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U0172






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

Special Tools:










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

Theory of Operation

The location of this left side impact sensor 1 is in the B-pillar just past the first row seating. Restraints - Description. The impact sensors perform their own self test using power supplied by the Occupant Restraint Controller (ORC) then communicate 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. If the scan tool shows this DTC has a Stored history of setting then the left side impact sensor is to be replaced. A short to voltage fault on the left side impact sensor 1 sensor wiring can cause a loss of comm impact sensor code to set and the possible replacement of a good left side impact sensor. The short to battery fault in a loss of comm or internal circuit failure of the side impact sensor 1 can cause the impact sensor on the same side to set a loss of comm code.

- When Monitored:
The Occupant Restraint Controller (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 code will set, if the ORC and the Left Side Impact Sensor 1 do not establish and maintain valid data communications.





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

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.

NOTE: Using the wiring diagram/schematic as a guide check all related splices and connectors for signs of water intrusion, corrosion, pushed out or bent terminals, and correct pin tension.

NOTE: If after the harness inspection it appears the impact sensor connector is only seated halfway. Reseat the harness connector into the impact sensor and lock the tab.

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

NOTE: Make sure the battery is fully charged.

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

Does the scan tool display active B1B72-LEFT SIDE SATELLITE ACCELERATION SENSOR 1 INTERNAL, U0172-LOST COMMUNICATION W/LEFT SIDE IMPACT SENSOR 1 - DTC?

Yes

- First check and fix DTC B1B72-LEFT SIDE SATELLITE ACCELERATION SENSOR 1 INTERNAL, and DTC U0172-LOST COMMUNICATION W/LEFT SIDE SATELLITE ACCELERATION SENSOR 1.Testing and Inspection. Go To 2

No

- Perform the AIRBAG SYSTEM INTERMITTENT TEST. Initial Inspection and Diagnostic Overview.

2. CHECK THE (R13) AND (R15) LEFT SIDE IMPACT SENSOR 1 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.
3. Connect the SRS Load Tool Adaptor to the ORC C2 harness connector.

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

4. Measure the voltage of the (R13) Left Side Impact Sensor 1 Signal circuit and the (R15) Sensor 1 Ground circuit at the Left Side Impact Sensor 1 connector.

Is there any voltage present?

Yes

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

No

- Go To 3

3. CHECK THE (R13) AND (R15) LEFT SIDE IMPACT SENSOR 1 CIRCUITS FOR A SHORT TO GROUND





WARNING: Turn the ignition on, then reconnect the battery and wait two minutes before proceeding. Failure to follow these instructions may result in possible serious or fatal injury.

1. Measure the resistance between ground and the (R13) Left Side Impact Sensor 1 Signal circuit at the Left Side Impact Sensor 1 harness connector.
2. Measure the resistance between ground and the (R15) Left Side Impact Sensor 1 Ground circuit at the Left Side Impact Sensor 1 harness connector.

Is the resistance below 100K Ohms on either circuit?

Yes

- Repair the (R13) and (R15) Left Side Impact Sensor 1 Signal and Ground circuit for a short to ground.
- Perform the AIRBAG SYSTEM VERIFICATION TEST. Airbag System Verification Test.

No

- Go To 4

4. CHECK THE (R13) AND (R15) LEFT SIDE IMPACT SENSOR 1 CIRCUITS FOR A SHORT TOGETHER




1. Measure the resistance between the (R13) Left Side Impact Sensor 1 Signal circuit and the (R15) Sensor 1 Ground circuit at the Left Side Impact Sensor 1 harness connector.

Is the resistance below 100K Ohms?

Yes

- Repair the (R13) and (R15) Left Side Impact Sensor 1 circuits shorted together.
- Perform the AIRBAG SYSTEM VERIFICATION TEST. Airbag 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. Measure the resistance of the (R15) Left Side Impact Sensor 1 Ground circuit between the Left Side Impact Sensor 1 harness connector and the SRS Load Tool Adaptor.

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 AIRBAG SYSTEM VERIFICATION TEST. Airbag 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.

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 AIRBAG SYSTEM VERIFICATION TEST. Airbag 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 body harness 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 and wait two minutes before proceeding. Failure to follow these instructions may result in possible serious or fatal injury.

4. Connect the scan tool to the Data Link Connector - use the most current software available.
5. Use the scan tool and erase the stored codes 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 codes and if there are none present read the stored codes.

Did the active Left Side Impact Sensor 1 DTC return?

Yes

- Go To 8

No

- Repair is complete.
- Perform the AIRBAG SYSTEM VERIFICATION TEST. Airbag System Verification Test.

8. REPLACE THE OCCUPANT RESTRAINT CONTROLLER

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 airbag control module is dropped at any time, it must be replaced. Failure to take the proper precautions could result in accidental airbag deployment and serious or fatal injury.

If there are no possible causes remaining, view repair.

Repair

- Replace the Occupant Restraint Controller.
- Perform the AIRBAG SYSTEM VERIFICATION TEST. Airbag System Verification Test.

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