DTC No. 31: Lost Communication With BCM: Troubleshooting

WARNING: This page is about a different variant/trim than selected.

TROUBLESHOOTING CHART

Step	Action	YES	NO
1	Was "Keyless Start System Check" performed?	Go to Step 2.	Go to KEYLESS START SYSTEM CHECK .
2	DTC Check Is DTC No. 33 detected?	Go to DTC NO. 33: CONTROL MODULE COMMUNICATION BUS OFF .	Go to Step 3.
3	DTC Check Check BCM for DTC referring to DTC CHECK Is DTC U1073, DTC U1100 or DTC U1101 detected?	Go to appropriate DTC diagnosis.	Go to Step 4.
4	BCM power and ground circuit check Check BCM power and ground circuit for condition referring to BCM POWER CIRCUIT AND GROUND CIRCUIT CHECK . Is it in good condition?	Go to Step 5.	Repair circuit.
5	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 keyless start control module and BCM for open, short and high resistance. Is CAN communication circuit in good condition?	Go to Step 6.	Repair circuit.
6	DTC check Connect connectors to BCM and keyless start control module. Recheck DTC for keyless start control module. Is DTC No. 31 detected?	Go to Step 7.	Go to Step 8.
7	DTC check Connect connectors of all control modules communicating by means of CAN. Check DTCs for ECM and TCM (A/T model). Is DTC U0140 detected by ECM and TCM (A/T model)?	Substitute a known-good BCM and recheck.	Substitute a known-good keyless start 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 BCM and keyless start control module) for open, short and high resistance. Is each CAN communication circuit in good condition?	Go to Step 9.	Repair circuit.
9	DTC check Turn ignition switch to OFF position. Connect connectors of disconnected control modules communicating by means of CAN. Disconnect connector of any one control module other than keyless start control module. Recheck DTC for keyless start control module. Is DTC No. 31 detected?	Using same method, disconnect connectors of control module other than keyless start control module one by one to check if DTC No. 31 is detected. If DTC No. 31 is detected even though connector of control module other than keyless start control module is disconnected, substitute a known-good keyless start control module and recheck.	Check power and ground circuit of disconnected control module. If circuit is OK, substitute a known-good disconnected control module and recheck.