DTC B1071 Internal SDM Failure
Circuit Description
DTC B1071 is an indication of a potential internal SDM malfunction and will
set if any of the following conditions are detected:
- The VLR voltage is out of normal operating range. (Approximately 23 volts)
- The voltage measured at "Driver Side LO" is greater than three
volts, and the voltage measured at "Passenger Side LO" is less than or
equal to three volts, (DTC B1018).
- The voltage measured at "Driver Side LO" is less than or equal
to three volts, and the voltage measured at "Passenger Side LO" is greater
than three volts, (DTC B1024).
- The voltage measured at "Driver Side LO" and "Passenger
Side LO" are less than three volts.
- Crash data recording reserved voltage discharge time failure for three
consecutive ignition cycles.
- The calculated checksum for internal memory does not match the store value.
- The sensing device inside the SDM which converts vehicle velocity changes
to an electrical signal is malfunctioning.
- The driver current source and/or passenger current source is malfunctioning.
- The temporary memory storage area is malfunctioning.
- The SDM is unable to read from or write to EEPROM.
- The voltage measured at "Driver Side LO" and "Passenger
Side LO" are greater than or equal to five volts. This indicates that an internal
arming sensor is shorted.
- There is a Micro Processor energy reserve time failure.
Conditions for Setting the DTC
Any of the indicated malfunctions are detected by the SDM. The malfunctions
are tested at different times:
- "Turn-On" and "Continuous Monitoring
- "Turn-On"
- "Continuous Monitoring"
- "Current Source Diagnostics"
- Asynchronously
Action Taken When the DTC Sets
The SDM turns on the AIR BAG telltale lamp and sets DTC B1071. DTC B1071 may
or may not be latched with DTC B1018 or DTC B1024.
Conditions for Clearing the DTC
The malfunction is no longer occurring and the ignition switch is turned OFF,
or a scan tool "Clear Codes" command is issued. Some of the indicated
malfunctions will only allow the AIR BAG telltale lamp to go out briefly then come
back ON. The SDM must be replaced.
Diagnostic Aids
When DTC B1071 is latched with DTC B1018 or B1024, it is critical to diagnose
those DTCs before replacing the SDM. If DTC B1071 returns after the SDM has been replaced,
make sure that "Driver Side LO" and "Passenger Side LO" are
not less than three volts.
Caution
Be careful when you handle a sensing and diagnostic module (SDM). Do not strike
or jolt the SDM. Before applying power to the SDM:
- Remove any dirt, grease, etc. From the mounting surface.
- Position the SDM horizontally on the mounting surface.
- Tighten all of the SDM fasteners and SDM bracket fasteners to the specified
torque value.
Failure to follow the correct procedures could cause air bag deployment, personal
injury, or unnecessary SIR system repairs.
Step
| Action
| Yes
| No
|
1
| Did you perform the SIR Diagnostic System Check?
| Go to
Step 2
| Go to
SIR Diagnostic System Check
|
2
| Is DTC B1018 also set?
| Go to
Step 3
| Go to
Step 4
|
3
| Go to DTC B1018.
| --
| --
|
4
| Is DTC B1024 also set?
| Go to
Step 5
| Go to
Step 6
|
5
| Go to DTC B1024.
| --
| --
|
6
|
- Turn the ignition switch OFF.
- Replace the SDM. Refer to "Sensing and Diagnostic Module (SDM)"
in this service manual.
- Repeat the SIR Diagnostic System Check.
| --
| --
|
Important
Always replace any SDM with DTC B1071 after
repairing all other DTCs.