B1790
SUPPLEMENTAL RESTRAINT SYSTEM: 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 see under the seat cushion.
- In the above case, hold the seat so that it does not fall down. Hold the seat only as necessary because holding the seat for a long period of time may cause seat rail deformation.
PROCEDURE
1. CHECK CONNECTORS
(a) Turn the ignition switch off.
(b) Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
(c) Check that the connectors are properly connected to the center airbag sensor assembly and the occupant classification ECU.
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 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 negative (-) terminal cable to the battery.
(b) Turn the ignition switch on (IG).
(c) Measure the voltage according to the value(s) in the table below.
Standard voltage:
NG -- CHECK FLOOR WIRE NO. 2 (SHORT TO B+)
OK -- Continue to next step.
3. CHECK OCCUPANT CLASSIFICATION SYSTEM CIRCUIT (OPEN)
(a) Turn the ignition switch off.
(b) Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
(c) Using SST, connect terminals 16 (FSP+) and 24 (FSP-) of connector B.
NOTE: Do not forcibly insert SST into the terminals of the connector when connecting.
SST: 09843-18040
(d) Measure the resistance according to the value(s) in the table below.
Standard resistance:
NG -- CHECK FLOOR WIRE NO. 2 (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 FLOOR WIRE NO. 2 (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 FLOOR WIRE NO. 2 (SHORT TO GROUND)
OK -- Continue to next step.
6. RECHECK DTC
(a) Connect the connectors to the occupant classification ECU and the center airbag sensor assembly.
(b) Connect Techstream to the DLC3.
(c) Connect the negative (-) terminal cable to the battery.
(d) Turn the ignition switch on (IG).
(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 Reading and Clearing Diagnostic Trouble Codes.
(g) Turn the ignition switch off.
(h) Turn the ignition switch on (IG).
(i) Using Techstream, check for DTCs of the occupant classification ECU DTC Check / Clear.
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) Turn the ignition switch off.
(b) Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
(c) Replace the occupant classification ECU Removal.
HINT: Perform the inspection using parts from a normal vehicle if possible.
NEXT -- Continue to next step.
8. PERFORM ZERO POINT CALIBRATION
(a) Connect the negative (-) terminal cable to the battery.
(b) Connect Techstream to the DLC3.
(c) Turn the ignition switch on (IG).
(d) Using Techstream, perform "zero point calibration" Programming and Relearning.
OK:
"Zero Point Calibration is complete." is displayed.
NEXT -- Continue to next step.
9. PERFORM SENSITIVITY CHECK
(a) Using Techstream, perform "sensitivity check" Programming and Relearning.
Standard:
27 to 33 kg (59.52 to 72.75 lb)
NEXT -- Continue to next step.
10. RECHECK DTC
(a) Turn the ignition switch on (IG).
(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 Reading and Clearing Diagnostic Trouble Codes.
(d) Turn the ignition switch off.
(e) Turn the ignition switch on (IG).
(f) Using Techstream, check for DTCs of the occupant classification ECU DTC Check / Clear.
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 -- END
11. CHECK FLOOR WIRE NO. 2 (SHORT TO B+)
(a) Turn the ignition switch off.
(b) Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
(c) Disconnect the front seat wire RH connector from the floor wire No. 2.
(d) Connect the negative (-) terminal cable to the battery.
(e) Turn the ignition switch on (IG).
(f) Measure the voltage according to the value(s) in the table below.
Standard voltage:
NG -- REPLACE FLOOR WIRE NO. 2
OK -- REPLACE FRONT SEAT WIRE RH
12. CHECK FLOOR WIRE NO. 2 (OPEN)
(a) Disconnect the front seat wire RH connector from the floor wire No. 2.
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 FLOOR WIRE NO. 2
OK -- REPLACE FRONT SEAT WIRE RH
13. CHECK FLOOR WIRE NO. 2 (SHORT)
(a) Disconnect the front seat wire RH connector from the floor wire No. 2.
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance:
NG -- REPLACE FLOOR WIRE NO. 2
OK -- REPLACE FRONT SEAT WIRE RH
14. CHECK FLOOR WIRE NO. 2 (SHORT TO GROUND)
(a) Disconnect the front seat wire RH connector from the floor wire No. 2.
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance:
NG -- REPLACE FLOOR WIRE NO. 2
OK -- REPLACE FRONT SEAT WIRE RH