P161B-BATTERY DISCONNECT / TCM INTERNAL

For a complete wiring diagram Refer to Section 8W.

Theory of Operation

The Transmission Control Module (TCM) calculates the checksum in the EEPROM and compares it to the stored checksum value. If the calculated checksum value does not match the stored checksum value the TCM sets the DTC and illuminates the MIL.

When Monitored:
One time at every ignition on cycle.
Set Condition:
When the calculated checksum does not equal the stored checksum configuration or loss of power to the controller. It takes one trip of problem identification to set the MIL.

Possible Causes

WRONG VEHICLE CALIBRATION

FUSED B(+), TRANSMISSION CONTROL OUTPUT, AND/OR GROUND OPEN

TRANSMISSION CONTROL MODULE (TCM)

Always perform the CVT Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - CVT - STANDARD PROCEDURE)

1. CHECK TO SEE IF THE DTC IS ACTIVE

With the scan tool, read Transmission DTCs.

Is the status Active for P161B?

Yes

Go To 3

Go To 2

2. CHECK FOR OTHER DTCS

With the scan tool, read Transmission DTCs.

Is the status Active for P0602 also?

Yes

Refer to the Transmission category and perform diagnostic procedure for P0602.

Go To 3

3. CHECK THE TCM

Has the TCM been flashed, a new TCM installed or the battery or TCM disconnected with the ignition in the On or Accessory position?

Yes

This is a normal condition. Cycle the ignition off for 4 seconds and turn the ignition back on. Erase DTCs and cycle the ignition off again for 4 seconds and turn the ignition back on. Read TCM DTCs. If the DTC resets and remains active - Go To 4. If the DTC does not reset perform CVT TRANSMISSION VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - CVT - STANDARD PROCEDURE)

Using the schematics as a guide, check the Transmission Control Module (TCM) terminals for corrosion, damage, or terminal push out. Pay particular attention to all power and ground circuits.
NOTE: A loss of the TCM Fused B(+), TCM ground, and/or the Transmission Control Output circuits can cause this fault to set.
Check for any Service Bulletins for possible causes that may apply. If no problems are found, replace and program the TCM per the Service Information.
Perform CVT TRANSMISSION VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - CVT - STANDARD PROCEDURE)

4. CHECK IF THE RIGHT PART NUMBER IS USED

With the scan tool, check the TCM part number and compare it to the vehicle configuration.

Does the controller have the right part number?

Yes

Using the schematics as a guide, check the Transmission Control Module (TCM) terminals for corrosion, damage, or terminal push out. Pay particular attention to all power and ground circuits.

NOTE: A loss of the TCM Fused B(+), TCM ground, and/or the Transmission Control Output circuits can cause this fault to set.

Check for any Service Bulletins for possible causes that may apply. If no problems are found, replace and program the TCM per the Service Information.

Perform CVT TRANSMISSION VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - CVT - STANDARD PROCEDURE)

Do to the configuration mismatch the controller will need to be replaced with the proper part number for the configuration of the vehicle. Replace and program the TCM per the Service Information.
Perform CVT TRANSMISSION VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - CVT - STANDARD PROCEDURE)