CASE Learn procedure for a GTM in HPtuners

[rev2xs]

Hey guys,

My battery died over the weekend and needs to be replaced, no biggy. But what is a royal PITA is the fact that my PCM is now throwing out DTC's P1336(Crankshaft Position (CKP) System Variation Not Learned (SES) and P0300(engine misfire detected) error codes which mean that the Crank sensor value needs to be "relearned". These two errors go hand in hand and mostly occur together because the PCM no longer knows how to time the spark properly because the crank sensor isnt calibrated anymore. Apparently, this can happen if your battery is pretty weak and the PCM can "forget" the value it has stored. It also occurs with an engine rebuild and a PCM replacement. This "relearn" procedure in a stock Corvette is a piece of cake.

In a GTM however, its a problem because the process to activate the calibration feature in HPtuners (or any tuning program for that matter) is not possible in a GTM unless you have the brake light switch wired into the PCM so that it knows you are pressing the brake. Oh, and the PCM has to know if the auto gearbox is in park or your manual is in neutral too. Without this info, it wont allow you to start the CASE learn process. So, what the heck can we do if this happens to us GTM builders Without the need for rewiring to fool the PCM? Or any other custom car builders who use an LS engine? I read somewhere online that in HPtuners, you can bypass these requirements but of course, conveniently, this post doesnt say how. Nor does the help file in HPtuners or the HPtuners forum. Has anyone had to do this in their GTM? Perhaps when they worked their engines and upgraded them? As i said, its a simple thing to get rid of providing your wiring is as Chevy intended in a Corvette.

Thanks, Tom!

[LCD Gauges]

Tom,


I'm not aware of the inputs you describe in order to allow a case learn...but then, this would be my first GTM! You can always use a 50 ohm resistor tied to ground, or VCC
to the respective PCM trigger to fool the computer.

As for case learn, HP TUners has menus to select transmission type, and other options to get the engine fired. Selecting VATS off, is another key feature to getting
many of the security issues to free-up.

Check out these menus, and let me know if they help.

These are found in the VCM Scanner:
GTM_VCM_options.jpgGTM_case.jpg
This is found in the VCM Editor:
GTM_auto_man.jpg

[rev2xs]

Thanks for the reply

Ok, after doing a lot of research on the matter through various LS1 and Vette forums, this is what others had done in order to get access to the CASE learn procedure in HPtuners.

Now, this is for a stock Corvette LS1 from early 2003 so the pinouts maybe different for earlier year models. And also, this is for a PCM which originated from a car that had an Auto trans axle.

1) I wired pins 34(white) and 72(Yellow) on the blue PCM connector together and earthed them. This will make the PCM think that the car is in Park.

2) I then wired a switchable 12V power source through a 10a fuse and a 12v light bulb to pin 33 on the Blue connector of the PCM which is a purple wire. This is the TCCBrake switch signal input. This way, you can switch on the bulb and make the PCM think that the brake pedal has been applied.

3) I flashed the PCM through HPtuners and set the "PNRDL Equipped" setting to "PN Only".

This will give you access to the CASE learn procedure in HPtuners should you need to run it in a GTM.

However, even though i now do have access to CASE learn, i'm getting a strange issue that when i try to run the procedure, i get an error saying that the "Vehicle is moving" and it wont let me complete the process. PITA basically. I'll keep you all updated on what can be done.

[VD2021]

Tom,
This may or may not be the issue, but your VSS may be vibrating. You could remove it from it's bracket and try the procedure to see if this is the case.

[rev2xs]

Thanks Vidal, i was actually thinking along those lines and did exactly that. The error went away which was good, however, it was replaced by another error, "RPM too high" this time. Went back to the HPtuners forums and as it turns out, there is a setting in the PCM for the "Park/Neutral" RPM limit. That is set to 6200rpm. There's the problem. The test needs to go to a maximum of 4000rpm and have the fuel cut out kick in and thats when you back off the gas pedal. So what i had to do is change this setting under the "Engine", "Fuel control", Fuel cutout" sections of the VCM editor in HPtuners. Changed the "P/N" values to 4000rpm and this seems to have worked. Problem seems to be solved, i hope...