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
Diagnostic Fault Information
Circuit
| Short to Ground
| High Resistance
| Open
| Short to Voltage
|
Pressure Sensor Low Reference
| --
| B0074 03
| B0074 03
| --
|
Pressure Sensor Signal
| B0074 07
| B0074 03, 07
| B0074 03, 07
| B0074 03
|
Pressure Sensor Voltage Reference
| B0074 07
| B0074 07
| B0074 07
| B0074 03
|
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 illuminating 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 illuminate the AIR BAG indicator.
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 0.5 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. |
• | The SDM disables the I/P module deployment loop. |
• | The PPS will illuminate the passenger air bag status OFF indicator. |
• | The SDM requests the instrument panel cluster (IPC) to illuminate the AIR BAG indicator. |
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
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Testing
Important:
• | The PPS pressure sensor is not serviced separately. The PPS replacement with the PPS pressure sensor must be serviced as a complete unit. |
• | When removing connectors, inspect for damage or corrosion. Damage or corrosion in the following requires repair or replacement of the affected component/connector: |
• | PPS pressure sensor wiring harness connector |
• | PPS module wiring harness connector |
- Ignition OFF, disconnect the harness connector at the PPS pressure sensor and inspect the component and harness sides for damage or corrosion.
⇒ | If damage or corrosion is found, repair or replace as necessary. |
- Ignition ON, test for 4.5-5.5 volts between the voltage reference circuit terminal A and ground.
⇒ | If less that the specified range, test the voltage reference circuit for open/high resistance or a short to ground. If the circuit tests normal, replace the PPS. |
⇒ | If greater that the specified range, test the voltage reference circuit for a short to voltage. If the circuit tests normal, replace the PPS. |
Important: The AIR BAG BATT Fuse that supplies B+ voltage must be removed to ensure the PPS module is inactive. An active PPS module may cause inaccurate resistance readings.
- Ignition OFF, remove the AIR BAG BATT Fuse. Test for less than 2.0 ohms between low reference terminal C and ground.
⇒ | If greater than the specified range, test the low reference circuit for open/high resistance. If the circuit tests normal, replace the PPS. |
- Ignition OFF, disconnect the harness connector at the PPS module.
- Test for infinite resistance between the signal circuit terminal B and ground.
⇒ | If less than the specified value, test the signal circuit for a short to ground. |
- Ignition ON, test for less than 1 volt between the signal circuit terminal B and ground.
⇒ | If greater than the specified range, test the signal circuit for a short to voltage. |
- Test for less than 1 ohm between the PPS sensor signal circuit terminal B and the PPS module terminal 6.
⇒ | If greater than the specified range, test the signal circuit for open/high resistance. If the circuit tests normal, replace the PPS. |
- If all circuits test normal, replace the PPS which includes the pressure sensor.
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic procedure.