What this code means
B0028 can indicate an open circuit or increased resistance in the right side airbag inflator.
An open circuit is a break in an electrical path. Increased resistance means the path has more resistance than the procedure allows. For B0028, the path under investigation belongs to the front passenger's side airbag inflator. The diagnosis therefore needs to separate a problem associated with that component from a problem elsewhere in its circuit.
The front passenger's side airbag inflator, its connecting paths and the SRS unit are different possible fault areas. Naming the front passenger's side airbag inflator in the code does not make those possibilities interchangeable. The steps below narrow the fault area by changing a defined test condition and then checking the individual paths.
What the vehicle may do
- The SRS unit can store this code for high detection-line voltage.
Possible fault areas
- Possible fault areas include the front passenger's side airbag.
- The related wiring or SRS unit may also be involved.
The procedure moves through confirmation, an indirect component check and electrical-path checks. In the indirect check, the specified jumper connection is used exactly as described. The result determines whether the component or other related parts remain involved. The later measurements examine RFSA+ and RFSA- through the wiring between the side airbag connector and SRS unit.
Read the result criteria alongside the action that produces them. During the component check, a normal circuit-test result can point to a problem with the named component. During a wire check, an abnormal reading instead points to the checked path. These conclusions belong to different stages of the diagnosis.
Diagnostic path
Understand the stored condition
B0028 can point to an open circuit or increased resistance in the right side airbag inflator. The SRS unit stores this code when the voltage on its internal detection line is higher than a specified value.
Safety and collision history
Follow the SRS safety precautions and procedures. Use the specified 12 volt battery terminal disconnection and reconnection procedure. Find out whether the vehicle was in a collision. If it was, make sure all required components were replaced with new components of the correct part number. Also check that those components were properly installed.
Establish the confirmation condition
Turn the vehicle to ON mode. Wait for 10 seconds. This is the confirmation procedure you will use during the airbag circuit check.
Check the front passenger's side airbag circuit
Before you disconnect the SRS related connector, complete the 12 volt battery terminal disconnection procedure. Wait for at least 3 minutes. Disconnect the front passenger's side airbag inflator connector (2P). Install a jumper wire between terminals No. 1 and No. 2 of that connector. Run the confirmation procedure: turn the vehicle to ON mode, then wait for 10 seconds. Check for DTC B0028-13. A normal result means DTC B0028-13 is not indicated.
If the result is normal, there is a problem with the front passenger's side airbag. If the result is abnormal, there is a problem with other related components.
For the component test, a normal result means the stated DTC B0028-13 is not indicated after the specified test connection and confirmation. The procedure associates that normal test result with a problem in the front passenger's side airbag inflator. An abnormal result follows the branch for other related components.
Here, the word normal refers to the response of the circuit test. It does not describe a direct resistance measurement of the front passenger's side airbag inflator. The wire checks that follow use their own resistance criteria and therefore answer a different question. This distinction is the key to reading the component and circuit branches correctly.
Prepare for the RFSA+ and RFSA- wiring checks
Check the RFSA+ and RFSA- wires for an open circuit next. Before you disconnect the SRS related connectors, complete the 12 volt battery terminal disconnection procedure. Wait for at least 3 minutes. Disconnect SRS unit connector B (57P). The front passenger's side airbag inflator connector (2P) must also be disconnected. Keep both connectors disconnected for the following resistance measurements on each wire.
Check the RFSA+ wire
Keep IG Mode OFF for this measurement. To measure resistance, place one probe on SRS unit connector B (57P) terminal 5.
- Other probe: front passenger's side airbag inflator connector (2P) terminal 2.
- Normal reading: less than 1 ohm.
That means this wire passes the open-wire check. If the reading is abnormal, there is a problem in the circuit.
RFSA+ pairs SRS unit connector B terminal 5 with side-airbag connector terminal 2. RFSA- pairs SRS terminal 6 with airbag terminal 1. Each pair identifies a different path through the circuit. A matching terminal number is not a substitute for the named connector and the full pair given in the procedure.
The earlier jumper check produces the DTC result used for the component branch. These later checks produce resistance results for RFSA+ and RFSA-, using less than 1 ohm as the normal criterion under the stated preparation. An abnormal wire result belongs to that circuit path, whereas the component-test conclusion comes from the earlier code response.
Check the RFSA- wire
Keep IG Mode OFF for this measurement too. To measure resistance, place one probe on SRS unit connector B (57P) terminal 6.
- Other probe: front passenger's side airbag inflator connector (2P) terminal 1.
- Normal reading: less than 1 ohm.
That means this wire passes the open-wire check. If the reading is abnormal, there is a problem in the circuit.
Evaluate the SRS unit
If all the other inspection items are normal, the remaining cause is the SRS unit. Under that condition, there is a problem with the SRS unit.
Final check
These checks can narrow the fault to the airbag, its wiring, or the SRS unit.
Taken together, the results form a chain. The indirect component check establishes which branch to follow; the individual electrical checks identify an abnormal path; and the final SRS-unit conclusion depends on the earlier inspection items being normal. Keep the actual result beside the component or wire that was being checked. That makes the final decision traceable to the procedure, rather than to the wording of the stored code alone.
