Diagnostic Instructions
DTC Descriptors
DTC B0074 03: Passenger Occupant Classification Sensor Circuit Voltage Below Threshold
DTC B0074 07: Passenger Occupant Classification Circuit Voltage Above Threshold
DTC B0074 08: Passenger Occupant Classification Circuit Signal Invalid
Circuit/System Description
The passenger presence system (PPS) uses a silicone filled sensor pad located underneath the passenger seat foam cushion and is connected by a hose clamp to a pressure sensor. The weight of the occupant sitting in the front passenger seat is measured as
a pressure change within the bladder by the pressure sensor. The pressure sensor is a 3-wire sensor consisting of a power, ground, and signal circuit. The PPS continually monitors itself and if a fault in this circuit occurs, a DTC will set. When the sensing
and diagnostic module (SDM) detects this DTC within the PPS, it will notify the customer of the enable/disable status by turning ON the OFF indicator on the PASSENGER AIR BAG ON/OFF indicators. Then the PPS will communicate to the SDM through serial data communications
that a PPS fault is present. The SDM will then suppress the deployment of the instrument panel (I/P) module and then turn the AIR BAG indicator ON.
Conditions for Running the DTC
Ignition voltage is between 9-16 volts.
Conditions for Setting the DTC
• | The PPS detects the voltage at the PPS sensor signal is less than 0.05-volt or greater than 4.5 volts for 500 milliseconds. |
• | The PPS detects the voltage at the PPS sensor 5-volt reference is less than 4.5 volts or greater than 9.1 volts for 500 milliseconds. |
• | The PPS detects the amperage at the PPS sensor low reference is 25 mA or greater for 500 milliseconds. |
Action Taken When the DTC Sets
• | The PPS will set a DTC, and then communicate with the SDM via serial data communications. |
• | The SDM disables the I/P module deployment loop. |
• | The PPS will turn ON the passenger air bag status OFF indicator. |
• | The SDM commands ON the AIR BAG warning lamp via serial data communications. |
Conditions for Clearing the DTC
• | The condition responsible for setting the DTC no longer exists and the scan tool Clear DTCs function is used. |
• | A history DTC will clear once 255 malfunction-free ignition cycles have occurred. |
Reference Information
Electrical Information Reference
Circuit/System Testing
Important: When removing connectors, inspect for damage or corrosion. Damage or corrosion in the following requires repair or replacement of the affected component/connector:
• | The PPS pressure sensor |
• | The PPS pressure sensor wiring harness connector |
• | The PPS module wiring harness connector |
- Ignition OFF, inspect the component and harness sides of the connector for the PPS pressure sensor. Verify there is no damage or corrosion is found.
- Disconnect the PPS module connector.
- Test the PPS sensor signal circuit for a short to ground, a high resistance, or an open. Verify that a short to ground, a high resistance, or an open does not exist.
⇒ | If any of the above conditions are found, make the appropriate repair. |
- Test the PPS sensor low reference circuit for a short to ground, a short to voltage, a high resistance, or an open. Verify that a short to ground, a short to voltage, a high resistance, or an open does not exist.
⇒ | If any of the above conditions are found, make the appropriate repair. |
- Test the PPS sensor 5-volt reference circuit for a short to ground, a short to voltage, a high resistance, or an open. Verify that a short to ground, a short to voltage, a high resistance, or an open does not exist.
⇒ | If any of the above conditions are found, make the appropriate repair. |
- Ignition ON, engine OFF test the PPS sensor signal circuit with a DMM. Measure the voltage of the PPS sensor circuit harness side and ground. The voltage should read 0.05-4.5 volts.
⇒ | If the voltage is more than 5 volts, test the PPS sensor signal circuit for a short to voltage. If the circuit tests good, replace the PPS. |
- Reconnect all PPS components. Use the scan tool to clear all PPS DTCs. Rezero the PPS. Refer to
Passenger Presence System Rezeroing
. Verify DTC B0074 does not exist.
⇒ | If DTC B0074 reset, replace the PPS. |
Repair Instructions
Perform the
Diagnostic Repair Verification
after completing the diagnostic procedure.