Unleashed my Chevy block heater (redneck re-engineering)

[Fubeca]

Well,

It seems GM couldn't figure out how to get their trucks to pass the OBDII mandatory sensor tests if a block heater is used, so intead of fixing the programming, they hobbled the block heater.

They installed a thermostatically controlled block heater that only works at temperatures below 0*F

There are plenty of cold days that I'd like to use the heater, but it won't work because it isn't cold enough.

So I yanked the plug apart and broke the thermostat out and shorted it's contacts so the heater always thinks it is below 0*

Now I'll have to do some testing to see what difference it makes

[DonR]

Be prepared to see a CEL code relating to the coolant temperature sensor being faulty.

Apparently the computer cross checks several temp. sensors & Doesn't like it when one is warmer.

I probably would have tried to get a non-thermostatic cord because the cord you just ruined will cost $67 to replace. The regular ones are about $26.

Let us know how it goes.

Don

[MetroMPG]

Don - I have a feeling he's smart enough to "un-ruin" the cord he just modified, should he need to.

What I'm curious about is why the vehicle was set up with a crippled heater in the first place. That's the first time I've heard of such a thing.

[Fubeca]

The cord can't be un-ruined, it is permanent.

There is a very specific ruleset that has to be met for the code to happen. With my driving situation, I don't think I'll meet that criteria ever. If I do, I have a scanguage and another computer that can reset the code. I knew the risks going in

Explanation of Rationality Check
The P0116 diagnostic (engine coolant temperature sensor rationality check) can fail if the indicated coolant temperature is too high at engine startup, after an extended time sitting without the engine running.

After a vehicle has been parked for a number of hours, the engine coolant temperature is typically very close to ambient air temperature. This is the definition of a cold start. After startup, OBD regulations require that the PCM look at the rate at which the coolant temperature sensor heats up, from a certain starting point. If the coolant temperature sensor does not heat up according to expectations, a DTC P0116 will set.

More here: http://www.gm-trucks.com/forums/inde...pic=47527&st=0

It has to be sitting for more than 10 hours without a start, and the IAT must meet certain criteria.

I will not be replacing the cord with a new factory cord. If this plug fails, I'll chop it off and put on a new non-thermostatically controlled plug from the hardware store. My local dealer looked and could not find a non-thermostatically controlled cord listed for a 2006 silverado.

My theory on why it was set up this way is that GM didn't want to take the time to engineer a software solution that would recognize that the block heater was on rather than a sensor issue. I'm very frustrated that I have a block heater that is only designed to work below 0*F.

It definitely helped this morning. Now to see how much energy is expended to warm up the engine with the block heater.

[MetroMPG]

Thanks for the explanation. I agree: they dropped the ball.

[Frank Lee]

Wow, that's the dumbest thing ever. Well, it isn't, but still.

[gone-ot]

Originally Posted by Frank Lee

Wow, that's the dumbest thing ever. Well, it isn't, but still.

"...may the best car win!"

[luvit]

i read somewhere around here that a user uses his block heater all year until he see ambient temps of 90F.
is that even measurable on wear or FE?

[Neddy Seagoon]

Funny this should come up, I have a 09 Vibe with a block heater which died after two winters, I have it set for 2 hours before heading off the work. I know it died due to my Scangauge reading ambient temp instead of 30c which is normal when starting.
As you know a Vibe is a Toyota built car, but the dealership tried to fob me off the warranty repair by telling me the block heater does not work until -18c? I told them it was shorted and worked fine up to that point and told them the reading on my Scangauge, their reply was what's a Scangauge?
Anyway it's been replaced and works fine now, but there must be something in this block heater temp thing with them to say that.
By the way my old 03 GMC has a block heater ( which only exploded once under warranty, no joke ) and that works all the time, it must be a recent GM problem.

Neddy Seagoon.

[Fubeca]

I don't know if it applies to all GM products or just the trucks. I believe they started in 2004 with this style of block heater cord.