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DTC No. 31: Lost Communication with BCM: Troubleshooting

WARNING: This page is about a different car, the 2008 Suzuki Grand Vitara and 2007 Suzuki Grand Vitara. However, it is still accessible from the selected car via links, so may be relevant.
TROUBLESHOOTING TABLE

Step Action YES NO
1  Was "Keyless Start System Check" performed?  Go to Step 2. Go to KEYLESS START SYSTEM CHECK .
2  DTC Check of keyless start control module 
Is DTC No. 33 detected? 		 Go to DTC NO. 33: CONTROL MODULE COMMUNICATION BUS OFF . Go to Step 3.
3  DTC Check of BCM 
  1. Check BCM for DTC by referring to DTC CHECK 

Is DTC U1073, DTC U1100 or DTC U1101 detected? 		 Go to applicable DTC diag flow. Go to Step 4.
4  CAN communication circuit check 
  1. Check connection of connectors of all control modules communicating by means of CAN.
  2. Disconnect connectors from BCM and keyless start control module.
  3. Check CAN communication circuit between BCM and keyless start control module for open, short and high resistance.

Is each CAN communication circuit in good condition? 		 Go to Step 5. Repair circuit.
5  CAN communication circuit check 
  1. Disconnect connectors of all control modules communicating by means of CAN.
  2. Check CAN communication circuit between control modules other than Step 4 for open, short and high resistance.

Is each CAN communication circuit in good condition? 		 Go to Step 6. Repair circuit.
6  DTC check of ECM 
  1. Connect connectors of disconnected control modules communicating by means of CAN.
  2. Check ECM for DTC.

Is DTC U0140 detected? 		 Check BCM power and ground circuit. If circuit is OK, substitute a known good BCM and recheck. Go to Step 7.
7  DTC check of keyless start control module 
  1. Turn ignition switch to OFF position.
  2. Disconnect connector of any one of control module other than keyless start control module.
  3. Recheck keyless start control module for DTC.

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 through 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 and recheck. If circuit is OK, substitute a known-good disconnected control module and recheck.
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