DTC Troubleshooting

WARNING: This page is about a different car, the 2011 Suzuki SX4. However, it is still accessible from the selected car via links, so may be relevant.

B1551: SYMPTOM TROUBLESHOOTING REFERENCE CHART

Step	Action	YES	NO
1	Was "Air Conditioning System Check" performed?	Go to Step 2.	Go to AIR CONDITIONING SYSTEM CHECK: AUTO A/C .
2	Backup power supply circuit fuse check Check backup power supply circuit fuse for blowing. Is fuse(s) blown?	Replace blown fuse and check for short in backup power supply circuit.	Go to Step 3.
3	Wire harness check Turn ignition switch to OFF position. Disconnect connectors from BCM and HVAC control module. Check for proper connection to serial communication circuit terminal of BCM and HVAC control module connectors. If OK, check that serial communication circuit is as follows. Wiring harness resistance of serial communication circuit is less than 3 Ω Insulation resistance between serial communication circuit terminal and vehicle body ground is Infinity Circuit voltage of serial communication circuit is 0 - 1 V with ignition switch turned ON Are they in good condition?	Go to Step 4.	Serial communication circuit is open, short or high resistance.
4	Communication data check Connect connectors to BCM and HVAC control module with ignition switch turned OFF. Check that serial communication signal is output from BCM referring to "Voltage Check" under INSPECTION OF BCM AND ITS CIRCUITS . Is serial communication signal output?	Substitute a known-good HVAC control module and recheck.	Substitute a known-good BCM and recheck.