B0074
DTC B0074
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview)provides an overview of each diagnostic category.
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 pressure sensor signal is less than 0.05 volt or greater than 4.5 volts for 500 milliseconds.
* The PPS detects the voltage at the pressure sensor voltage 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 25mA or greater for 500 milliseconds.
Action Taken When the DTC Sets
* The SDM disables the I/P module deployment loop.
* The SDM will illuminate the air bag status OFF indicator.
* The SDM will illuminate the AIR BAG warning lamp.
Conditions for Clearing the DTC
* The condition responsible for setting the DTC no longer exists.
* A history DTC will clear once 255 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 (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)
Scan Tool Reference
Control Module References (Programming and Relearning)for scan tool information
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 module
* The PPS pressure sensor wiring harness connector
* The PPS module wiring harness connector
1. Ignition OFF, disconnect the harness connector at the PPS.
2. Test for less then 10 ohms between the ground circuit terminal D and ground.
• If greater then the specified range, test the circuit for an open/high resistance.
3. Ignition ON, verify a test lamp illuminates between the B+ circuit terminal A and ground.
• If the test lamp does not illuminate, test the circuit for a short to ground or an open/high resistance. if circuit tests normal, replace the PPS.
4. Reconnect all PPS components and perform the Passenger Presence System Rezeroing (Programming and Relearning) procedure.
5. Clear all DTCs and operate the vehicle within the conditions for running the DTC. DTC B0074 should not set.
• If the DTC sets, replace the PPS.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* SIR/SRS Wiring Repairs (Component Tests and General Diagnostics)
* Control Module References (Programming and Relearning)for PPS replacement, setup, and programming