Unleashed my Chevy block heater (redneck re-engineering)

[DonR]

I heard it started in 2005. It is "all" cars. I bought a heater for the wifes hot rod & it has the stupid cord on it. I have not installed it yet.

On the 10 hour rule, do you know if the vehicle needs to be running or just have the ignition turned on?

Don

[Fubeca]

From the linked thread above:

Conditions for Running the DTC

• The ignition is ON.

• DTCs P0112, P0113, P0116, P0117, P0118, P0128, P0502, P0503 are not set.

• The start-up IAT is more than -7°C (+20°F).

• The vehicle has a minimum ignition OFF time of 10 hours.

• DTC P0116 runs once per drive cycle when the above conditions are met.


Conditions for Setting the DTC

• The start-up ECT is more than the start-up IAT by 100°C (180°F). OR

• The start-up ECT is more than the start-up IAT by 15°C (27°F), then the vehicle must be driven for more than 400 seconds over 24 km/h (15 mph). If the IAT sensor temperature decreases more than 8°C (14°F), a block heater is detected and the test is aborted. If the IAT sensor temperature does not decrease, a block heater was not detected and DTC P0116 sets.


Action Taken When the DTC Sets

The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.

The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.


Conditions for Clearing the MIL/DTC

• The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.

• A current DTC, Last Test Failed, clears when the diagnostic runs and passes.

• A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.

• Clear the MIL and the DTC with a scan tool.

I don't know if this applies to all GMs or just the trucks.

[inglewood3]

Fubeca - I was researching the block heater issue today and saw your old posts. I have the same issue with my 2007 Tahoe. Can you give me some more detail on how to modify the plug to get it to work?

Thanks.

[Fubeca]

On my plug there was a little 'wart' on the top of the plug. I used a screwdriver to work the cap off of that and pulled the thermostat out, then used something (I don't remember what) to short the contacts in there and put the cap back on.

Sorry - my memory is a little vague - I've slept since then

[inglewood3]

Same deal here, exactly as described. I did talk to the manufacturer, they claim the software issues as well and apologized for GM's issue. How does the heater do? Still working? On the DTC code, at what point is it best to clear it?

[Fubeca]

I've since moved to Texas and very rarely use the heater - can't speak to it's longevity. I've never had a trouble code from it - because my situation wouldn't have triggered the code. I also have code readers and wasn't worried about resetting it if it triggered.

[inglewood3]

It is likely I will meet those conditions here. How long did you use it with the mod? Zerostart sent me a technical bulletin from GM on the issue. Too bad they still haven't made the software change. The 2011 models are the same.

[Fubeca]

Maybe 10 times - if that. I figured I could easily replace the cord if it became a problem.

[inglewood3]

I will give it a good test here starting tonight. The best one ever was on my Tucson, you could leave it on for days without any issue. Thanks for the help. Take care.

[JasonG]

If you wanted to ensure no trouble codes you could wire in two timers.
First one runs for 8-9 hours then trips the second to turn on the ign for a min.
The 10hr logic trip would never occur.

Never have any issue with the block heater in my '94. What's a MIL? Must mean you have one of them computer thingys ?