B1790
SUPPLEMENTAL RESTRAINT SYSTEMS: OCCUPANT CLASSIFICATION SYSTEM: B1790: Center Airbag Sensor Assembly Communication Circuit Malfunction
DTC B1790 - Center Airbag Sensor Assembly Communication Circuit Malfunction
DESCRIPTION
The center airbag sensor assembly communication circuit consists of the occupant classification ECU and the center airbag sensor assembly.
DTC B1790 is recorded when a malfunction is detected in the center airbag sensor assembly communication circuit.
HINT: When DTC B1650/32 is detected as a result of troubleshooting for the airbag system, check the DTCs stored in the occupant classification ECU. When DTC B1790 is output, perform troubleshooting for the DTC.
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT:
- If troubleshooting (wire harness inspection) is difficult to perform, remove the front passenger seat installation bolts to access the underside of the seat cushion.
- In the above case, hold the seat so that it does not fall down. Holding the seat for a long period of time may damage the seat or deform the seat rails. Hold the seat only as necessary.
PROCEDURE
1. CHECK CONNECTORS
(a) Turn the ignition switch off.
(b) Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
(c) Check that the connectors are properly connected to the occupant classification ECU and the center airbag sensor assembly.
OK:
The connectors are properly connected.
HINT: If the connectors are not connected securely, reconnect the connectors and proceed to the next inspection.
(d) Disconnect the connectors from the center airbag sensor assembly and the occupant classification ECU.
(e) Check that the terminals of the connectors are not damaged.
OK:
The terminals are not deformed or damaged.
NG -- REPLACE WIRE HARNESS
OK -- Continue to next step.
2. CHECK OCCUPANT CLASSIFICATION SYSTEM CIRCUIT (SHORT TO B+)
(a) Connect the cable to the negative (-) battery terminal.
(b) Turn the ignition switch to ON.
(c) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
NG -- CHECK NO. 2 FLOOR WIRE (SHORT TO B+)
OK -- Continue to next step.
3. CHECK OCCUPANT CLASSIFICATION SYSTEM CIRCUIT (OPEN)
(a) Turn the ignition switch off.
(b) Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
(c) Using SST, connect terminals 12 (FSR+) and 13 (FSR-) of connector B.
NOTE: Do not forcibly insert SST into the terminals of the connector when connecting the wire.
SST: 09843-18040
(d) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
NG -- CHECK NO. 2 FLOOR WIRE (OPEN)
OK -- Continue to next step.
4. CHECK OCCUPANT CLASSIFICATION SYSTEM CIRCUIT (SHORT)
(a) Disconnect SST from connector B.
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
NG -- CHECK NO. 2 FLOOR WIRE (SHORT)
OK -- Continue to next step.
5. CHECK OCCUPANT CLASSIFICATION SYSTEM CIRCUIT (SHORT TO GROUND)
(a) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
NG -- CHECK NO. 2 FLOOR WIRE (SHORT TO GROUND)
OK -- Continue to next step.
6. RECHECK FOR DTC
(a) Connect the connectors to the occupant classification ECU and the center airbag sensor assembly.
(b) Connect the Techstream to the DLC3.
(c) Connect the cable to the negative (-) battery terminal.
(d) Turn the ignition switch to ON.
(e) Clear the DTCs stored in the occupant classification ECU Reading and Clearing Diagnostic Trouble Codes.
(f) Clear the DTCs stored in the center airbag sensor assembly DTC Check / Clear.
(g) Turn the ignition switch off.
(h) Turn the ignition switch to ON.
(i) Using the Techstream, check for occupant classification ECU DTCs Reading and Clearing Diagnostic Trouble Codes.
OK:
DTC B1790 is not output.
HINT: Codes other than DTC B1790 may be output at this time, but they are not related to this check.
NG -- REPLACE OCCUPANT CLASSIFICATION ECU
OK -- USE SIMULATION METHOD TO CHECK
7. REPLACE OCCUPANT CLASSIFICATION ECU
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON.
(c) Using the Techstream, save the ECU data from the ECU currently installed on the vehicle Registration.
(d) Turn the ignition switch off.
(e) Disconnect the cable from the negative (-) battery terminal.
(f) Replace the occupant classification ECU Removal.
(g) Connect the cable to the negative (-) battery terminal.
(h) Turn the ignition switch to ON.
(i) Using the Techstream, load the previous ECU data stored into the new ECU Registration.
(j) Turn the ignition switch off.
(k) Turn the ignition switch to ON.
(l) Clear the DTCs stored in the memory Reading and Clearing Diagnostic Trouble Codes.
HINT: If the DTCs are not cleared at this time, past DTCs will remain.
NEXT -- Continue to next step.
8. RECHECK FOR DTC
(a) Turn the ignition switch to ON.
(b) Clear the DTCs stored in the occupant classification ECU Reading and Clearing Diagnostic Trouble Codes.
(c) Clear the DTCs stored in the center airbag sensor assembly DTC Check / Clear.
(d) Turn the ignition switch off.
(e) Turn the ignition switch to ON.
(f) Using the Techstream, check for occupant classification ECU DTCs Reading and Clearing Diagnostic Trouble Codes.
OK:
DTC B1790 is not output.
HINT: Codes other than DTC B1790 may be output at this time, but they are not related to this check.
NG -- REPLACE CENTER AIRBAG SENSOR ASSEMBLY
OK -- Continue to next step.
9. PERFORM SENSITIVITY CHECK
(a) Perform the sensitivity check Initialization.
NEXT -- END
10. REPLACE CENTER AIRBAG SENSOR ASSEMBLY
(a) Turn the ignition switch off.
(b) Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
(c) Replace the center airbag sensor assembly Removal.
NEXT -- Continue to next step.
11. PERFORM SENSITIVITY CHECK
(a) Perform the sensitivity check Initialization.
NEXT -- END
12. CHECK NO. 2 FLOOR WIRE (SHORT TO B+)
(a) Turn the ignition switch off.
(b) Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
(c) Disconnect the front seat wire RH connector from the No. 2 floor wire.
(d) Connect the cable to the negative (-) battery terminal.
(e) Turn the ignition switch to ON.
(f) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
NG -- REPLACE NO. 2 FLOOR WIRE
OK -- REPLACE FRONT SEAT WIRE RH
13. CHECK NO. 2 FLOOR WIRE (OPEN)
(a) Disconnect the front seat wire RH connector from the No. 2 floor wire.
HINT: SST has already been inserted into connector B.
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
NG -- REPLACE NO. 2 FLOOR WIRE
OK -- REPLACE FRONT SEAT WIRE RH
14. CHECK NO. 2 FLOOR WIRE (SHORT)
(a) Disconnect the front seat wire RH connector from the No. 2 floor wire.
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
NG -- REPLACE NO. 2 FLOOR WIRE
OK -- REPLACE FRONT SEAT WIRE RH
15. CHECK NO. 2 FLOOR WIRE (SHORT TO GROUND)
(a) Disconnect the front seat wire RH connector from the No. 2 floor wire.
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
NG -- REPLACE NO. 2 FLOOR WIRE
OK -- REPLACE FRONT SEAT WIRE RH