DTC U0101-00: Lost Communication With the PCM (PGM-FI system, Without CAN gateway)

NOTE: 

• Before doing this troubleshooting procedure, find out if the vehicle was in a collision. If so, verify that all the required components were replaced with new components of the correct part number, and that they were properly installed - Refer to: SRS Component Replacement/Inspection After Deployment (2015-17) or SRS Component Replacement/Inspection After Deployment (2018-19) .
• Before doing this troubleshooting procedure, review SRS Precautions and Procedures , General Troubleshooting Information - Refer to: How to Troubleshoot the SRS (2015-17) or How to Troubleshoot the SRS (2018-19) , and 12 Volt Battery Terminal Disconnection and Reconnection .
• Before replacing the SRS unit, check the SRS unit software version with the HDS. If the software version is not the latest, update the SRS unit software , and retest.

DTC (SRS)

1. Body electrical system check

   -1. Check for any F-CAN and B-CAN communication DTCs with the HDS.

   DTC Description	DTC

   Are there any communication DTCs?

   YES 

   Go to the appropriate DTC troubleshooting.

   NO 

   Go to step 2.

2. DTC check

   -1. Clear the DTCs with the HDS.

   - 2. Turn the vehicle to the ON mode, then wait for 10 seconds.

   - 3. Check for DTCs with the HDS.

   DTC Description	DTC
   U0101-00 Lost communication with the PCM (PGM-FI system)

   Is DTC U0101-00 indicated?

   YES 

   Go to step 3.

   NO 

   Intermittent failure, the system is OK at this time. Go to Troubleshooting Intermittent Failures - Refer to: How to Troubleshoot the SRS (2015-17) or How to Troubleshoot the SRS (2018-19) . If another DTC is indicated, troubleshoot the DTC.

3. PGM-FI system check

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

   - 2. Start the engine, and see if the malfunction indicator lamp (MIL) also stays on.

   Does the MIL stay on longer than 30 seconds?

   YES 

   Go to the Fuel and Emissions Systems General Troubleshooting Information - Refer to applicable year/vehicle:

   • How to Troubleshoot the Fuel and Emissions Systems (L4)
   • How to Troubleshoot the Fuel and Emissions Systems(V6, Without Auto Idle Stop System) .
   • How to Troubleshoot the Fuel and Emissions Systems(V6, With Auto Idle Stop System)

   NO (L4 engine)

   Go to step 4.

   NO (V6 engine)

   Go to step 5.

4. Open wire check (F-CAN_H, F-CAN_L lines)

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

   - 2. Jump the SCS line with the HDS.

   NOTE:  This step must be done to protect the PCM from damage.

   - 3. Disconnect the following connector.

   Disconnect PCM connector A (51P)

   - 4. Disconnect the negative cable from the 12 volt battery, then wait at least 3 minutes.

   - 5. Disconnect the following connector.

   SRS unit connector A (39P)

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

   Test condition	Vehicle OFF (LOCK) mode
   	PCM connector A (51P): disconnected
   	SRS unit connector A (39P): disconnected
   Test point 1	SRS unit connector A (39P) No. 20 - Refer to: SRS Unit Connector for Inputs and Outputs (2015-17) or SRS Unit Connector for Inputs and Outputs (2018-19)
   Test point 2	PCM connector A (51P) No. 2 - Refer to appropriate year/vehicle: PCM Connector for Inputs and Outputs (L4) (2015-17) PCM Connector for Inputs and Outputs (L4) (2018-19) PCM Connector for Inputs and Outputs (V6, Without Auto Idle Stop System, 2015-17) PCM Connector for Inputs and Outputs (V6, With Auto Idle Stop System, 2015-17) PCM Connector for Inputs and Outputs (V6) (2018-19)

   Test point 1	SRS unit connector A (39P) No. 21 - Refer to: SRS Unit Connector for Inputs and Outputs (2015-17) or SRS Unit Connector for Inputs and Outputs (2018-19)
   Test point 2	PCM connector A (51P) No. 3 - Refer to appropriate year/vehicle: PCM Connector for Inputs and Outputs (L4) (2015-17) PCM Connector for Inputs and Outputs (L4) (2018-19) PCM Connector for Inputs and Outputs (V6, Without Auto Idle Stop System, 2015-17) PCM Connector for Inputs and Outputs (V6, With Auto Idle Stop System, 2015-17) PCM Connector for Inputs and Outputs (V6) (2018-19)

   Is there continuity?

   YES 

   The F-CAN_H and F-CAN_L wires are OK. Faulty SRS unit or poor connection at SRS unit connector A (39P) and the SRS unit. Check the connection; if the connection is OK, replace the SRS unit - Refer to: SRS Unit Removal and Installation (2015-17) or SRS Unit Removal and Installation (2018-19) . If the DTC does not clear, replace the engine compartment wire harness or the dashboard wire harness.

   NO 

   Open in the harness between SRS unit connector A (39P) terminal No. 20 and PCM connector A (51P) terminal No. 2, or between SRS unit connector A (39P) terminal No. 21 and PCM connector A (51P) terminal No. 3 (engine compartment wire harness or dashboard wire harness); replace the faulty harness, then clear the DTC.

5. Open wire check (F-CAN A_H, F-CAN A_L lines)

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

   - 2. Jump the SCS line with the HDS.

   NOTE:  This step must be done to protect the PCM from damage.

   - 3. Disconnect the following connector.

   Disconnect PCM connector A (51P)

   - 4. Disconnect the negative cable from the 12 volt battery, then wait at least 3 minutes.

   - 5. Disconnect the following connector.

   SRS unit connector A (39P)

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

   Test condition	Vehicle OFF (LOCK) mode
   	PCM connector A (51P): disconnected
   	SRS unit connector A (39P): disconnected
   Test point 1	SRS unit connector A (39P) No. 20 - Refer to: SRS Unit Connector for Inputs and Outputs (2015-17) or SRS Unit Connector for Inputs and Outputs (2018-19)
   Test point 2	PCM connector A (51P) No. 9 - Refer to appropriate year/vehicle: PCM Connector for Inputs and Outputs (L4) (2015-17) PCM Connector for Inputs and Outputs (L4) (2018-19) PCM Connector for Inputs and Outputs (V6, Without Auto Idle Stop System, 2015-17) PCM Connector for Inputs and Outputs (V6, With Auto Idle Stop System, 2015-17) PCM Connector for Inputs and Outputs (V6) (2018-19)

   Test point 1	SRS unit connector A (39P) No. 21 - Refer to: SRS Unit Connector for Inputs and Outputs (2015-17) or SRS Unit Connector for Inputs and Outputs (2018-19)
   Test point 2	PCM connector A (51P) No. 10 - Refer to appropriate year/vehicle: PCM Connector for Inputs and Outputs (L4) (2015-17) PCM Connector for Inputs and Outputs (L4) (2018-19) PCM Connector for Inputs and Outputs (V6, Without Auto Idle Stop System, 2015-17) PCM Connector for Inputs and Outputs (V6, With Auto Idle Stop System, 2015-17) PCM Connector for Inputs and Outputs (V6) (2018-19)

   Is there continuity?

   YES 

   The F-CAN A_H, F-CAN A_L wires are OK. Faulty SRS unit or poor connection at SRS unit connector A (39P) and the SRS unit. Check the connection; if the connection is OK, replace the SRS unit - Refer to: SRS Unit Removal and Installation (2015-17) or SRS Unit Removal and Installation (2018-19) . If the DTC does not clear, replace the engine compartment wire harness or the dashboard wire harness.

   NO 

   Open in the harness between SRS unit connector A (39P) terminal No. 20 and PCM connector A (51P) terminal No. 9, or between SRS unit connector A (39P) terminal No. 21 and PCM connector A (51P) terminal No. 10 (engine compartment wire harness or dashboard wire harness); replace the faulty harness, then clear the DTC.