Connecting the Twist Machine Paddle Shifter 3 to GM 6L80E

Overview 

Here are the basics on the GM tap up / tap down (TU/TD) functionality that allow using a paddle shifter. There are two common ways that GM provided this feature.

TU/TD via the Body Control Module (BCM)

• This method uses a resistor network of and switches connected to the BCM through a single wire.

• If your engine / trans combination is configured to use the BCM, then a BCM or other device to create the right data on the vehicle CAN bus to make the transmission respond to TU/TD.

• Most truck powertrains work this way, but can be reflashed to use the second method.

• Twist Machine does not currently support this method in an aftermarket configuration. It is possible to wire the paddle shifter receiver in parallel with existing switches in the vehcile.

TU/TD via the Transmission Control Module (TCM).

• The transmission must have this feature enabled either from the factory or through a reflash.

• Like the BCM method, this uses a network of resistors and switches connected though a single wire to pin 7 of the TCM. The resistor network is different than the one used on the BCM, and they are not interchangeable.

• This system is what you will get if you purchase a connect and cruise package from GM or similar.

• E67 computers can't ever use the TU/TD directly from the transmission, only E38 / T43 are supported.

• Many engine / transmission combinations are take-outs from existing cars.  Customers will have to have TU/TD enabled for the transmission if the donor car didn't have this feature, usually using HP Tuners or EFI Live. There is no way to tell unless you have had a tuner look at it for you using EFILive or HPTuners.

• Customers should check to see if the transmission main connector has pin 7 populated, and if so, where it goes in their harness.

• When the transmission is reflashed for TU/TD, you will have to choose which shift lever position TU/TD is active in. In HPTuners, the setup looks something like this:
  

  

• Further information can be found in the HP Tuners forum.

TCM Resistor Network

A harness is available from Twist Machine that has the resistor network for connecting between the Paddle Shifter and the 6L80E TCM, but it can be connected with the generic harness as well.

All resistors are 1%.