E67 GMPP 480hp LS3 to communicate with T42 auto

[Tapi]

Hi.

I have here a GMPP LS3 in '60 Impala which had the EZ-TCU transmission controller. I wasn't happy with the aftermarket transmission controller, so I bought a T42 transmission controller and made a wiring harness to it. I copied the harness layout from GM service manual as it is in 2008 Trailblazer SS which was (to my understanding) with E67 and T42 from factory.

Now I finished with wiring the car. My plan is to have my friend with Tech2 to write the E67 and T42 over with a stock tune from Trailblazer '08. After that I would start normal tuning in hopes the car would no longer have the idle air limitations of GMPP tune and a chance to tune the transmission with HPtuners.

Its not yet written as Trailblazer but I thought I would connect the HPtuners and read if I possibly see the transmission controller there already. I didn't.
The connection failed few times when I started reading the tune (E67 GMPP was recognized) and one time it announced "unknown controllers detected".

Does this mean I'm on the right track or have I messed up something? Is the Tech2 still able to write the tune over even when the present situation shows there is interference with these 2 modules?

To my understanding the only thing affecting the communication is the data communication between ECM (X3 pin 33 to TCM pin 37 / X3 pin 53 to TCM pin 38). This I did by splicing the wires from ECM to TCM and the only other destination for the wires must be the OBD plug. I haven't put a 120 ohm resistor to wires from TCM which would go to BCM if this car had one.

[Shrek]

You are about to step into a deep hole ... time to stop and think things through.

I would highly recommend that you do NOT overwrite the CPP (GMPP) E67 ECM - as there is no way to put back the CPP (GMPP) programming, if it became necessary.

Your crate LS3 engine will have a 2009+ "car" throttle body (gold blade), and the CPP (GMPP) kit will have used a CTS-V accelerator pedal (APP). Neither this throttle body, nor this APP, are compatible with a TBSS calibration.

[cadillactech]

CAN bus needs two 120 ohm terminating resistors. One is already in the ECM. You will need another one in there for the modules to talk to each other.

[Tapi]

Thank you, the warning came in time.
I didn't realize the TBSS calibration wouldn't work with T/B and the pedal.
There isn't a calibration which would work then?
How would you solve this problem?

[Shrek]

CAN bus needs two 120 ohm terminating resistors. One is already in the ECM. You will need another one in there for the modules to talk to each other.

No need to add any resistors on the CanBus network with an LS conversion project.

[cadillactech]

No need to add any resistors on the CanBus network with an LS conversion project.

You are right, TCM has a resistor too. Carry on!

[Shrek]

Thank you, the warning came in time.
I didn't realize the TBSS calibration wouldn't work with T/B and the pedal.
There isn't a calibration which would work then?
How would you solve this problem?

As long as all of the Electronic Throttle Control components are properly matched, you can program the ECM and TCM anyway that you need.

If a TBSS calibration is what you would like (this also gets you ECM operated Cruise Control), then you would need to change the throttle body, and the APP (pedal) to match (i.e. TBSS items).

There is no production E67 ECM calibration that will work with throttle body and APP that you currently have in place.

[blindsquirrel]

You are right, TCM has a resistor too. Carry on!

It does, but it's not internally connected to anything like in the ECM. You have to jumper TCM 6/7 over to 15/19 to use it.

screenshot.04-10-2021 18.31.48.png

[cadillactech]

It does, but it's not internally connected to anything like in the ECM. You have to jumper TCM 6/7 over to 15/19 to use it.

screenshot.04-10-2021 18.31.48.png

Yup GM and their many different CAN bus wiring configurations.

[K-fed]

I was in the same boat as you with the GMPP e67 ECU and the EZ-TCU controller. Didn?t like the transmission controller so I just purchased the GMPP transmission controller for my 4l80e. It did need some slight tweaking in the calibration but it works great and is plug-n-play.

[cadillactech]

I was in the same boat as you with the GMPP e67 ECU and the EZ-TCU controller. Didn?t like the transmission controller so I just purchased the GMPP transmission controller for my 4l80e. It did need some slight tweaking in the calibration but it works great and is plug-n-play.

Is that controller a just a T42? Sounds like you were able to modify it with HP tuners?

[Shrek]

Is that controller a just a T42? Sounds like you were able to modify it with HP tuners?

The CPP (GMPP) 4-speed transmission controller is a PCS product. It looks similar to a T42, but with the 49 pin connector rotated 90 degrees.

It uses proprietary software, and does not interface via the OBD-II connector. They come with a 3-pin wiring harness interface connector, with a USB on the other end (to connect to a Notebook computer).

Proprietary TCM tuning software is provided by GM with your kit purchase.

[cadillactech]

The CPP (GMPP) 4-speed transmission controller is a PCS product. It looks similar to a T42, but with the 49 pin connector rotated 90 degrees.

It uses proprietary software, and does not interface via the OBD-II connector. They come with a 3-pin wiring harness interface connector, with a USB on the other end (to connect to a Notebook computer).

Proprietary TCM tuning software is provided by GM with your kit purchase.

Thank you.

Out of curiosity, do you know if the GM T42 and the PCS controller are related at all? Made by the same manufacturer?

[Tapi]

Thank you all for the valuable info this far. I bought a set of TBSS T/B, E67 ECM and now I'm trying to source a pedal for the same car. In fact when I removed the T/B I found out it's a LS2 throttle body and not the infamous golden one.
So it seems I will replace only the ECM and the pedal to achieve the "normal way of tuning".

[Tapi]

Now I received a replacement ECM. It seems to be from 2007 GMC Envoy 5.3 Denali.
I also received the throttle pedal, part number 15145758.

I put the ECM into the car, as well as the throttle pedal.

I connected the Hptuners and tried "read entire". First it announced "unknown controllers found". After that read failed.
I disconnected T42 from harness and read again, then of course the read entire worked.
I logged the parameters just to see how the pedal worked: From 0 to 50% pedal position it showed rising 0%->47% and from 50 to 100% position it showed 47%->0%. Then I tested with the original GMPP pedal and it showed 0% until from the middle of travel it raised to 32% towards the end. So it seems this pedal is not a direct fit with this ECM and/or the LS2 T/B.

I still have one T42 in the mail which should be the original pair for this specific E67 ECM. The one Itried was from another car.
Does it look like my read problem is due to E67 and T42 not being a pair originally or should I look for error in my connections?

[Shrek]

The CPP (GMPP) wiring harness that you have, is setup for a CTS-V APP (pedal). The APP connector is the same for the CTS-V and the TBSS, however the pinouts at the APP connector are different for the TBSS APP. Also, you must use a Gen 4 Truck style throttle body. The Car style throttle body that you have will not work with a TBSS APP and programming.

That is your first issue.

The second issue is the CanBus wiring. The original CPP wiring harness had the CanBus wires running from the E67 ECM to the OBD-II (DLC) Port. The PCS TCM (that looks similar to a T42 TCM) does not use CanBus communications.

Also, the wiring (pin arrangement) to the PCS TCM is different than an OEM production T42 TCM. This (the pinouts) will need to be configured as necessary.

[Tapi]

Thanks. The second problem has been solved now. A skilled friend looked at my schema for the serial data connection between modules. He pointed out what I have missed: serial means the modules need to be one after another and I cant put one in line parallel. I changed the wiring so that from obd-plug the data goes to T42 and from there to E67. This works and I could read both ECM and TCM tunes!

Tomorrow I will look into pedal wiring differences.

[Tapi]

Now it runs again! At least on my lift it does

The good: I can finally tune the idle in traditional manner and the T/B does not stay >20% open and the ignition advance controls the idle together with reasonable throttle opening.

The bad: Vehicle speed in scanner raises to ~10mph on drive when I release the brake but it decreases to ~2 mph while accelererating. The speedo stays on 0 mph. I connected the speedo from GMPP harness bulkhead connector pin D (brown) which presumably goes to ECM X1 pin 39 (vehicle speed out). Earlier the speedo was splitted from VSS Hi signal directly from sensor in the transmission tail.

Tune attached together with a short log on running on the lift.

This seems to operate with the LS2 throttle body. I did have to relocate pins in the pedal connector though. No DTC:s and it follows the pedal all the way.

[Tapi]

Now I have tested different variations of speedo calibration without success.

Trans output shaft speed shows zero all the time. But at the same time I can see the vehicle speed increasing when I run it up to 13 mph and up above that the speed decreases even though the tires are spinning faster. There is just one VSS and I assume the vahicle speed comes from there?
I also have zero on transmission fluid temp and Trans shift mode shows "Unknown: 0b".

Any suggestions what to do next?

[blindsquirrel]

I have never seen Trans Shift Mode display anything that looked valid, delete that channel. You can see what it's doing with Trans Current Gear, PRNDL Status, and Trans Pressure Mode.

You have the VSS wired to the TCM now as it would be in the Trailblazer? I assume the original setup with the standalone trans had VSS wired direct to the ECM.

What transmission? 60E with no ISS?