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Home >> Chevy Truck >> 2013 >> Silverado 3500 4WD V8-6.0L (CNG) >> Repair and Diagnosis >> A L L Diagnostic Trouble Codes ( DTC ) >> Testing and Inspection >> B Code Charts >> B0074

B0074




DTC B0074

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using the diagnostic procedure.

* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.

* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC B0074 03

-
Passenger Presence Sensor Circuit Voltage Below Threshold

DTC B0074 07

-
Passenger Presence Sensor Circuit Voltage Above Threshold

DTC B0074 08

-
Passenger Presence Sensor Circuit Signal Invalid

Diagnostic Fault Information






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 passenger presence sensor. The weight of the occupant sitting in the front passenger seat is measured as a pressure change within the bladder by the passenger presence sensor. The passenger presence 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 in the passenger presence module. When the inflatable restraint sensing and diagnostic module (SDM) detects this DTC within the passenger presence module, 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 passenger presence module will communicate to the SDM through serial data communications that a PPS fault is present. The SDM will then suppress the deployment of the passenger instrument panel air bag 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 passenger presence module detects the voltage at the passenger presence sensor signal is less than 0.5 volt or greater than 4.5 volts for 500 milliseconds.

* The passenger presence module detects the voltage at the passenger presence sensor 5 volt reference is less than 4.5 volts or greater than 9.1 volts for 500 milliseconds.

* The passenger presence module detects the amperage at the passenger presence sensor low reference is 25 mA or greater for 500 milliseconds.

Action Taken When the DTC Sets

* The passenger presence module will set a DTC, and then communicate with the SDM.

* The SDM disables the passenger instrument panel air bag deployment loop.

* The passenger presence module 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.

Diagnostic Aids

* If either the SDM or PPS were replaced verify that the correct part numbers were used for the vehicle application.

* If this DTC is set as either current or history it may have been caused by an electronic device. If an electronic device (Computers, MP3 Players, Cell Phones, Diagnostic Scan Tool, etc.) was placed on the passenger seat the passenger presence module may command the passenger air bag indicator to turn on and/or command the passenger seat belt indicator to turn on. Make sure there are no objects on the passenger seat and clear the DTCs. If this DTC resets then perform this diagnostic. If the DTC does not reset there is no further work needed on the passenger presence system.

* If this DTC is set as either current or history it may have been caused by an aftermarket seat heater. The aftermarket seat heater may command the passenger air bag indicator to turn on and/or command the passenger seat belt indicator to turn on. Remove the aftermarket seat heater from the passenger seat and clear the DTCs. If this DTC resets then perform this diagnostic. If the DTC does not reset there is no further work needed on the passenger presence system.

Reference Information

Electrical Information Reference

* Circuit Testing Circuit Testing

* Connector Repairs Connector Repairs

* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections

* Wiring Repairs Wiring Repairs

Scan Tool Reference

Control Module References Control Module References for scan tool information

Circuit/System Testing

Important:

* The passenger presence sensor is not serviced separately. The PPS replacement with the passenger presence 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:


- Passenger presence sensor


- Passenger presence module


- Passenger presence sensor wiring harness connector


- Passenger presence module wiring harness connector


1. Ignition OFF, disconnect the harness connector at the passenger presence module and inspect the component and harness sides for damage or corrosion.

• If damage or corrosion is found, repair or replace as necessary.

2. Ignition ON, test for 4.5-5.5 volts between the voltage reference circuit terminal 1 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 passenger presence module.

• If greater that the specified range, test the voltage reference circuit for a short to voltage. If the circuit tests normal, replace the passenger presence module.

Important:
The AIR BAG BATT Fuse that supplies B+ voltage must be removed to ensure the passenger presence module is inactive. An active passenger presence module may cause inaccurate resistance readings.


3. Ignition OFF, remove the AIR BAG BATT Fuse. Test for less than 2.0 ohms between low reference terminal 4 and ground.

• If greater than the specified range, test the low reference circuit for open/high resistance. If the circuit tests normal, replace the passenger presence module.

4. Ignition OFF, disconnect the harness connector at the passenger presence module.

5. Test for infinite resistance between the signal circuit terminal 6 and ground.

• If less than the specified value, test the signal circuit for a short to ground.

6. Ignition ON, test for less than 1 volt between the signal circuit terminal 2 and ground.

• If greater than the specified range, test the signal circuit for a short to voltage.

7. If all circuits test normal, replace the passenger presence module.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.

* SIR/SRS Wiring Repairs SIR/SRS Wiring Repairs

* Control Module References Control Module References for passenger presence system replacement, setup, and programming

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