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U0172






U0172-LOST COMMUNICATION W/LEFT SIDE SATELLITE ACCELERATION SENSOR 1





For a complete wiring diagram, refer to the Wiring Information Electrical Diagrams.

Theory of Operation

The impact sensors perform their own self-test using power supplied by the Occupant Restraint Controller (ORC) then communicates this status back to the ORC with periodic updates. The repair of this fault condition involves verifying the integrity of the wiring between the ORC and the sensor.

- When Monitored:
The ORC continuously communicates with the Left Side Impact Sensor 1 over the sensor signal circuit. The sensor communication and on-board diagnostics are powered by the ORC signal.

- Set Condition:
This Diagnostic Trouble Code (DTC) set, if the ORC and the Left Side Impact Sensor 1 do not establish and maintain valid data communications.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Restraints System Pre-Diagnostic Procedure.

1. VERIFY DTC U0172-LOST COMMUNICATION W/LEFT SIDE SATELLITE ACCELERATION SENSOR 1 IS ACTIVE

NOTE: Make sure the battery is fully charged.

1. Turn the ignition on.
2. With the scan tool, read the ORC DTCs.

Does the scan tool display active DTC U0172-LOST COMMUNICATION W/LEFT SIDE IMPACT SENSOR 1?

Yes

- Go To 2

No

- Perform the RESTRAINT SYSTEM INTERMITTENT TEST. Restraints System Intermittent Condition Test

2. CHECK THE (R13, R15) LEFT SIDE IMPACT SENSOR 1 SIGNAL AND GROUND CIRCUITS FOR A SHORT TO BATTERY





WARNING: Turn the ignition off, disconnect the 12-volt battery and wait two minutes before proceeding. Failure to follow these instructions may result in possible serious or fatal injury.

1. Disconnect the Left Side Impact Sensor 1 harness connector.
2. Disconnect the ORC harness connectors.

NOTE: Check connectors - Clean and repair as necessary.

WARNING: Turn the ignition on, then reconnect the 12-volt battery. Failure to follow these instructions may result in possible serious or fatal injury.

3. Measure the voltage of the (R13) Left Side Impact Sensor 1 Signal circuit cavity 1 between the Left Side Impact Sensor 1 harness connector and ground.
4. Measure the voltage of the (R15) Left Side Impact Sensor 1 Ground circuit cavity 2 between the Left Side Impact Sensor 1 harness connector and ground.

Is there any voltage present?

Yes

- Repair the (R13, R15) Left Side Impact Sensor 1 circuits for a short to battery.
- Perform the RESTRAINT SYSTEM VERIFICATION TEST. Restraints System Verification Test.

No

- Go To 3

3. CHECK THE (R13) LEFT SIDE IMPACT SENSOR 1 SIGNAL CIRCUIT FOR A SHORT TO GROUND





WARNING: Turn the ignition off, disconnect the 12-volt battery and wait two minutes before proceeding. Failure to follow these instructions may result in possible serious or fatal injury.

1. Measure the resistance of the (R13) Left Side Impact Sensor 1 Signal circuit between the Left Side Impact Sensor 1 harness connector and ground.

Is the resistance below 100K Ohms?

Yes

- Repair the (R13) Left Side Impact Sensor 1 Signal circuit for a short to ground.
- Perform the RESTRAINT SYSTEM VERIFICATION TEST. Restraints System Verification Test.

No

- Go To 4

4. CHECK THE (R13, R15) LEFT SIDE IMPACT SENSOR CIRCUITS FOR A SHORT TOGETHER




1. Measure the resistance between the (R13) Left Side Impact Sensor 1 Signal cavity 1 and (R15) Left Side Impact Sensor 1 Ground circuits cavity 2 in the Left Side Impact Sensor 1 harness connector.

Is the resistance below 100K Ohms?

Yes

- Repair the (R13, R15) Left Side Impact Sensor 1 circuits shorted together.
- Perform the RESTRAINT SYSTEM VERIFICATION TEST. Restraints System Verification Test.

No

- Go To 5

5. CHECK THE (R15) LEFT SIDE IMPACT SENSOR 1 GROUND CIRCUIT FOR AN OPEN OR HIGH RESISTANCE




1. Connect the SRS Load Tool Adaptor 8443-25 to the ORC harness connectors.
2. Measure the resistance of the (R15) Left Side Impact Sensor 1 Ground circuit between the Left Side Impact Sensor 1 harness connector and SRS Load Tool Adaptor 8443-25 32 way cavity 29.

Is the resistance below 1 ohm?

Yes

- Go To 6

No

- Repair the (R15) Left Side Impact Sensor 1 Ground circuit for an open or high resistance.
- Perform the RESTRAINT SYSTEM VERIFICATION TEST. Restraints System Verification Test.

6. CHECK THE (R13) LEFT SIDE IMPACT SENSOR 1 CIRCUIT FOR AN OPEN OR HIGH RESISTANCE




1. Measure the resistance of the (R13) Left Side Impact Sensor 1 Signal circuit between the Left Side Impact Sensor 1 harness connector and the SRS Load Tool Adaptor 8443-25 32 way cavity 30.

Is the resistance below 1 ohm?

Yes

- Go To 7

No

- Repair the (R13) Left Side Impact Sensor 1 Signal circuit for an open or high resistance.
- Perform the RESTRAINT SYSTEM VERIFICATION TEST. Restraints System Verification Test.

7. CHECK OPERATION OF THE LEFT SIDE IMPACT SENSOR 1
1. Replace the Left Side Impact Sensor 1.
2. Reconnect the vehicle harness connector to the impact sensor.
3. Remove any special tools or jumper wires and reconnect all previously disconnected components, except the battery.

WARNING: Turn the ignition on, then reconnect the 12-volt battery. Failure to follow these instructions may result in possible serious or fatal injury.

4. Using the most current scan tool software available. Connect the scan tool to the Data Link harness connector.
5. With the scan tool, read and erase the stored DTCs in all airbag system modules.
6. Turn the ignition off, and wait 15 seconds before turning the ignition on.
7. Wait one minute and read active DTCs. If there are none present, read the stored DTCs.

Does the scan tool display active DTC U0172-LOST COMMUNICATION W/LEFT SIDE IMPACT SENSOR 1?

Yes

- WARNING: Turn the ignition off, disconnect the 12-volt battery and wait two minutes before proceeding. Failure to follow these instructions may result in possible serious or fatal injury.

- WARNING: If the Occupant Restraint Controller (ORC) is dropped at any time, it must be replaced. Failure to follow these instructions may result in possible serious or fatal injury.

- Replace the ORC.
- Perform the RESTRAINT SYSTEM VERIFICATION TEST. Restraints System Verification Test.

No

- Repair is complete.
- Perform the RESTRAINT SYSTEM VERIFICATION TEST. Restraints System Verification Test.

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