Transmission Control Module (TCM)

In 2017 MY all 10R80 applications will use TCMs. In future years transmission controls will be integrated into the Powertrain Control Module (PCM) for gas engine applications, but diesel engine applications will continue to use a TCM.

The TCM has the same module diagnostics as an ECM or PCM - see miscellaneous CPU tests for details.

Module DTCs 

TCM Voltage 

If the system voltage at the TCM is outside of the specified 10 to 17 volt range while the engine is running a fault will be stored.

Ignition Switch Run Position (ISPR) 

The 10R TCM ignition status 2 ways:

• CAN message from the Body Control Module
• ISPR Hardwire

The TCM will wake on CAN or ISPR high, and will remain awake if the ignition is on. Since the information is provided redundantly to the TCM the ISPR wire failing open has no impact on function. If ISPR fails short to power the TCM will not be able to power down, but otherwise provides normal function.

The TCM has a diagnostic that compares the CAN message to ISPR hardwire.

Transmission Identification (TRID) block 

During the build process transmission hardware characterization data is captured. The TRID data shows where a specific transmission's components lie within the production variability. This data is flashed onto the PCM or TCM in the vehicle assembly plant, allowing transmission controls to meet its shift quality targets on a new, unadapted vehicle. The TRID data comes with a version number and checksum.

If the TRID is invalid or missing shift quality may be adversely affected, to insure a vehicle is never released to a customer without a valid TRID the DTC's are 1 trip MIL AND the transmission will be limited one or two forward gears (1st and 3rd or just 3rd gear). This will allow the vehicle to be moved to a repair area to correct the TRID, but insure a vehicle is not released to a customer without this data.

The diagnostics can detect:

The 10R TCM is connected to 2 CAN networks:

1. High Speed CAN network 1 (HS1) - one of 3 vehicle CAN networks (HS1, HS2, HS3) with a gateway module to move data from one vehicle CAN bus to another. The TCM receives messages from the following modules on the HS1 CAN bus:
   • Engine Control Module (ECM)
   • Body Control Module (BCM)
   • Gear Shift Module (GSM) - shift by wire applications only, starting in 18 MY TCM will receive redundant information on both CAN buses from the GSM, allowing normal control of the shift by wire system if a single CAN bus fault is present. GSM is on HS2 with messages gatewayed to HS1
   • Anti-lock Brake System Module (ABS) - on HS2, messages gatewayed to HS1
   • Instrument Panel Cluster (IPC) - gatewayed to HS1
   • Gateway Module (GWM) - moves data between different vehicle CAN buses
   • Transfer Case Control Module (TCCM) - if present, gatewayed to HS1
   • Restraints Control Module (RCM) - starting in 18 MY TCM will use data from the RCM on shift by wire applications, gatewayed to HS1
2. Powertrain Subnet (PT subnet) - a private CAN bus added to reduce loading on HS1. Some signals transmitted ECM to TCM on other applications are moved from HS1 to PT subnet. ECM to TCM communications require both HS1 and PT subnet up to have a full message set, there no redundancy in messages sent between ECM and TCM on HS1 and PT subnet. The TCM receives messages from the following modules on PT subnet:
   • Engine Control Module (ECM)
   • Gear Shift Module (GSM) - shift by wire applications only, starting in 18 MY TCM will receive redundant information on both CAN buses, allowing normal control of the shift by wire system if a single CAN bus fault is present

ECM - TCM CAN message traffic is split between the 2 CAN buses. The 2nd bus was added for bus loading, so there is little or no redundancy (both CAN buses must be up for normal control). The TCM will store the following CAN related DTC's

1. CAN bus down (HS1 - U0073, PT subnet - U0074)
2. Lost communication - CAN is up but the module is not communicating (ECM - U0100, GSM - U0103, ABS - U0121, BCM - U0140, GWM - U0146, IPC - U0155)
3. Invalid data received -module is on CAN but reporting faults in key signals (ECM - U401, GSM - U0404, ABS - U0415, BCM - U0422)