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.
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT:
- If troubleshooting (wire harness inspection) is difficult to perform, remove the front passenger seat installation bolts to see the under surface of the seat cushion.
- In the above case, hold the seat so that it does not tip over. Holding the seat for a long period of time may cause a problem, such as seat rail deformation. Hold the seat up only for as long as necessary.
PROCEDURE
1. CHECK DTC
(a) Turn the ignition switch to the on position.
(b) Clear the DTCs stored in the memory Reading and Clearing Diagnostic Trouble Codes.
HINT: First clear DTCs stored in the occupant classification ECU and then in the center airbag sensor assembly.
(c) Turn the ignition switch to the lock position.
(d) Turn the ignition switch to the on position.
(e) Check the 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.
OK -- USE SIMULATION METHOD TO CHECK
NG -- Continue to next step.
2. CHECK CONNECTION OF CONNECTORS
(a) Turn the ignition switch to the lock position.
(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 occupant classification ECU and the center airbag sensor assembly.
OK:
The connectors are properly connected.
NG -- CONNECT CONNECTORS
OK -- Continue to next step.
3. CHECK CENTER AIRBAG SENSOR CIRCUIT (TO B+)
(a) Disconnect the connectors from the occupant classification ECU and the center airbag sensor assembly.
(b) Connect the negative (-) terminal cable to the battery.
(c) Turn the ignition switch to the on position.
(d) Measure the voltage.
Standard voltage:
NG -- CHECK FLOOR WIRE (TO B+)
OK -- Continue to next step.
4. CHECK CENTER AIRBAG SENSOR CIRCUIT (FOR OPEN)
(a) Turn the ignition switch to the lock position.
(b) Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
(c) Using a service wire, connect K1-16 (FSP+) and K1-24 (FSP-) of connector B.
NOTE: Do not forcibly insert a service wire into the terminals of the connector when connecting.
(d) Measure the resistance.
Standard resistance:
NG -- CHECK FLOOR WIRE (FOR OPEN)
OK -- Continue to next step.
5. CHECK CENTER AIRBAG SENSOR CIRCUIT (FOR SHORT)
(a) Disconnect the service wire from connector B.
(b) Measure the resistance.
Standard resistance:
NG -- CHECK FLOOR WIRE (FOR SHORT)
OK -- Continue to next step.
6. CHECK CENTER AIRBAG SENSOR CIRCUIT (TO GROUND)
(a) Measure the resistance.
Standard resistance:
NG -- CHECK FLOOR WIRE (TO GROUND)
OK -- Continue to next step.
7. CHECK DTC
(a) Connect the connectors to the occupant classification ECU and the center airbag sensor assembly.
(b) Connect the negative (-) terminal cable to the battery.
(c) Turn the ignition switch to the on position.
(d) Clear the DTCs stored in the memory Reading and Clearing Diagnostic Trouble Codes.
HINT: First clear DTCs stored in the occupant classification ECU and then in the center airbag sensor assembly.
(e) Turn the ignition switch to the lock position.
(f) Turn the ignition switch to the on position.
(g) Check the 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.
OK -- USE SIMULATION METHOD TO CHECK
NG -- Continue to next step.
8. REPLACE OCCUPANT CLASSIFICATION ECU
(a) Turn the ignition switch to the lock position.
(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.
9. PERFORM ZERO POINT CALIBRATION
(a) Connect the negative (-) terminal cable to the battery.
(b) Connect a Techstream to the DLC3.
(c) Turn the ignition switch to the on position.
(d) Using the Techstream, perform the zero point calibration Programming and Relearning.
OK:
COMPLETED is displayed.
NEXT -- Continue to next step.
10. PERFORM SENSITIVITY CHECK
(a) Using a Techstream, perform the sensitivity check Programming and Relearning.
(1) Confirm that nothing is placed on the passenger seat.
(2) Confirm that the beginning sensor reading is within the standard range.
Standard range:
-3.2 to 3.2 kg (-7 to 7 lb)
(3) Place a 30 kg (66.14 lb) weight (e.g. a lead mass) onto the front passenger seat.
(4) Confirm that the sensitivity is within the standard range.
Standard range:
27 to 33 kg (59.52 to 72.75 lb)
HINT: When performing the sensitivity check, use a solid metal weight (the check result may not be accurate if a liquid weight is used).
NEXT -- Continue to next step.
11. CHECK DTC
(a) Turn the ignition switch to the on position.
(b) Clear the DTCs stored in the memory Reading and Clearing Diagnostic Trouble Codes.
HINT: First clear DTCs stored in the occupant classification ECU and then in the center airbag sensor assembly.
(c) Turn the ignition switch to the lock position.
(d) Turn the ignition switch to the on position.
(e) Check the 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 -- END
12. CHECK FLOOR WIRE (TO B+)
(a) Turn the ignition switch to the lock position.
(b) Disconnect the negative (-) terminal cable from the battery, and wait for at least 90 seconds.
(c) Disconnect the connectors from the floor wire and the No. 1 seat wire.
(d) Connect the negative (-) terminal cable to the battery.
(e) Turn the ignition switch to the on position.
(f) Measure the voltage.
Standard voltage:
NG -- REPAIR OR REPLACE FLOOR WIRE
OK -- REPLACE NO.1 SEAT WIRE
13. CHECK FLOOR WIRE (FOR OPEN)
(a) Disconnect the connectors from the floor wire and the No. 1 seat wire.
HINT: The service wire has already been inserted into connector B.
(b) Measure the resistance.
Standard resistance:
NG -- REPAIR OR REPLACE FLOOR WIRE
OK -- REPLACE NO.1 SEAT WIRE
14. CHECK FLOOR WIRE (FOR SHORT)
(a) Disconnect the connectors from the floor wire and the No. 1 seat wire.
(b) Measure the resistance.
Standard resistance:
NG -- REPAIR OR REPLACE FLOOR WIRE
OK -- REPLACE NO.1 SEAT WIRE
15. CHECK FLOOR WIRE (TO GROUND)
(a) Disconnect the connectors from the floor wire and the No. 1 seat wire.
(b) Measure the resistance.
Standard resistance:
NG -- REPAIR OR REPLACE FLOOR WIRE
OK -- REPLACE NO.1 SEAT WIRE