Toyota Venza: Open in Occupant Classification ECU Battery Positive Line (B1794)

Toyota Venza Service Manual / Supplemental Restraint Systems / Occupant Classification System / Open in Occupant Classification ECU Battery Positive Line (B1794)

DESCRIPTION

This circuit consists of the occupant classification ECU and power source circuit (battery, fuse and wire harness).

DTC B1794 is recorded when a malfunction is detected in the occupant classification ECU or power source circuit.

HINT:

If DTC B1794 is output after turning the ignition switch from off to ON and to off 50 times in a row when a malfunction occurs in the power circuit for the occupant classification system.

This DTC is output if a malfunction is detected even after being cleared unless the normal system code is input.

DTC No.	DTC Detection Condition	Trouble Area
B1794	The ignition switch is turned from off to ON, hold for 10 seconds or more, and turned off again 50 times in a row when a malfunction occurs in the power circuit for the occupant classification system. Occupant classification ECU malfunction	Battery ECU-B fuse Wire harness Occupant classification ECU

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 B1794 is output, perform troubleshooting for the DTC.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

Inspect the fuses for circuits related to this system before performing the following inspection procedure.

PROCEDURE

1.	CHECK BATTERY

(a) Measure the voltage of the battery.

Standard Voltage:

11 to 14 V

REPLACE BATTERY

2.	CHECK WIRE HARNESS (SOURCE VOLTAGE)

(a) Turn the ignition switch off.

(b) Disconnect the cable from the negative (-) battery terminal.

(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:

for Power Seat

Tester Connection	Condition	Specified Condition
S12-1 (+B) - Body ground	Always	11 to 14 V
S12-7 (IG) - Body ground	Ignition switch ON	11 to 14 V

for Manual Seat

Tester Connection	Condition	Specified Condition
M14-1 (+B) - Body ground	Always	11 to 14 V
M14-7 (IG) - Body ground	Ignition switch ON	11 to 14 V

(g) Turn the ignition switch off.

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

Standard Resistance:

for Power Seat

Tester Connection	Condition	Specified Condition
S12-3 (GND) - Body ground	Always	Below 1 Ω

for Manual Seat

Tester Connection	Condition	Specified Condition
M14-3 (GND) - Body ground	Always	Below 1 Ω

Text in Illustration

for Power Seat

for Manual Seat

Front view of wire harness connector

(to Occupant Classification ECU)

REPLACE WIRE HARNESS

CHECK DTC

(a) Turn the ignition switch off.

(b) Disconnect the cable from the negative (-) battery terminal.

(d) Connect the Techstream to the DLC3.

(e) Connect the cable to the negative (-) battery terminal.

(f) Turn the ignition switch to ON.

(g) Clear the DTCs stored in the occupant classification ECU (See page ).

(h) Clear the DTCs stored in the center airbag sensor assembly (See page ).

(i) Turn the ignition switch off.

(j) Turn the ignition switch to ON, and wait for at least 10 seconds.

(k) Using the Techstream, check for DTCs of the occupant classification ECU (See page ).

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.

USE SIMULATION METHOD TO CHECK

4.	REPLACE OCCUPANT CLASSIFICATION ECU

(a) Turn the ignition switch off.

(b) Disconnect the cable from the negative (-) battery terminal.

5.	PERFORM ZERO POINT CALIBRATION

(a) Connect the cable to the negative (-) battery terminal.

(b) Connect the Techstream to the DLC3.

(d) Using the Techstream, perform Zero Point Calibration (See page ).

OK:

"Zero Point Calibration is complete." is displayed.

6.	PERFORM SENSITIVITY CHECK

(a) Using the Techstream, perform Sensitivity Check (See page ).

Standard:

27 to 33 kg (59.5 to 72.8 lb)

END

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