DTC B1794: Open in Occupant Classification ECU Battery Positive Line (TO 12/2010): Procedure

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

CHECK BATTERY
1. Measure the voltage of the battery.
  Voltage
  
  11 to 14 V
NG → REPLACE BATTERY

OK: Go to next step
CHECK FUSE
1. Check the ECU-B fuse.
  Resistance
  
  Below 1 Ω
NG → REPLACE FUSE

OK: Go to next step

CHECK WIRE HARNESS (SOURCE VOLTAGE)

Turn the ignition switch off.

Fig 1: Checking Occupant Classification ECU Connector Terminals (Source Voltage)
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Disconnect the negative (-) terminal cable from the battery.
Disconnect the connector from the occupant classification ECU.
Connect the negative (-) terminal cable to the battery.
Turn the ignition switch on (IG).

Measure the voltage and resistance according to the value(s) in the table below.

Standard voltage and resistance

Tester connection	Condition	Specified condition
O4-1 (+B) - Body ground	Always	10 to 14 V
O4-3 (GND) - Body ground	Always	Below 1 Ω
O4-7 (IG) - Body ground	Ignition switch on (IG)	10 to 14 V

NG → REPAIR OR REPLACE WIRE HARNESS

OK: Go to next step

CHECK DTC
1. Turn the ignition switch off.
2. Disconnect the negative (-) terminal cable from the battery.
3. Connect the connector to the occupant classification ECU.
4. Connect the Techstream to the DLC3.
5. Connect the negative (-) terminal cable to the battery.
6. Turn the ignition switch on (IG).
7. Clear the DTCs stored in the occupant classification ECU. Refer to DTC CHECK / CLEAR .
8. Clear the DTCs stored in the center airbag sensor assembly. Refer to DTC CHECK / CLEAR .
9. Turn the ignition switch off.
10. Turn the ignition switch on (IG), and wait for at least 10 seconds.
11. Using the Techstream, check the DTCs of the occupant classification ECU. Refer to DTC CHECK / CLEAR .
  OK
  
  DTC B1794 is not output.
  
  HINT:
  
  Codes other than DTC B1794 may be output at this time, but they are not related to this check.
NG → See step 5

OK → USE SIMULATION METHOD TO CHECK
REPLACE OCCUPANT CLASSIFICATION ECU
1. Turn the ignition switch off.
2. Disconnect the negative (-) terminal cable from the battery.
3. Replace the occupant classification ECU. Refer to REMOVAL .
NEXT: Go to next step
PERFORM ZERO POINT CALIBRATION
1. Connect the negative (-) terminal cable to the battery.
2. Connect the Techstream to the DLC3.
3. Turn the ignition switch on (IG).
4. Using the Techstream, perform the "Zero point calibration". Refer to INITIALIZATION .
  OK
  
  The "Zero Point Calibration is complete." is displayed.
NEXT: Go to next step
PERFORM SENSITIVITY CHECK
1. Using the Techstream, perform the "Sensitivity check". Refer to INITIALIZATION .
  Standard value
  
  27 to 33 kg (59.52 to 72.75 lb)
NEXT → END