DTC U1100 (No. 1100): Lost Communication With ECM: Troubleshooting

DTC TROUBLESHOOTING CHART

Step	Action	YES	NO
1	Check DTC in BCM Is DTC U1100 (No. 1100) and DTC U1073 (No. 1073) detected together?	Go to DTC U1073 (NO. 1073): CONTROL MODULE COMMUNICATION BUS OFF .	Go to Step 2.
2	Check DTC in ECM Check DTC for ECM. Is DTC U0073 detected?	Go to DTC U0073: CONTROL MODULE COMMUNICATION BUS OFF .	Go to Step 3.
3	Check each control module connectors Check connection of connectors of all control modules communicating by means of CAN. Recheck BCM for DTC. Is DTC U1100 (No. 1100) detected?	Go to Step 4.	Intermittent trouble. Check for intermittent referring to INTERMITTENT AND POOR CONNECTION INSPECTION .
4	CAN communication circuit check Turn ignition switch to OFF position. Disconnect connectors of BCM, ECM and ABS or ESP® control modules communicating by means of CAN. Check each CAN communication circuit between ECM and ABS or ESP® control module, between BCM and ABS or ESP® control module for open, short and high resistance. Is each CAN communication circuit in good condition?	Go to Step 5.	Repair circuit.
5	DTC check Turn ignition switch to OFF position. Disconnect connectors of all control modules communicating by means of CAN. Connect connectors to BCM, ECM and ABS or ESP® control module. Recheck BCM for DTC. Is DTC U1100 (No. 1100) detected?	Go to Step 6.	Go to Step 8.
6	DTC Check Check DTC for ABS or ESP® control module. Is DTC U1100 detected by ABS or ESP® control module?	Check ECM power and ground circuit. If circuit is OK, substitute a known-good ECM and recheck.	Go to Step 7.
7	CAN communication circuit check Turn ignition switch to OFF position. Disconnect connectors of ECM and BCM communicating by means of CAN. Measure resistance at following terminals. Between "WHT/BLU" and "WHT" wire terminals of ABS or ESP® control module connector Between "WHT/RED" and "RED" wire terminals of ABS or ESP® control module connector Is resistance below 1 Ω?	Substitute a known-good BCM and recheck.	Substitute a known-good ABS or ESP® control module and recheck.
8	CAN communication circuit check Turn ignition switch to OFF position. Check each CAN communication circuit between disconnected control modules (other than ECM, BCM and ABS or ESP® control module) for open, short and high resistance. Is each CAN communication circuit in good condition?	Go to Step 9.	Repair circuit.
9	Check DTC in BCM Connect connectors of disconnected control modules communicating by means of CAN. Disconnect connector from any one of control modules other than BCM. Recheck DTC for BCM. Is DTC U1100 detected?	Disconnect connectors of control modules other than the one whose connector is disconnected in Step 2) one by one and check that DTC U1100 is detected by BCM each time connector is disconnected. When DTC U1100 is not detected by BCM while checking in this way, go to description under "NO" below. If DTC U1100 is detected by BCM even when connectors of all control modules that use CAN communication with BCM are disconnected, substitute a known-good BCM and recheck.	Check power and ground circuit of control module disconnect in Step 2). If circuit is OK, substitute a known-good control module disconnected in Step 2) and recheck.