8B
DTC B1021: Driver Air Bag Initiator Circuit Resistance High
Wiring Diagram
[A]: Shorting bar 3. “AIR BAG” fuse 6. Driver air bag (inflator) module
1. From main fuse 4. SDM 7. Ground for air bag system
2. Ignition switch 5. Contact coil assembly    
CAUTION:
• Be sure to perform Air Bag Diagnostic System Check before starting diagnosis according to the flow.
• When measurement of resistance or voltage is required in this flow, use a specified digital multimeter (Refer to Special Tool .) along with a correct terminal adapter from special tool (Connector test adapter kit).
• When a check for proper connection is required, refer to Inspection of Intermittents and Poor Connections .
• If there is open circuit in the air bag wire harness, connector or terminal is found damaged, replace the wire harness, connector and terminal as an assembly.
DTC Will Set when
The combined resistance of the driver air bag (inflator) module, contact coil assembly, harness wiring and connector terminal contact is above a specified value for specified time.
Flow Test Description
Step 1: Check whether malfunction is in contact coil and driver air bag (inflator) module or the others.
Step 2: Check driver air bag (inflator) module initiator circuit.
Step 3: Check whether malfunction is in contact coil or driver air bag (inflator) module.
Troubleshooting
Step Action YES NO
1
1) With ignition switch OFF, disconnect contact coil connector “G61” near the base of steering column.
2) Check proper connection to contact coil at terminals in contact coil connector “G61”.
3) If OK, then connect special tools (B) and (C) to contact coil connector “G61”.
Special Tool
(B) : 09932–75010
(C) : 09932–78340
With ignition switch ON, does DTC B1021 still exist?
Go to Step 2.
Go to Step 3.
2
1) With ignition switch OFF, disconnect SDM connector “G102”.
2) Check proper connection to SDM at terminals “G102-9” and “G102-10”.
3) If OK, release shorting bar in SDM connector inserting release tool (1) included in special tool (A).
4) Measure resistance between “G102-9” and “G102-10” terminals with connected special tools (B) and (C) to “G61” connector.
Special Tool
(A) : 09932–76010
(B) : 09932–75010
(C) : 09932–78340
Is resistance 4.5 Ω or less?
Substitute a known-good SDM and recheck.
Repair high resistance or open in “GRN” or “GRN/RED” wire circuit.
3
1) With ignition switch OFF, disconnect special tools (B) and (C) from “G61” connector, then reconnect contact coil connector “G61” located near the base of the steering column as it was.
2) Remove driver air bag (inflator) module from steering wheel referring to Driver Air Bag (Inflator) Module Removal and Installation .
3) Check proper connection to driver air bag (inflator) module at terminals in “Q02” connector.
4) If OK, then connect special tools (A), (B) and (D) to “Q02” connector.
Special Tool
(A) : 09932–76010
(B) : 09932–75010
(C) : 09932–78340
(D) : 09932–78310
With ignition switch ON, does DTC B1021 still exist?
Ignition switch OFF.
Replace contact coil assembly referring to Combination Switch (For Vehicle without Air Bag System)/Contact Coil and Combination Switch Assembly (For Vehicle with Air Bag System) Removal and Installation .
Ignition switch OFF.
Replace driver air bag (inflator) module referring to Driver Air Bag (Inflator) Module Removal and Installation .
NOTE:
Upon completion of inspection and repair work, perform the following items.
• Reconnect all air bag system components, ensure all components are properly mounted.
• Clear DTCs (Refer to DTC Clearance .), if any.
• Repeat Air Bag Diagnostic System Check to confirm that the trouble has been corrected.