1. DTC B0021[1A] DTC description
When the ignition switch is turned ON, the SRS control unit performs diagnosis to determine whether serious malfunctions have occurred within the control unit. If the internal function is determined to be normal, the ignition voltage and the deployment circuit voltage are measured in order to verify that they are within the normal range. After that, the SRS control unit conducts a resistance measurement. It runs a light current of a known amount between the passenger curtain airbag deployment current output (High) circuit and the passenger curtain airbag deployment current output (Low) circuit, and measures the voltage difference between the terminals. The SRS control unit calculates the composite resistance of the passenger curtain airbag circuit, passenger curtain airbag, and connector terminal contact point.
2. Condition for setting DTC B0021[1A]
- The SRS control unit detects that the composite resistance of the passenger curtain airbag, passenger curtain airbag deployment current output (High) circuit, passenger curtain airbag deployment current output (Low) circuit, and connector terminal contact point is less than the specified value.
3. Action taken when DTC B0021[1A] sets
- SRS airbag warning light illuminates.
Warning
- During the maintenance work, do not hit or shake the SRS control unit when handling it.
- If the SRS control unit is not properly installed, the SRS control unit may cause malfunctions. This may result in deployment of the SRS airbag and personal injury.
Caution
- To prevent the SRS parts to be replaced from malfunctioning and generating a battery short circuit, make sure to disconnect the battery cable before replacing the parts.