DTC B1800: Short in D Squib Circuit; DTC B1801: Open in D Squib Circuit; DTC B1802: Short in D Squib Circuit (to Ground); DTC B1803: Short in D Squib Circuit (to +B): Procedure

1. Turn the ignition switch off.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

2. Disconnect the cable from the negative (-) battery terminal.
   WARNING:

   Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the SRS system.

3. Check that the connectors are properly connected to the horn button assembly, spiral cable sub-assembly and airbag ECU assembly.

   OK

   The connectors are properly connected.

   HINT: 

   If the connectors are not connected securely, reconnect the connectors and proceed to the next inspection.

4. Disconnect the connectors from the horn button assembly, spiral cable sub-assembly and airbag ECU assembly.
5. Check that the terminals of the connectors are not damaged.

   OK

   The terminals are not deformed or damaged.

6. Check that the spiral cable sub-assembly connector (on the horn button assembly side) is not damaged.

   OK

   The lock button is not disengaged, or the claw of the lock is not deformed or damaged.

7. Check that the short springs for the instrument panel wire and spiral cable sub-assembly with the activation prevention mechanism are not deformed or damaged.

   OK

   The short springs are not deformed or damaged.

   TEXT IN ILLUSTRATION
   
   

   *1	Horn Button Assembly
   *2	Spiral Cable Sub-assembly
   *3	Airbag ECU Assembly
   *4	Instrument Panel Wire

NG → REPLACE WIRE HARNESS 

OK: Go to next step 

1. Connect the instrument panel wire to the airbag ECU assembly and spiral cable sub-assembly.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

2. Connect SST (resistance 2.1 Ω) to connector E (orange connector).
   WARNING:

   Never connect the tester to the horn button assembly (driver side squib) for measurement, as this may lead to a serious injury due to airbag deployment.

   NOTE:

   • Do not forcibly insert SST into the terminals of the connector when connecting it.
   • Insert SST straight into the terminals of the connector.
   • SST: 09843-18061 
3. Connect the cable to the negative (-) battery terminal.
4. Clear the DTCs stored in memory. Refer to DTC CHECK / CLEAR [07/2013 - ] .
5. Turn the ignition switch off.
6. Turn the ignition switch to ON, and wait for at least 60 seconds.
7. Check for DTCs. Refer to DTC CHECK / CLEAR [07/2013 - ] .

   OK

   DTC B1800, B1801, B1802 or B1803 is not output.

   HINT: 

   Codes other than DTCs B1800, B1801, B1802 and B1803 may be output at this time, but they are not related to this check.

8. Turn the ignition switch off.
9. Disconnect the cable from the negative (-) battery terminal.
   WARNING:

   Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the SRS system.

10. Disconnect SST from connector E.
    TEXT IN ILLUSTRATION
    
    

    *1	Horn Button Assembly
    *2	Spiral Cable Sub-assembly
    *3	Airbag ECU Assembly
    *a	Front view of wire harness connector (to Horn Button Assembly)
    *b	Color: Orange

NG → See step   3 

OK → See step   7 

1. Disconnect the instrument panel wire from the airbag ECU assembly.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

2. Check for a short to B+ in the circuit.
   1. Connect the cable to the negative (-) battery terminal.
   2. Turn the ignition switch to ON.
   3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection	Condition	Specified Condition
      z7-2 (D+) - Body ground	Ignition switch ON	Below 1 V
      z7-1 (D-) - Body ground	Ignition switch ON	Below 1 V

   4. Turn the ignition switch off.
   5. Disconnect the cable from the negative (-) battery terminal.
      WARNING:

      Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the SRS system.

3. Check for an open in the circuit.
   1. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection	Condition	Specified Condition
      z7-2 (D+) - z7-1 (D-)	Always	Below 1 Ω

4. Check for a short to ground in the circuit.
   1. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection	Condition	Specified Condition
      z7-2 (D+) - Body ground	Always	1 MΩ or higher
      z7-1 (D-) - Body ground	Always	1 MΩ or higher

5. Check for a short in the circuit.
   1. Release the activation prevention mechanism built into connector B. Refer to DIAGNOSIS SYSTEM [07/2013 - ] .
   2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection	Condition	Specified Condition
      z7-2 (D+) - z7-1 (D-)	Always	1 MΩ or higher

   3. Restore the released activation prevention mechanism of connector B to the original condition.
      TEXT IN ILLUSTRATION
      
      

      *1	Horn Button Assembly
      *2	Spiral Cable Sub-assembly
      *3	Airbag ECU Assembly
      *a	Front view of wire harness connector (to Horn Button Assembly)
      *b	Color: Orange

NG → See step   5 

OK: Go to next step 

1. Connect the connectors to the horn button assembly and airbag ECU assembly.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

2. Connect the cable to the negative (-) battery terminal.
3. Clear the DTCs stored in memory. Refer to DTC CHECK / CLEAR [07/2013 - ] .
4. Turn the ignition switch off.
5. Turn the ignition switch to ON, and wait for at least 60 seconds.
6. Check for DTCs. Refer to DTC CHECK / CLEAR [07/2013 - ] .

   OK

   DTC B1800, B1801, B1802 or B1803 is not output.

   HINT: 

   Codes other than DTCs B1800, B1801, B1802 and B1803 may be output at this time, but they are not related to this check.

   TEXT IN ILLUSTRATION
   
   

   *1	Horn Button Assembly
   *2	Spiral Cable Sub-assembly
   *3	Airbag ECU Assembly

NG → See step   9 

OK → See step   10 

1. Disconnect the instrument panel wire from the spiral cable sub-assembly.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

2. Check for a short to B+ in the circuit.
   1. Connect the cable to the negative (-) battery terminal.
   2. Turn the ignition switch to ON.
   3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection	Condition	Specified Condition
      D52-1 (D-) - Body ground	Ignition switch ON	Below 1 V
      D52-2 (D+) - Body ground	Ignition switch ON	Below 1 V

   4. Turn the ignition switch off.
   5. Disconnect the cable from the negative (-) battery terminal.
      WARNING:

      Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the SRS system.

3. Check for an open in the circuit.
   1. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection	Condition	Specified Condition
      D52-1 (D-) - D52-2 (D+)	Always	Below 1 Ω

4. Check for a short to ground in the circuit.
   1. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection	Condition	Specified Condition
      D52-1 (D-) - Body ground	Always	1 MΩ or higher
      D52-2 (D+) - Body ground	Always	1 MΩ or higher

5. Check for a short in the circuit.
   1. Release the activation prevention mechanism built into connector B. Refer to DIAGNOSIS SYSTEM [07/2013 - ] .
   2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection	Condition	Specified Condition
      D52-1 (D-) - D52-2 (D+)	Always	1 MΩ or higher

   3. Restore the released activation prevention mechanism of connector B to the original condition.
      TEXT IN ILLUSTRATION
      
      

      *1	Horn Button Assembly
      *2	Spiral Cable Sub-assembly
      *3	Airbag ECU Assembly
      *4	Instrument Panel Wire
      *a	Front view of wire harness connector (to Spiral Cable Sub-assembly)

NG → REPLACE INSTRUMENT PANEL WIRE 

OK: Go to next step 

1. Check for a short to B+ in the circuit.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   1. Connect the cable to the negative (-) battery terminal.
   2. Turn the ignition switch to ON.
   3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection	Condition	Specified Condition
      z7-2 (D+) - Body ground	Ignition switch ON	Below 1 V
      z7-1 (D-) - Body ground	Ignition switch ON	Below 1 V

   4. Turn the ignition switch off.
   5. Disconnect the cable from the negative (-) battery terminal.
      WARNING:

      Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the SRS system.

2. Check for an open in the circuit.
   1. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection	Condition	Specified Condition
      z7-2 (D+) - z7-1 (D-)	Always	Below 1 Ω

3. Check for a short to ground in the circuit.
   1. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection	Condition	Specified Condition
      z7-2 (D+) - Body ground	Always	1 MΩ or higher
      z7-1 (D-) - Body ground	Always	1 MΩ or higher

4. Check for a short in the circuit.
   1. Release the activation prevention mechanism built into connector D. Refer to DIAGNOSIS SYSTEM [07/2013 - ] .
   2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection	Condition	Specified Condition
      z7-2 (D+) - z7-1 (D-)	Always	1 MΩ or higher

   3. Restore the released activation prevention mechanism of connector D to the original condition.
      TEXT IN ILLUSTRATION
      
      

      *1	Horn Button Assembly
      *2	Spiral Cable Sub-assembly
      *3	Airbag ECU Assembly
      *4	Instrument Panel Wire
      *a	Front view of wire harness connector (to Horn Button Assembly)
      *b	Color: Orange

NG → See step   8 

OK → See step   10