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Seat Belt Systems




Air Bag and Safety Belt Pretensioner Supplemental Restraint System (SRS)

Pinpoint Test AB: DTCs U0028:08 and U0028:88

Refer to Wiring Diagram Set 42, Vehicle Dynamic Systems for schematic and connector information Electrical Diagrams.

Normal Operation

The Restraints Control Module (RCM) supplies the stability/traction control system with the yaw rate, roll rate, lateral and longitudinal accelerometer over a dedicated Controller Area Network (CAN). If the RCM (Restraints Control Module) detects a fault with communications with the ABS module or dedicated CAN (Controller Area Network) circuits, it sets DTC U0028:08 or U0028:88.

The RCM (Restraints Control Module) does not request the Instrument Panel Cluster (IPC) to illuminate the air bag warning indicator if either DTC U0028:08 or U0028:88 is set.

- DTC U0028:08 (Vehicle Communication Bus A: Bus Signal / Message Failures)- A fault is indicated when the RCM (Restraints Control Module) does not receive dedicated CAN (Controller Area Network) messages from the ABS module for 5 seconds. An open dedicated CAN (Controller Area Network) circuit, incorrectly installed ABS module or loss of power and/or ground to the ABS module can set this DTC.

- DTC U0028:88 (Vehicle Communication Bus A: Bus Off)- A fault is indicated when the RCM (Restraints Control Module) detects the dedicated CAN (Controller Area Network) circuits are shorted to ground, shorted to voltage or shorted to each other.

This pinpoint test is intended to diagnose the following:

- Wiring, terminals or connectors

- RCM (Restraints Control Module)

- ABS module

PINPOINT TEST AB : DTCs U0028:08 AND U0028:88

WARNING: Never probe the electrical connectors on air bag, Safety Canopy(R) or side air curtain modules. Failure to follow this instruction may result in the accidental deployment of these modules, which increases the risk of serious personal injury or death.

WARNING: Do not handle, move or change the original horizontal mounting position of the restraints control module (RCM) while the RCM is connected and the ignition switch is ON. Failure to follow this instruction may result in the accidental deployment of the Safety Canopy(R) and cause serious personal injury or death.

WARNING: Never disassemble or tamper with safety belt buckle/retractor pretensioners, adaptive load limiting retractors, safety belt inflators, or probe the electrical connectors. Failure to follow this instruction may result in the accidental deployment of the safety belt pretensioners, adaptive load limiting retractors, or safety belt inflators, which increases the risk of serious personal injury or death.

NOTICE: Use the correct probe adapter(s) from the Flex Probe Kit when taking measurements. Failure to use the correct probe adapter(s) may damage the connector.


Most faults are due to connector and/or wiring concerns. Carry out a thorough inspection and verification before proceeding with the pinpoint test. Inspection and Verification

NOTE: Most faults are due to connector and/or wiring concerns. Carry out a thorough inspection and verification before proceeding with the pinpoint test. Inspection and Verification

NOTE: Only disconnect or reconnect Supplemental Restraint System (SRS) components when instructed to do so within a pinpoint test step. Failure to follow this instruction may result in incorrect diagnosis of the SRS (Supplemental Restraint System).

NOTE: Always make sure the correct SRS (Supplemental Restraint System) component is being installed. Parts released for other vehicles may not be compatible even if they appear physically similar.
Check the part number listed in the parts catalog to make sure the correct component is being installed. If an incorrect SRS (Supplemental Restraint System) component is installed, DTCs may set.

NOTE: The SRS (Supplemental Restraint System) must be fully operational and free of faults before releasing the vehicle to the customer.

AB1 RETRIEVE RCM (Restraints Control Module) DTCs

- Ignition ON.

- Enter the following diagnostic mode on the scan tool: Self Test- RCM (Restraints Control Module).

Was DTC U0028:08 or U0028:88 retrieved on-demand during self-test?

Yes
This fault cannot be cleared until it is corrected and the DTC is no longer retrieved on-demand during self-test.

For DTC U0028:08, GO to AB2.

For DTC U0028:88, GO to AB6.

No
This is an intermittent fault when present as a Continuous Memory Diagnostic Trouble Code (CMDTC) only. GO to AB13.

AB2 VERIFY THE RCM (Restraints Control Module) PART NUMBER

- Enter the following diagnostic mode on the scan tool: Log Viewer.

- Retrieve and record the RCM (Restraints Control Module) part number from Log Viewer.

- Check the part number recorded against the number listed in the parts catalog.

Is the correct RCM (Restraints Control Module) installed in the vehicle?

Yes
GO to AB3.

No
INSTALL the correct RCM (Restraints Control Module). REFER to Restraints Control Module (RCM) . GO to AB14.

AB3 VERIFY THE ABS MODULE PART NUMBER

- Retrieve and record the ABS module part number from Log Viewer.

- Check the part number recorded against the part number listed in the parts catalog.

Is the correct ABS module installed in the vehicle?

Yes
GO to AB4.

No
INSTALL the correct ABS module. GO to AB14.

AB4 CHECK THE HS-CAN (High Speed Controller Area Network) COMMUNICATIONS (ABS MODULE COMMUNICATIONS)

- Ignition ON.

- Enter the following diagnostic mode on the scan tool: Network Test.

NOTE: The Network Test does not test the dedicated CAN (Controller Area Network) communications between the ABS module and RCM (Restraints Control Module).


Did the Network Test pass (ABS module communicates with the scan tool)?

Yes
GO to AB5.

No
REFER to Information Bus to diagnose the High Speed Controller Area Network (HS-CAN) /ABS module communication concern.
GO to AB14.

AB5 CHECK THE DEDICATED CAN (Controller Area Network) CIRCUITS FOR AN OPEN

- Ignition OFF.

- Depower the SRS (Supplemental Restraint System). Refer to Supplemental Restraint System (SRS) Depowering and Repowering Supplemental Restraint System (SRS) Depowering and Repowering.

- Disconnect: RCM (Restraints Control Module) C310A and C310B.

- Disconnect: ABS Module C135.

- Measure the resistance between the ABS module C135, harness side and the RCM (Restraints Control Module) C310B, harness side as indicated in the following chart:

ABS Module Circuit RCM (Restraints Control Module) C135-18 VCA23 (BU/WH) C310B-20 C135-19 VCA24 (GN/OG) C310B-19






Are the resistances less than 5 ohms?

Yes
GO to AB9.

No
REPAIR circuits VCA24 (GN/OG) and VCA23 (BU/WH).

Refer to Wiring Diagram Set 5 for schematic and connector information Electrical Diagrams.
GO to AB14.

AB6 CHECK THE DEDICATED CAN (Controller Area Network) CIRCUITS FOR A SHORT TO VOLTAGE

- Ignition OFF.

- Depower the SRS (Supplemental Restraint System). Refer to Supplemental Restraint System (SRS) Depowering and Repowering Supplemental Restraint System (SRS) Depowering and Repowering.

- Disconnect: RCM (Restraints Control Module) C310A and C310B.

- Disconnect: ABS Module C135.

- Repower the SRS (Supplemental Restraint System). Refer to Supplemental Restraint System (SRS) Depowering and Repowering Supplemental Restraint System (SRS) Depowering and Repowering.

- Ignition ON.

- Measure the voltage between ground and:
- ABS module C135-18, circuit VCA23 (BU/WH), harness side.

- ABS module C135-19, circuit VCA24 (GN/OG), harness side.







Is any voltage present?

Yes
REPAIR circuit VCA24 (GN/OG) or VCA23 (BU/WH).

Refer to Wiring Diagram Set 5 for schematic and connector information Electrical Diagrams.
GO to AB14.

No
GO to AB7.

AB7 CHECK THE DEDICATED CAN (Controller Area Network) CIRCUITS FOR A SHORT TO GROUND

- Ignition OFF.

- Measure the resistance between ground and:
- ABS module C135-18, circuit VCA23 (BU/WH), harness side.

- ABS module C135-19, circuit VCA24 (GN/OG), harness side.







Are the resistances greater than 10,000 ohms?

Yes
GO to AB8.

No
REPAIR circuit VCA24 (GN/OG) or VCA23 (BU/WH).

Refer to Wiring Diagram Set 5 for schematic and connector information Electrical Diagrams.
GO to AB14.

AB8 CHECK FOR SHORT BETWEEN THE DEDICATED CAN (Controller Area Network) CIRCUITS

- Measure the resistance between ABS module C135-18, circuit VCA23 (BU/WH), harness side and C135-19, circuit VCA24 (GN/OG), harness side.






Is the resistance greater than 10,000 ohms?

Yes
GO to AB9.

No
REPAIR circuits VCA24 (GN/OG) and VCA23 (BU/WH).

Refer to Wiring Diagram Set 5 for schematic and connector information Electrical Diagrams.
GO to AB14.

AB9 CHECK THE RCM (Restraints Control Module) TERMINATING RESISTOR

- Connect: RCM (Restraints Control Module) C310B.

- Measure the resistance between ABS module C135-18, circuit VCA23 (BU/WH), harness side and C135-19, circuit VCA24 (GN/OG), harness side.






Is the resistance between 108 and 132 ohms?

Yes
GO to AB10.

No
GO to AB11.

AB10 CHECK THE ABS MODULE TERMINATING RESISTOR

- Disconnect: RCM (Restraints Control Module) C310B.

- Connect: ABS Module C135.

- Measure the resistance between RCM (Restraints Control Module) C310B-20, circuit VCA23 (BU/WH), harness side and C310B-19, circuit VCA24 (GN/OG), harness side.






Is the resistance between 108 and 132 ohms?

Yes
For DTC U0028:08, GO to AB11.

For DTC U0028:88, GO to AB12.

No
GO to AB12.

AB11 CONFIRM THE RCM (Restraints Control Module) FAULT

NOTE: Make sure all restraint system components, sensor electrical connectors and the RCM (Restraints Control Module) electrical connectors are connected before carrying out self-test. If not, DTCs will be recorded.

- If previously directed to repower the SRS (Supplemental Restraint System), depower the SRS (Supplemental Restraint System). Refer to Supplemental Restraint System (SRS) Depowering and Repowering Supplemental Restraint System (SRS) Depowering and Repowering.

- Prior to reconnecting any previously disconnected SRS (Supplemental Restraint System) component:
- inspect connector(s) (including any in-line connectors) for pushed-out, loose or spread terminals and loose or frayed wire connections at terminals.

- inspect wire harness for any damage, pinched, cut or pierced wires.

- inspect RCM (Restraints Control Module) C310A and C310BConnector Position Assurance (CPA) lever/lock for correct operation. Refer to Restraints Control Module (RCM) .

- inspect ABS module C135 for dirt, corrosion, water intrusion, pushed-out, loose or spread terminals and loose or frayed wire connections at terminals.

- repair any concerns found.
Refer to Wiring Diagram Set 5, Connector Repair Procedures for schematic and connector information Electrical Diagrams.

- Connect: All Previously Disconnected Component(s)/Connector(s).

- Repower the SRS (Supplemental Restraint System). Do not prove out the SRS (Supplemental Restraint System) at this time. Refer to Supplemental Restraint System (SRS) Depowering and Repowering Supplemental Restraint System (SRS) Depowering and Repowering.

- Ignition ON.

- Enter the following diagnostic mode on the scan tool: Self Test- RCM (Restraints Control Module).

Was DTC U0028:08 retrieved on-demand during self-test?

Yes
INSTALL a new RCM (Restraints Control Module). REFER to Restraints Control Module (RCM) . GO to AB14.

No
In the process of diagnosing the fault, the fault condition has become intermittent.

Do not install any new SRS (Supplemental Restraint System) components at this time. Install SRS (Supplemental Restraint System) components only when directed to do so in the pinpoint test.GO to AB13.

AB12 CONFIRM THE ABS MODULE FAULT

NOTE: Make sure all restraint system components and the RCM (Restraints Control Module) electrical connectors are connected before carrying out self-test. If not, DTCs will be recorded.

- If previously directed to repower the SRS (Supplemental Restraint System), depower the SRS (Supplemental Restraint System). Refer to Supplemental Restraint System (SRS) Depowering and Repowering Supplemental Restraint System (SRS) Depowering and Repowering.

- Prior to reconnecting any previously disconnected SRS (Supplemental Restraint System) component:
- inspect connector(s) (including any in-line connectors) for pushed-out, loose or spread terminals and loose or frayed wire connections at terminals.

- inspect wire harness for any damage, pinched, cut or pierced wires.

- inspect RCM (Restraints Control Module) C310A and C310B CPA (Connector Position Assurance) lever/lock for correct operation. Refer to Restraints Control Module (RCM) .

- inspect ABS module C135 for dirt, corrosion, water intrusion, pushed-out, loose or spread terminals and loose or frayed wire connections at terminals.

- repair any concerns found.
Refer to Wiring Diagram Set 5, Connector Repair Procedures for schematic and connector information Electrical Diagrams.

- Connect: All Previously Disconnected Component(s)/Connector(s).

- Repower the SRS (Supplemental Restraint System). Do not prove out the SRS (Supplemental Restraint System) at this time. Refer to Supplemental Restraint System (SRS) Depowering and Repowering Supplemental Restraint System (SRS) Depowering and Repowering.

- Ignition ON.

- Enter the following diagnostic mode on the scan tool: Self Test- RCM (Restraints Control Module).

Was DTC U0028:88 retrieved on-demand during self-test?

Yes
INSTALL a new ABS module. GO to AB14.

No
In the process of diagnosing the fault, the fault condition has become intermittent.

Do not install any new SRS (Supplemental Restraint System) components at this time. Install SRS (Supplemental Restraint System) components only when directed to do so in the pinpoint test.GO to AB13.

AB13 CHECK FOR AN INTERMITTENT FAULT

- Ignition OFF.

- Depower the SRS (Supplemental Restraint System). Refer to Supplemental Restraint System (SRS) Depowering and Repowering Supplemental Restraint System (SRS) Depowering and Repowering.

- Disconnect: RCM (Restraints Control Module) C310B.

- Disconnect: ABS Module C135.
- inspect connector(s) (including any in-line connectors) for corrosion, loose or spread terminals and loose or frayed wire connections at terminals.
- inspect wire harness for any damage, pinched, cut or pierced wires.
- repair any concerns found.
Refer to Wiring Diagram Set 5, Connector Repair Procedures for schematic and connector information Electrical Diagrams.

- Connect: All Previously Disconnected Component(s)/Connector(s).

- Repower the SRS (Supplemental Restraint System). Do not prove out the SRS (Supplemental Restraint System) at this time. Refer to Supplemental Restraint System (SRS) Depowering and Repowering Supplemental Restraint System (SRS) Depowering and Repowering.

- Ignition ON.

- Enter the following diagnostic mode on the scan tool: Self Test- RCM (Restraints Control Module).

Was DTC U0028:08 or U0028:88 retrieved on-demand during self-test?

Yes
This fault cannot be cleared until it is corrected and the DTC is no longer retrieved on-demand during self-test.

CHECK for causes of the intermittent fault in the areas previously worked in, particularly the pins and terminals of any electrical connector that were disconnected. REPAIR any intermittent wiring, terminal or connector concerns found.

Refer to Wiring Diagram Set 5, Connector Repair Procedures for schematic and connector information Electrical Diagrams.

GO to AB14.

No
The fault is not present and cannot be recreated at this time. Do not install any new SRS (Supplemental Restraint System) components at this time. Install SRS (Supplemental Restraint System) components only when directed to do so in the pinpoint test.GO to AB14.

AB14 CHECK FOR ADDITIONAL RCM (Restraints Control Module) AND ABS MODULE DTCs

- Ignition OFF.

WARNING: Turn the ignition OFF and wait one minute to deplete the backup power supply. Failure to follow this instruction may result in serious personal injury or death in the event of an accidental deployment.

- Reconnect all SRS (Supplemental Restraint System) components (if previously disconnected).

- If previously directed to depower the SRS (Supplemental Restraint System), repower the SRS (Supplemental Restraint System). Do not prove out the SRS (Supplemental Restraint System) at this time. Refer to Supplemental Restraint System (SRS) Depowering and Repowering Supplemental Restraint System (SRS) Depowering and Repowering.

- Ignition ON.

- Enter the following diagnostic mode on the scan tool: Self Test- RCM (Restraints Control Module).

- Enter the following diagnostic mode on the scan tool: Self Test- ABS Module.

Were any DTCs retrieved from the RCM (Restraints Control Module) or ABS module during self-test?

Yes
Do not clear any DTCs until all DTCs have been resolved. GO to the appropriate DTC Chart and/or Antilock Brakes / Traction Control Systems for pinpoint test direction Air Bag Systems.

No
CLEAR all CMDTCs (Continuous Memory Diagnostic Trouble Codes). PROVE OUT the SRS (Supplemental Restraint System). The repair is complete.
RETURN the vehicle to the customer.

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