B0091
Document ID: 2000251DTC B0091
Diagnostic Instructions
• Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle
• Review Strategy Based Diagnosis Strategy Based Diagnosis
• Diagnostic Procedure Instructions Diagnostic Procedure Instructions
DTC Descriptors
DTC B0091 00: Center Front Impact Sensor Malfunction
DTC B0091 0F: Center Front Impact Sensor Erratic
DTC B0091 39: Center Front Impact Sensor Internal Electronic Failure
DTC B0091 3A: Center Front Impact Sensor Incorrect Component Installed
Diagnostic Fault Information
Circuit
Center Front Impact Sensor High Signal
Short to Ground B0091 00
High Resistance B0091 OF
Open B009100
Short to Voltage B0091 00
Signal Performance B0091 39
Center Front Impact Sensor Low Reference
Short to Ground B0091 00
High Resistance B0091 0F
Open B009100
Short to Voltage B0091 00
Signal Performance B0091 39
Circuit/System Description
The impact sensors are equipped on vehicles to supplement the Supplemental Inflatable Restraint (SIR) System performance. The impact sensors are electronic and are not part of the deployment loops, but instead provide inputs to the inflatable restraint sensing and diagnostic module (SDM). The impact sensors can assist in determining the severity of some frontal and side collisions. The SDM uses the input from the impact sensors to assist in determining the severity of a collision further supporting air bag deployment. If the SDM determines a deployment is warranted, the SDM will cause current to flow through the deployment loops deploying the appropriate air bags. The center front impact sensor and side impact sensors utilize a bidirectional 2-wire circuit. The sensors modulate current on the interface to send identification, state of health, and deployment commands to the inflatable restraint sensing and diagnostic module (SDM). The SDM serves as a power source and a ground for the sensors. When the ignition is turned ON and input power from the SDM is first detected, the sensors respond by performing internal diagnostics and sending an identification to the SDM. The SDM considers the identification to be valid if the response time is less than 5 seconds. The sensors continually communicate status messages to the SDM, which determines if a fault is present in the sensor circuit. When a fault is detected, the SDM may reset the sensors up to 2 times by removing and reapplying power to it. If the fault is still present, the SDM will set a DTC.
Conditions for Running the DTC
Ignition voltage is between 9-16 Volts.
Conditions for Setting the DTC
B0091 00
• The front impact sensor has been an open, been shorted to ground, or been shorted to voltage.
• The center front impact sensor current is greater than 23 mA for greater than 5 milliseconds.
B0091 0F
The SDM has received erratic messages from the center front impact sensor.
B0091 39
• The SDM has received a Not OK (NOK) message from the center front impact sensor.
• The SDM has not received a message.
B0091 3A
• The SDM has received identification message from the center front impact sensor which does not match the identification stored in the SDM memory.
• The SDM has reset the center front impact sensor twice without detecting the correct identification message.
Action Taken When the DTC Sets
• The SDM requests the instrument panel cluster to illuminate the AIR BAG indicator.
• The SIR system is disabled and no deployments are allowed.
Conditions for Clearing the DTC
• The condition for setting the DTC no longer exists.
• A history DTC will clear once 100 malfunction-free ignition cycles have occurred.
Reference Information
Schematic Reference
SIR Schematics [1][2]Air Bag Systems
Connector End View Reference
Component Connector End Views Connector Views
Description and Operation
SIR System Description and Operation Description and Operation
Electrical Information Reference
• Circuit Testing Circuit Testing
• Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs Wiring Repairs
• Connector Repairs Connector Repairs
Scan Tool Reference
Control Module References Control Module References
Circuit/System Verification
1. For DTC B0091 39 or B0091 3A replace the the B59 center front impact sensor.
2. For DTC B0091 00 or B0091 0F perform the Circuit/System Testing.
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the K36 SDM.
2. Test for infinite resistance between the signal circuit terminal 38 and ground.
--> If not the specified value, test the signal circuit for a short to ground.
3. Ignition ON, test for less than 1V between the signal circuit terminal 38 and ground.
--> If greater than the specified range, test the signal circuit for a short to voltage.
4. Ignition OFF, test for infinite resistance between the low reference circuit terminal 36 and ground.
--> If not the specified value, test the low reference circuit for a short to ground.
5. Ignition ON, test for less than 1V between the low reference circuit terminal 36 and ground.
--> If greater than the specified range, test the low reference circuit for a short to voltage.
6. Test for 1.8-5.5 ohms between signal circuit terminal 38 and low reference circuit terminal 36
--> If less than the specified range, replace the B59 center front impact sensor
--> If greater than the specified range, test the signal circuit and low reference circuit for an open/high resistance. If the circuits test normal, replace the B59 center front impact sensor
7. If all circuits test normal, replace the K36 SDM.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests
• SIR/SRS Wiring Repairs SIR/SRS Wiring Repairs
• Inflatable Restraint Front End Sensor Replacement Inflatable Restraint Front End Sensor Replacement
• Control Module References Control Module References