U0146-08
U0146-08-LOST COMMUNICATION WITH CENTRAL GATEWAY-BUS SIGNAL / MESSAGE FAILURES
For a complete wiring diagram Refer to the Wiring Information.
Theory of Operation
The purpose of the diagnostic is to monitor the transmitted messages on the CAN BUS and the validity of the CAN signals. Several control units are connected to the CAN BUS which send their messages cyclically in a defined time window. The messages contain multiple signals representing vehicle information.
- When Monitored:
The circuit is continuously monitored with the ignition on.
Battery voltage between 10.0 and 16.0 volts.
Electronic Shift Module (ESM) is configured correctly.
- Set Condition:
BUS messages not received over the CAN C circuit for approximately two to five seconds.
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. NAG1 Pre-Diagnostic Troubleshooting Procedure
1. VERIFY THE DTC IS ACTIVE
NOTE: Make sure the battery voltage is between 10 and 16 volts before proceeding.
1. With the scan tool, read active DTCs.
Is this DTC active?
Yes
- Go To 2
No
- Perform the Stored Lost Communication DTCs diagnostic procedure. Stored Lost Communication DTCs
2. CHECK FOR ANY OF THE FOLLOWING ACTIVE DTCS
1. With the scan tool, read all active DTCs from all modules.
Does the scan tool display any active DTCs to the conditions listed above?
Yes
- Perform the appropriate diagnostic procedure.
No
- Go To 3
3. VERIFY THE ESM IS ACTIVE ON THE BUS
1. Turn the ignition ON.
2. With the scan tool, select Network Diagnostics.
3. Verify the ESM is active on the BUS.
Is the ESM active on the BUS?
Yes
- Go To 4
No
- Perform the NO RESPONSE FROM ESM (ELECTRONIC SHIFT MODULE) diagnostic procedure. No Response From ESM (Shift Lever Assembly)
4. CHECK FOR ADDITIONAL COMMUNICATION RELATED DTCS
1. With the scan tool, read all the DTCs.
Is there more than one module with active DTCs "Logged Against" the ESM ?
Yes
- Replace and program the ESM. Transmission Shifter - Removal.
- Perform the ESM VERIFICATION TEST. Verification Tests
No
- Go To 5
5. CLEAR DTC IN MODULE SETTING FAULT
1. With the scan tool, select the module setting the DTC against the ESM.
2. Clear active DTCs.
Is the DTC still active?
Yes
- Replace and program the module that set this DTC.
- Perform the ESM VERIFICATION TEST. Verification Tests
No
- Go To 6
6. CYCLE IGNITION
1. Cycle the ignition from RUN to OFF three times ending with the key in the RUN position.
Does the DTC become active?
Yes
- Go To 7
No
- The condition is not present at this time. Using the wiring diagram/schematic as a guide, inspect the wiring for chafed, pierced, pinched and partially broken wires and the wiring harness connectors for broken, bent, pushed out and corroded terminals.
- Perform the ESM VERIFICATION TEST. Verification Tests
7. CHECK FOR ADDITIONAL LOST COMMUNICATION FAULTS
1. With the scan tool, select Network Diagnostics.
Does the ABS and other CAN C BUS modules show Lost Communication with the remaining CAN C BUS modules?
Yes
- Go To 8
No
- Replace and program the module that set this DTC.
- Perform the ESM VERIFICATION TEST. Verification Tests
8. CHECK THE CAN C BUS (+) CIRCUIT FOR A SHORT TO VOLTAGE
1. Measure the voltage between the CAN C BUS (+) circuit and ground.
Is the voltage above 5.0 volts?
Yes
- Repair the short to voltage in the CAN C BUS (+) circuit.
- Perform the ESM VERIFICATION TEST. Verification Tests
No
- Go To 9
9. CHECK THE CAN C BUS (-) CIRCUIT FOR A SHORT TO GROUND
1. Turn the ignition OFF.
2. Measure the resistance between ground and the CAN C BUS (-) circuit.
Is the resistance below 10K Ohms?
Yes
- Repair the short to ground in the CAN C BUS (-) circuit.
- Perform the ESM VERIFICATION TEST. Verification Tests
No
- Using the schematics as a guide, check the ESM terminals for corrosion, damage or terminal push out. Pay particular attention to all power and ground circuits. If no problems are found, replace the Shift Lever Assembly. Transmission Shifter - Removal.
- Perform the ESM VERIFICATION TEST. Verification Tests