Results 1 to 10 of 10

Thread: V2 CTS V TH400 Swap Help Request: No Dash speedo reading

  1. #1
    Potential Tuner
    Join Date
    Jun 2017
    Posts
    6

    V2 CTS V TH400 Swap Help Request: No Dash speedo reading

    Looking to see if someone can point me in the right direction. Just recently swapped trans on 2011 CTS V. Went from a 6L90 to a Manual Valve Body TH400. All gauges read correctly except for the dash speedo. It switched trans to manual and disabled the VSS. I get nothing on the speedo. When I log in hptuners, I do get a speed reading for driven and undriven wheels. Is there a way to direct the speedo to read from the wheel sensor? Would flashing in a manual cal fix the problem as I don?t think the M6?s had a VSS. Appreciate any guidance on a possible fix.

  2. #2
    Senior Tuner
    Join Date
    Jun 2004
    Location
    405
    Posts
    2,287
    Should be able to do something similar. I did this on a 98 Z28 that swapped to a T-350.

    https://ls1tech.com/forums/automatic...eedo-work.html

    And M6s had a VSS

  3. #3
    Tuning Addict blindsquirrel's Avatar
    Join Date
    Apr 2017
    Location
    Meridian MS
    Posts
    7,449
    The auto trans ECM OS is expecting to see the VSS come in over serial data from the no-longer-present TCM. The manual trans OS has the VSS wired direct into the ECM.

  4. #4
    Potential Tuner
    Join Date
    Jun 2017
    Posts
    6
    Quote Originally Posted by blindsquirrel View Post
    The auto trans ECM OS is expecting to see the VSS come in over serial data from the no-longer-present TCM. The manual trans OS has the VSS wired direct into the ECM.
    What is the speed sensor data source on the manual OS (VSS,Wheel Sensor)? It looks like the wheel speed sensor is providing a speed input. What problems would I encounter in flashing a manual OS over my Auto OS? Note: its a Gen IV V8. Thanks in advance.

  5. #5
    Advanced Tuner
    Join Date
    Aug 2010
    Location
    Detroit, MI
    Posts
    926
    I was able to tie in a TH400 style reluctor on my Colorado with the T42. Just needed a 10k resistor to shunt some current from the sensor to ground, otherwise it saturated the VSS input on the TCM. That's an option if you wanted to not get rid of the TCM and have it work like stock.

  6. #6
    Potential Tuner
    Join Date
    Jun 2017
    Posts
    6
    The TCM was removed as it was part of the OEM 6L90 that was replaced.

  7. #7
    Senior Tuner DSteck's Avatar
    Join Date
    Mar 2008
    Location
    St. Louis, MO
    Posts
    4,856
    Most wind up running a manual OS. I have these OBD2 pass through devices I made that could potentially replicate a T43's communications, pull speed from a wheel speed sensor, and convert it back into a CAN message the ECM can use. The problem is the time to develop that is going to be expensive.

    DSX Tuning - Authorized HP Tuners Dealer
    http://www.dsxtuning.com
    http://www.facebook.com/dsx.tuning
    Just say no to bull s***.
    IF YOU WANT HELP, POST A FILE!

  8. #8
    Potential Tuner
    Join Date
    Jun 2017
    Posts
    6
    Quote Originally Posted by DSteck View Post
    Most wind up running a manual OS. I have these OBD2 pass through devices I made that could potentially replicate a T43's communications, pull speed from a wheel speed sensor, and convert it back into a CAN message the ECM can use. The problem is the time to develop that is going to be expensive.
    . When running a manual OS, where does the speed signal come from? VSS or wheel sensor?

  9. #9
    Senior Tuner DSteck's Avatar
    Join Date
    Mar 2008
    Location
    St. Louis, MO
    Posts
    4,856
    You need a simulated VSS. I made a module for a guy one time that generated one based off of a wheel speed sensor. It just crapped out a variable frequency based on rear wheel speed. He got it to work.

    DSX Tuning - Authorized HP Tuners Dealer
    http://www.dsxtuning.com
    http://www.facebook.com/dsx.tuning
    Just say no to bull s***.
    IF YOU WANT HELP, POST A FILE!

  10. #10
    Potential Tuner
    Join Date
    Jun 2017
    Posts
    6