E67 and VSS - Removal of the TCM for manual transmission

[S10Wildside]

I'm working with a 2008 Trailblazer SS E67 and want to use ECM C3 pin 66 and C3 pin 67 for VSS high and VSS low because of a manual transmission application. While this looks good on paper, I'm not seeing a VSS signal in the scan tool.

Has anyone eliminated the T42 (which has a VSS output to ECM C3 66), used a manual transmission, and a VSS signal directly to the ECM?

This is not yet installed in a vehicle, but being tested on the bench.

[S10Wildside]

I added the TCM to the bench and the VSS works fine. I'd like to avoid the TCM if at all possible.

[GMPX]

Maybe using an 07 CTS-V calibration would be a better option?

[S10Wildside]

Maybe using an 07 CTS-V calibration would be a better option?

I agree! The only catch is that the project requirements include cruise control...which locks me into the Trailblazer SS E67 ECM.

[alan91z28]

Do you have the parameters
- Vehicle Speed Output = RepTOS
- Wheel Speed Output = Enabled
- Speed Limiter Source = Calibration

The pins are the right ones

The first two parameters are what i needed to change to get the GMPP E67 controller to work along with writing the entire file versus just the cal several years ago

thanks
alan

[S10Wildside]

Thanks Alan.

Are these EFILive parameters or HP Tuners. I cannot find these in the EFILive E67 ECM calibration.

*EDIT* I don't see these in HP Tuners either. Maybe this is specific to the GMPP calibration?

[Taz]

- Vehicle Speed Output = RepTOS
- Wheel Speed Output = Enabled
- Speed Limiter Source = Calibration




Those settings are used by default in a Trailblazer calibration ... no worries if you can't access them.


Regards,
Taz

[S10Wildside]

Thanks Taz.

I can also tell you that without the TCM, SAE.VSS always displays 158 mph. I disabled U0101 (Lost Communication With TCM) with no effect on VSS.

[alan91z28]

yes you're are right Taz i just looked in a reference file for the trailblazer and those are indeed set that way

mike, i am not sure where these are in EFI Live, in HP they are under the speedo tab and they are set like i referenced on the trailblazer when i just looked

the other thing i noticed is that there are a couple of weird DTCs that might give you some trouble... try turning off p608 and see if that helps

what do you see the vss ppm out signal C1 39?

right now in my 85 IROC with the LS3 type and TVS2300 i am running the GMPP ECM
- GMPP E67 ECM Part Number 19258268 (pre-loaded with GMPP OS 12638778)
- GMPP OS 12638778 baseline
- heavily modified of course, but this is a great OS to start as great MAF range and Fuel (up to 16 g/s injectors)

i am not sure if they have made these OS available over their web interface yet... it would be great if you could just load up an e67 with it

[ScarabEpic22]

What are you using to input a VSS into the ECM? Its going to read a funky value unless you feed it a proper signal, start with that and adjust the speedo params if necessary.

Ive looked into this a bit when one of the TBSS guys was trying to swap a T56 into his TBSS. He scrapped the project, but Im pretty sure you can run the stock OS and kill the related codes for the TCM.

Can you post the base file you're working with? And what kind of vehicle is this going in, sounds like a swap (just curious!).

[S10Wildside]

I'm using a VSS from a T56 transmission and spinning a reluctor on the bench top. The 158 mph value is odd because it is displayed with VSS connected and without TCM connected. Once the TCM is connected SAE.VSS goes to 0 and properly reads VSS.

Calibration at http://www.eficonnection.com/temp/Smokeys_2008TrailblazerSS_0002.tun. (EDIT - So that's odd. You cannot download this file. How do I post the file?)

The conversion is an LS3 going into an early (80s?) BMW.

[S10Wildside]

what do you see the vss ppm out signal C1 39?
I'm curious about this as well, but don't have an instrument cluster on the bench to know.

[alan91z28]

I'm curious about this as well, but don't have an instrument cluster on the bench to know.

do you have an oscilloscope or fluke frequency capable meter that you could look at the signal? i use this E67 output to a cable-x box in my iroc to drive the mechanical speedo

[S10Wildside]

do you have an oscilloscope or fluke frequency capable meter that you could look at the signal? i use this E67 output to a cable-x box in my iroc to drive the mechanical speedo
I do. Not sure if I'll have a chance to bench test that this week.

[schwoch1]

Anybody come up with anything on this yet?

Mike

[S10Wildside]

No, nothing. The harness, ECM, and TCM have been delivered and will soon be installed. My customer requested to proceed with the TCM. If he runs into any problems related to VSS or TCM without automatic transmission, he will rework the harness to add the VSS to the ECM and move forward from there.