DTC U0101 (2016 2017 2018 PGM-FI System) (Without CAN Gateway)

DTC U0101 : F-CAN Malfunction (PCM-TCM)

NOTE: Before you troubleshoot, review the general troubleshooting information - Refer to: How to Troubleshoot the Fuel and Emissions Systems, or or How to Troubleshoot the Brake Booster Pressure Monitoring System (2016 2017 2018 2019 2020), or How to Troubleshoot the Fuel and Emissions Systems(With Auto Idle Stop System) (2016 2017 2018 2019 2020) .

DTC Description	Confirmed DTC	Pending DTC	Freeze Frame
U0101 F-CAN Malfunction (PCM-TCM)

DTC (PGM-FI)

Problem verification

-1. Turn the vehicle to the ON mode.

- 2. Clear the DTC with the HDS.

- 3. Check for Pending or Confirmed DTCs with the HDS.

DTC Description	Confirmed DTC	Pending DTC	Freeze Frame
U0101 F-CAN Malfunction (PCM-TCM)

Is DTC U0101 indicated?

YES

The failure is duplicated. Go to step 2.

Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the TCM and the PCM. If the freeze data/on-board snapshot of this DTC is recorded, try to reproduce the failure under the same conditions with the freeze data/on-board snapshot.

AT system check
-1. Check for communication to the AT system with the HDS.

Does the HDS communicate with the AT system?

YES

Go to step 3.

NO

Go to the automatic transmission symptom troubleshooting index .

Open wire check (F-CAN A_H line)

-1. Turn the vehicle to the OFF (LOCK) mode.

- 2. Jump the SCS line with the HDS.

- 3. Disconnect the following connectors.

PCM connector A (51P)

TCM 58P connector

- 4. Check for continuity between test points 1 and 2.

Test condition	Vehicle OFF (LOCK) mode
	PCM connector A (51P): disconnected
	TCM 58P connector: disconnected
Test point 1	TCM 58P connector No. 34
Test point 2	PCM connector A (51P) No. 9 - Refer to: PCM Connector for Inputs and Outputs (2017 2018 2019 2020), or PCM Connector for Inputs and Outputs (2016)

Is there continuity?

YES

The F-CAN A_H wire is OK. Go to step 4.

Repair an open in the F-CAN A_H wire between the PCM (A9) and the TCM.

Open wire check (F-CAN A_L line)

-1. Check for continuity between test points 1 and 2.

Test condition	Vehicle OFF (LOCK) mode
	PCM connector A (51P): disconnected
	TCM 58P connector: disconnected
Test point 1	TCM 58P connector No. 47
Test point 2	PCM connector A (51P) No. 10 - Refer to: PCM Connector for Inputs and Outputs (2017 2018 2019 2020), or PCM Connector for Inputs and Outputs (2016)

Is there continuity?

YES

The F-CAN A_L wire is OK. Go to step 5.

Repair an open in the F-CAN A_L wire between the PCM (A10) and the TCM.

Open wire check (F-CAN B_H line)

-1. Check for continuity between test points 1 and 2.

Test condition	Vehicle OFF (LOCK) mode
	PCM connector A (51P): disconnected
	TCM 58P connector: disconnected
Test point 1	TCM 58P connector No. 7
Test point 2	PCM connector A (51P) No. 11 - Refer to: PCM Connector for Inputs and Outputs (2016), or PCM Connector for Inputs and Outputs (2017 2018 2019 2020)

Is there continuity?

YES

The F-CAN B_H wire is OK. Go to step 6.

Repair an open in the F-CAN B_H wire between the PCM (A11) and the TCM.

Open wire check (F-CAN B_L line)

-1. Check for continuity between test points 1 and 2.

Test condition	Vehicle OFF (LOCK) mode
	PCM connector A (51P): disconnected
	TCM 58P connector: disconnected
Test point 1	TCM 58P connector No. 20
Test point 2	PCM connector A (51P) No. 12 - Refer to: PCM Connector for Inputs and Outputs (2016), or PCM Connector for Inputs and Outputs (2017 2018 2019 2020)

Is there continuity?

YES

The F-CAN B_L wire is OK. Update the TCM if it does not have the latest software, or substitute a known-good TCM , then recheck. If DTC U0101 goes away and the TCM was updated, troubleshooting is complete. If DTC U0101 goes away and the TCM was substituted, replace the original TCM .

Repair an open in the F-CAN B_L wire between the PCM (A12) and the TCM.