRUTALLY cold (just like tonight -25°C and that's -38° C with windchill)

bbwb · January 12, 2017

I seem to recall, this was discussed long ago, and the conclusion was that GM put the thermostat on the block heater as without it, codes would be set. So to make sure the sensor temps would be below the threshold, they installed the thermostat.

Also, for those that are wondering if the heater is working, go to the wall receptacle and pull the extension cord out (may have to do this several times) but look for a spark. If you get a spark, you are drawing current

foggydog · March 7, 2019

I replaced my heater cord end with a normal end and now when I use it in warmer temps the computer sees the engine is warmer than what it should be compared to ambient and brings up the code "engine hot AC off" which also shuts off the engine temp gage to prevent damage. resets once engine is cooled down. have trouble restarting truck immediately after because I think it sees no temp now and "chokes" the engine . will restart once engine cools down some