DTC U1073 (No. 1073): Control Module Communication Bus Off: Troubleshooting

WARNING: This page is about a different car, the 2006 Suzuki Grand Vitara. However, it is still accessible from the selected car via links, so may be relevant.

DTC TROUBLESHOOTING CHART

Step	Action	YES	NO
1	Check each control unit connectors Check connection of connectors of all control modules communicating by means of CAN and reconnect securely. Recheck DTC and reconnect securely. Is DTC U1073 detected?	Go to Step 2.	Intermittent trouble. Check for intermittent referring to INTERMITTENT AND POOR CONNECTION INSPECTION .
2	CAN communication circuit check Turn ignition switch to OFF position. Disconnect connectors of all control modules communicating by means of CAN. Check CAN communication circuit between control modules for open, short and high resistance. Is each CAN communication circuit in good condition?	Go to Step 3.	Repair circuit.
3	Check DTC in BCM Turn ignition switch to OFF position. 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 U1073 detected?	Disconnect connectors of control modules other than the one whose connector is disconnected in Step 3) one by one and check that DTC U1073 is detected by BCM each time connector is disconnected. When DTC U1073 is not detected by BCM while checking in this way, go to description under "NO" below. If DTC U1073 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 3). If circuit is OK, substitute a known-good control module disconnected in Step 3) and recheck.