U0172 Lost Communication W/Left Side Satellite Accelaration Sensor 1

 

U0172 code
Wiring U0172 code

Note: This DTC detected in the ORC Module

U0172 code - The location of this left side impact sensor 1 is in the B-pilar Just the first row seating. The impact sensors perform their own self test using power supplied by the Occupant Restraint Controller (ORC. the 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 the setting then the left side impact sensor is to be replaced. A short to voltage fault in the left side impact sensor 1 sensor wiring can cause a loss of comm impact sensor 2 code to set and the possible replacement of a good left side impact sensor 2. 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 2 on the same side to set loss of comm code. The side impact sensors are daisy chained in wiring. So the side impact sensor 1 fault  can cause a loss of comm in the impact sensor 2.

When monitored this DTC the Occupant Restraint Controller (ORC) continously communicate with the left side impact sensor 1 over the sensor signal cirucit. 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 estabilish and maintain valid data communications.

Possible causes U0172 code:

- Signal circuit shorted to battery

- Signal circuit shorted to ground

- Left side impact sensor 1 circuits shorted together

- Left side impact sensor 1 ground circuit open

- Left side impact sensor 1

Diagnostic test U0172 code

Step 1. Verify that DTC U0172 

Turn the ignition off, disconnect the 12V battery and wait two minutes before proceeding. 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.

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

Turn the ignition on, then reconnect the 12V battery and wait two minutes before proceeding. Make sure the battery is fully charged.

Turn the ignition on, with the scan tool read DTC.

Does the scan tool display active B1B72, U0172, U0173 DTC?

Yes, Check for all other internal and lost communication codes indicated in the left side impact sensor daisy chain wiring after diagnosing DTC B1B72, U0172, U0173. Go to step 2

No, Go go step 9.

Step 2. Check The left side impact sensor 1 circuits for a short to battery

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.

Disconnect the Left Side Impact Sensor 1 harness connector. Disconnect the ORC harness connectors. Connect the SRS Load Tool Adaptor 8443-32-L to the ORC harness connectors.

Turn the ignition on, then reconnect the 12-volt battery and wait two minutes before proceeding. Measure the voltage of the Left Side Impact Sensor 1 Signal circuit and the Sensor Ground circuit at the Left Side Impact Sensor 1 harness connector.

Is there any voltage present?

Yes, Turn the ignition off, disconnect the 12- volt battery and wait two minutes before proceeding. Repair the Left Side Impact Sensor 1 circuits for a short to battery.

No, go to step 3

Step 3. Measure the left side impact sensor 1 circuits for a short to ground

Measure the resistance between ground and the Left Side Impact Sensor 1 Signal circuit at the Left Side Impact Sensor 1 harness connector. Measure the resistance between ground 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 Left Side Impact Sensor 1 Signal and Ground circuit for a short to ground.

No, go to step 4.

Step 4. Check the left side impact sensor circuits for a short together

Measure the resistance between the left side impact sensor 1 signal circuit and the sensor ground circuit at the left side impact sensor 1 harness connector.

Is the resistance below 100K Ohms?

Yes, repair the left side impact sensor 1 circuits shorted together.

No, go to step 5.

Step 5. Check the left side impact sensor 1 ground circuit for an open or high resistance

Measure the resistance of the left side impact sensor 1 ground circuit between the left side impact sensor 1 harness connector and the SRS Load tool adaptor 8441-32-L.

Is the resistance below 1 Ohm?

Yes, go to step 6.

No, repair the left side impact sensor 1 ground circuit for an open or high resistance.

Step 6. Check the left side impact sensor 1 circuit for an open or high resistance

Measure the resistance of the left side impact sensor 1 signal circuit between the left impact sensor 1 harness connector and the SRS load tool adaptor 8441-32-L

Is the resistance below 1 Ohm?

Yes, go to step 7.

No, repair the left side impact sensor 1 signal circuit for an open or high resistance.

Step 7. Check operation of the left side impact sensor 1

Replace the Left Side Impact Sensor 1. Reconnect the vehicle body harness to the impact sensor. Remove any special tools or jumper wires and reconnect all previously disconnected components - except the Battery.

Turn the ignition on, then reconnect the 12-volt battery and wait two minutes before proceeding. 

Connect the scan tool to the Data Link Connector - use the most current software available. Use the scan tool and erase the stored codes in all airbag system modules. Turn the Ignition Off, and wait 15 seconds before turning the Ignition On. 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 step 8.

No, repair is complete.

Step 8. Replace the Occupant Restraint Controller

Turn the ignition offm disconnect the 12V battery and wait two minutes before proceeding.

If there are no possible causes remaining, view repair.

Repair, if the Occupant Restraint Controller (ORC) is dropped at any time, it must be replaced. Replace the ORC, perform the Airbag system verification.

Step 9. Test for an intermittent condition


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