PROCEDURE
Note. To check harness for broken wires or short circuits, shake it while holding it or the connector.
| Step | Check | Yes | No |
|---|---|---|---|
| 1 CHECK PRE-INSPECTION. Before performing diagnosis, inspect unit which might influence OnStar (R) problem. < Ref. to INSPECTION . > | Is unit that might influence the problem normal? | Go to step 2 . | Repair or replace each unit. |
| 2 CHECK OnStar(R) LED. Make sure the red LED of OnStar (R) comes on when ignition switch is ON? | Does the red LED come on? | Go to step 3 . | Go to step 4 . |
| 3 CHECK INDICATION OF DIAGNOSTIC TROUBLE CODE (DTC). Calling up the diagnostic trouble code (DTC). < Ref. to OPERATION . > Record all DTCs. Confirm the meaning of DTC using the list of DTC. < Ref. to LIST . > Proceed with the diagnosis corresponding to the diagnostic trouble code (DTC). < Ref. to DIAGNOSTICS CHART WITH TROUBLE CODE . > Confirm repair by activating system. | Is repair work completed? | System is OK. | Go to step 1 . |
| 4 PERFORM DIAGNOSIS ACCORDING TO THE SYMPTOM. Perform diagnostic procedure according to the symptom. < Ref. to DIAGNOSIS FOR EACH SYMPTOM . > Confirm repair by activating system. | Is repair work completed? | System is OK. | Go to step 1 . |
BASIC DIAGNOSTIC PROCEDURE
CAUTION
When the inspection procedure must be performed pressing each OnStar(R) button, call the OnStar(R) call center first.
When VIU and VCU are replaced, contact to the OnStar(R) call center to ask for set-up.
BATTERY
Measure the battery voltage and specific gravity of electrolyte.
Standard voltage: 12 V or more
Specific gravity: Above 1.260
AIRBAG
Inspect that airbag system is normal. Refer to DIAGNOSTIC PROCEDURE , Basic Diagnostic Procedures.
GENERAL PURPOSE TOOLS
| TOOL NAME | REMARKS |
|---|---|
| Circuit Tester | Used for measuring resistance, voltage and ampere. |
GENERAL PURPOSE TOOLS DESCRIPTION
Scheme 25
Scheme 26
Scheme 27
| Contents | Connector No. | Terminal No. | Input/Output signal | |
|---|---|---|---|---|
| Power supply | Power | I73 | 16 | 9 - 16 V |
| Power | I73 | 32 | 9 - 16 V | |
| GND | I73 | 1 | 0 V | |
| GND | I73 | 17 | 0 V | |
| ACC | I73 | 27 | OnStar (R) activates, when the value is greater than 5.5 V | |
| IGN | I73 | 22 | OnStar (R) activates, when the value is greater than 5.5 V | |
| VCU I/O | Audio ground | I72 | 10 | 0 V |
| Audio signal | I72 | 11 | 4.5 V when switch is ON | |
| Audio signal | I72 | 12 | Battery voltage when switch is ON | |
| Microphone GND | I72 | 13 | 0 V when switch is ON | |
| Microphone input signal | I72 | 14 | Signal | |
| Power | I72 | 16 | Battery voltage when switch is ON | |
| 3 wire signal data bus | I72 | 27 | Signal | |
| 3 wire signal data bus | I72 | 28 | Signal | |
| 3 wire signal data bus | I72 | 29 | Signal | |
| Vehicle discrete interface | Door unlock signal | I73 | 12 | At actuation of door unlock Battery voltage |
| Door lock signal | I73 | 29 | At actuation of door lock Battery voltage | |
| Horn signal | I73 | 11 | 0 V at actuation of horn Battery voltage at no actuation of horn | |
| Security signal | I73 | 28 | Signal (5 V) | |
| Headlight signal | I73 | 14 | 0 V at actuation of headlight Battery voltage at no actuation of headlight | |
| Low reference of transceiver | I72 | 30 | 0 V | |
| IGN signal | I72 | 31 | Battery voltage when switch is ON | |
| User interface | Mike signal & power supply | I72 | 25 | Signal |
| Mike return | I72 | 26 | 0 V | |
| Key pad signal | I73 | 4 | 2.14 V at pressing emergency button 1.27 V at pressing OnStar(R) button 1.27 V at pressing call answer/end button | |
| LED Green | I73 | 5 | 3 V when LED illuminates | |
| LED Red | I73 | 25 | 2.5 V when LED illuminates | |
| Key pad low reference | I73 | 20 | 0 V | |
| Key pad power supply | I73 | 6 | Battery voltage | |
| Audio output interface | Audio | I72 | 8 | Signal |
| Audio GND | I73 | 7 | 0 V | |
| TEL ON signal | I72 | 6 | Battery voltage when switch is ON | |
CONNECTOR NO, TERMINAL NO AND INPUT/OUTPUT SIGNAL
Scheme 28
Scheme 29
- Turn ignition switch to OFF.
- Perform the following job steps within 6 seconds.
- Change the ignition switch from ON to OFF 3 times with pressing call answer/end button.
- Turn ignition to ON at the 4th switching action.
- When the call answer/end button is released, LED will blink to indicate DTC. NOTE: Current DTC will be indicated by the red LED. Former DTC will be indicated by the green LED. Current DTC will be indicated first, and then former DTC will be indicated. DTC will be displayed in order of numerical sequence from smallest. DTC will be indicated in 2 times.
LIST
| DTC No. | Content of diagnosis | LED indicator pattern | Index No. |
|---|---|---|---|
| 0 | EEPROM checksum error | No flash | < Ref. to DTC 0 - EEPROM CHECKSUM ERROR . > |
| 1 | GPS signal error | 1 flash | < Ref. to DTC 1 - GPS SIGNAL ERROR . > |
| 2 | Loss of VCU communication with VIU | 2 flashes | < Ref. to DTC 2 - LOSS OF VCU COMMUNICATION WITH VIU . > |
| 3 | SRS Signal fault | 3 flashes | < Ref. to DTC 3 - SRS SIGNAL FAULT . > |
| 4 | Fault communication between GPS and microprocessor | 4 flashes | < Ref. to DTC 4 - GPS MICRO-PROCESSOR COMMUNICATION FAULT . > |
| 5 | Button assembly malfunction | 5 flashes | < Ref. to DTC 5 - BUTTON ASSEMBLY MALFUNCTION . > |
Diagnostic Trouble Code (DTC) CHART
| CAUTION | When DTC 4, which deactivates button module, VIU will not enter to DTC display mode. |
| Content of diagnosis | Index No. |
|---|---|
| One or more OnStar(R) buttons do not operate. | < Ref. to ONE OR MORE OnStar(R) BUTTONS DO NOT OPERATE. . > |
| Contact to OnStar(R) call center is impossible. | < Ref. to CONTACT TO OnStar(R) CALL CENTER IS IMPOSSIBLE. . > |
| OnStar(R) call center cannot setup OnStar(R) system. | < Ref. to ONSTAR(R) CALL CENTER CANNOT SETUP ONSTAR(R) SYSTEM. . > |
| OnStar(R) audio does not operate. | < Ref. to ONSTAR(R) AUDIO DOES NOT OPERATE. . > |
| OnStar(R) button LED does not operate. | < Ref. to ONSTAR(R) LED DOES NOT OPERATE. . > |
DIAGNOSTICS CHART WITH TROUBLE CODE
DEFINITION: OnStar(R) does not operate by pressing button.
Scheme 30
| Step | Check | Yes | No |
|---|---|---|---|
| 1 CHECK BUTTON ASSEMBLY. IMPORTANT: Before pressing button, call OnStar (R) call center to notify the inspection. Turn ignition switch to ON (do not let the engine run). Press each OnStar (R) button. | Does the LED illuminate in green? | Go to step 3. | Go to step 2. |
| 2 CHECK BUTTON. | Does any button malfunction intermittently? | Go to step 7. | Poor contact of connection/Repair poor contact. |
| 3 CHECK HARNESS. Turn ignition switch to OFF. Disconnect VIU connector. Disconnect button assembly connector. Measure resistance between VIU connector and button assembly connector. Connector & Terminal (i73) No. 4 - (i69) No. 1: (i73) No. 6 - 069) No. 3 | Is the measured value less than 0.5 ohm? | Go to step 4. | Repair open harness. |
| 4 CHECK HARNESS. Measure resistance between VIU connector and chassis ground. Connector & Terminal (i73) No. 4 (+) - Chassis ground (-): (i73) No. 6 (+) - Chassis ground (-) | Is the measured value More than 1 Mohm? | Go to step 5. | Repair ground short of harness. |
| 5 CHECK HARNESS. Turn the ignition switch to ON. Measure voltage between VIU connector and chassis ground. Connector & Terminal (i73) No. 4 (+) - Chassis ground (-): (i73) No. 6 (+) - Chassis ground (-) | Is the measured value less than 1 V? | Go to step 6. | Repair battery short of harness. |
| 6 CHECK VOLTAGE OF POWER SUPPLY. Turn ignition switch to OFF. Connect VIU connector. Turn the ignition switch to ON. Measure voltage between button assembly connector and chassis ground. Connector & Terminal (i69) No. 3 (+) - Chassis ground (-) | Is the measured value within 9 to 16 V? | Go to step 7. | REFERENCE: Perform OnStar (R) setup procedure. Replace VIU. < Ref. to REMOVAL , VEHICLE INTERFACE UNIT VIU. > |
| 7 CHECK EMERGENCY BUTTON. Measure resistance between terminals of button assembly. Terminal No. 1 - No. 3 | Is the measured value 3.0 Kohm by pressing emergency button? | Go to step 8. | Replace button assembly. < Ref. to REMOVAL , BUTTON ASSEMBLY. > |
| 8 CHECK OnStar (R) BUTTON. Measure resistance between terminals of button assembly. Terminal No. 1 - No. 3 | Is the measured value 13.0 Kohm. by pressing OnStar (R) button? | Go to step 9. | Replace button assembly. < Ref. to REMOVAL , BUTTON ASSEMBLY. > |
| 9 CHECK CALL ANSWER/END BUTTON. Measure resistance between terminals of button assembly. Terminal No. 1 - No. 3 | Is the measured value 470 ohm by pressing call answer/end button? | Go to step 10. | Replace button assembly. < Ref. to REMOVAL , BUTTON ASSEMBLY. > |
| 10 CHECK POOR CONNECTION OF BUTTON ASSEMBL. Check, if there is any poor contact in harness connector of button assembly. | Was the condition confirmed or repaired? | Go to step 12. | Go to step 11. |
| 11 CHECK IF THERE IS ANY POOR CONTACT IN VIU HARNESS CONNECTOR. | Was the condition confirmed or repaired? | Go to step 12. | Go to step 13. |
| 12 CHECK SYSTEM. Run the system and confirm the result of repair. | Was the trouble repaired? | System is OK. | Go to step 13. |
| 13 CHECK BUTTON ASSEMBLY. Replace button assembly. < Ref. to REMOVAL , BUTTON ASSEMBLY. > Run the system and confirm the result of repair. | Was the trouble repaired? | System is OK. | Go to step 14. |
| 14 CHECK VIU. REFERENCE: Perform OnStar (R) setup procedure. Replace VIU. < Ref. to REMOVAL , VEHICLE INTERFACE UNIT VIU. > Run the system and confirm the result of repair. | Was the trouble repaired? | System is OK. | Go to step 1. |
| IMPORTANT |
|---|
| Before pressing button, call OnStar (R) call center to notify the inspection. |
DIAGNOSTICS CHART WITH TROUBLE CODE
CONTACT TO ONSTAR (R) CALL CENTER IS IMPOSSIBLE.
DEFINITION: When OnStar(R) call button is pressed, audio prompt "Connected to OnStar(R)" or "Impossible to connect to OnStar(R)" will be announced and connection is not performed.
Scheme 31
| Step | Check | Yes | No |
|---|---|---|---|
| 1 CHECK FOR CONNECTION TO OnStar (R) Call Center. Turn ignition to ON (do not let the engine run). Press OnStar (R) button. | Is connection to OnStar (R) call center completed? | Repair temporary poor connection of wiring. | Go to step 2. |
| 2 CHECK OnStar (R) SERIAL DATA RETURN CIRCUIT. Turn ignition switch to OFF. Disconnect connection from vehicle communication unit (VCU). Turn ignition switch to ON (do not let the engine run). Measure resistance between OnStar (R) serial data return circuit and ground. Connector & Terminal (i71) No. 9 (+) - Chassis ground (-) | Is the measured value approx. 5 V? | Go to step 3. | Go to step 6. |
| 3 CHECK OnStar (R) SERIAL DATA (-) CIRCUIT. Measure voltage between OnStar (R) serial data (-) circuit and ground. Connector & Terminal (i71) No. 5 (+) - Chassis ground (-) | Is the measured value approx. 0.17 V? | Go to step 4. | Go to step 9. |
| 4 CHECK CIRCUIT BETWEEN OnStar (R) SERIAL DATA (-) CIRCUIT AND TRANSCEIVER LOW REFERENCE CIRCUIT. Measure voltage between OnStar (R) serial data (-) circuit and transceiver low reference circuit. Connector & Terminal (i71) No. 5 (+) - (i71) No. 3 (-) | Is the measured value approx. 5 V? | Go to step 5. | Go to step 15. |
| 5 CHECK OnStar (R) SERIAL DATA (+) CIRCUIT. Measure voltage between OnStar (R) serial data (+) circuit and ground. Connector & Terminal (i71) No. 4 (+) - Chassis ground (-) | Is the measured value approx. 0.17 V? | Go to step 18. | Go to step 12. |
| 6 CHECK SERIAL DATA RETURN HARNESS. Turn ignition switch to OFF. Disconnect VIU connector. Disconnect VCU connector. Measure resistance between VIU connector and VCU connector. Connector & Terminal (i72) No. 27 - (i71) No. 9 | Is the measured value less than the 0.5 ohm? | Go to step 7. | Repair open harness. |
| 7 CHECK SERIAL DATA RETURN HARNESS. Measure resistance between VIU connector and chassis ground. Connector & Terminal (i72) No. 27 - Chassis ground | Is the measured value More than 1 Mohm? | Go to step 8. | Repair ground short of harness. |
| 8 CHECK SERIAL DATA RETURN HARNESS. Turn the ignition switch to ON. Measure voltage between VIU connector and chassis ground. Connector & Terminal (i72) No. 27 (+) - Chassis ground (-) | Is the measured value less than 1 V? | Go to step 19. | Repair battery short of harness. |
| 9 CHECK HARNESS (-). Turn ignition switch to OFF. Disconnect VIU connector. Disconnect VCU connector. Measure resistance between VIU connector and VCU connector. Connector & Terminal (i72) No. 28 - (i71) No. 5 | Is the measured value less than 0.5 ohm? | Go to step 10. | Repair open harness. |
| 10 CHECK HARNESS (-). Measure resistance between VIU connector and chassis ground. Connector & Terminal (i72) No. 28 - Chassis ground | Is the measured value More than 1 Mohm? | Go to step 11. | Repair ground short of harness. |
| 11 CHECK HARNESS (-). Turn the ignition switch to ON. Measure voltage between VIU connector and chassis ground. Connector & Terminal (i72) No. 28 (+) - Chassis ground (-) | Is the measured value less than 1 V? | Go to step 19. | Repair battery short of harness. |
| 12 CHECK SERIAL DATA (+) HARNESS. Turn ignition switch to OFF. Disconnect VIU connector. Disconnect VCU connector. Measure resistance between VIU connector and VCU connector. Connector & Terminal (i72) No. 29 - (i71) No. 4 | Is the measured value less than 0.5 ohm? | Go to step 13. | Repair open harness. |
| 13 CHECK SERIAL DATA (+) HARNESS. Measure resistance between VIU connector and chassis ground. Connector & Terminal (i72) No. 29 - Chassis ground | Is the measured value More than 1 Mohm? | Go to step 14. | Repair ground short of harness. |
| 14 CHECK SERIAL DATA (+) HARNESS. Turn the ignition switch to ON. Measure voltage between VIU connector and chassis ground. Connector & Terminal (i72) No. 29 (+) - Chassis ground (-) | Is the measured value less than 1 V? | Go to step 19. | Repair battery short of harness. |
| 15 CHECK TRANSCEIVER LOW REFERENCE HARNESS. Turn ignition switch to OFF. Disconnect VIU connector. Disconnect VCU connector. Measure resistance between VIU connector and VCU connector. Connector & Terminal (i72) No. 30 - 071) No. 3 | Is the measured value less than 0.5 ohm? | Go to step 16. | Repair open harness. |
| 16 CHECK TRANSCEIVER LOW REFERENCE HARNESS. Measure resistance between VIU connector and chassis ground. Connector & Terminal (i72) No. 30 - Chassis ground | Is the measured value More than 1 Mohm? | Go to step 17. | Repair ground short of harness. |
| 17 CHECK TRANSCEIVER LOW REFERENCE HARNESS. Turn ignition switch to ON. Measure voltage between VIU connector and chassis ground. Connector & Terminal (i72) No. 30 (+) - Chassis ground (-) | Is the measured value less than 1 V? | Go to step 19. | Repair battery short of harness. |
| 18 CHECK VCU HARNESS CONNECTOR. Check if there is any poor contact in VCU harness connector. | Is there any poor contact in connector? | Go to step 20. | Repair poor contact in connector. |
| 19 CHECK VIU HARNESS CONNECTOR. Check if there is any poor contact in VIU harness connector. | Is there any poor contact in connector? | Go to step 21. | Repair poor contact in connector. |
| 20 CHECK VCU. IMPORTANT: Perform OnStar (R) setup procedure. Replace VCU. < Ref. to REMOVAL , VEHICLE COMMUNICATION UNIT VCU. > | Go to step 22. | ||
| 21 CHECK VIU. IMPORTANT: Perform OnStar (R) setup procedure. Replace VIU. < Ref. to REMOVAL , VEHICLE INTERFACE UNIT VIU. > | Go to step 22. | ||
| 22 CHECK SYSTEM. Run the system and confirm the result of repair. | Was the trouble repaired? | System is OK. | Go to step 1. |
| IMPORTANT |
|---|
| Perform OnStar (R) setup procedure. |
| IMPORTANT |
|---|
| Perform OnStar (R) setup procedure. |
DIAGNOSTICS CHART WITH TROUBLE CODE
ONSTAR (R) CALL CENTER CANNOT SETUP ONSTAR (R) SYSTEM.
DEFINITION: OnStar(R) Operator notifies to receiver that the required setup of the OnStar(R) system is impossible.
Scheme 32
| Step | Check | Yes | No |
|---|---|---|---|
| 1 CHECK IGNITION ON SIGNAL CIRCUIT. Turn ignition switch to OFF. Disconnect connection from VCU. Turn ignition switch to ON (do not let the engine run). Measure voltage between ignition ON signal circuit and ground. Connector & Terminal (i72) No. 31 (+) - Chassis ground (-) | Is the measured value 9 to 16 V? | Go to step 4. | Go to step 2. |
| 2 CHECK IGNITION ON SIGNAL HARNESS. Turn ignition switch to OFF. Disconnect VIU connector. Disconnect VCU connector. Measure resistance between VIU connector and VCU connector. Connector & Terminal (i72) No. 31 - (i71) No. 12 | Is the measured value less than 0.5 ohm? | Go to step 3. | Repair open harness. |
| 3 CHECK IGNITION ON SIGNAL HARNESS. Measure resistance between VIU connector and chassis ground. Connector & Terminal (i72) No. 31 - Chassis ground | Is the measured value More than 1 Mohm? | Go to step 5. | Repair ground short of harness. |
| 4 CHECK VCU HARNESS CONNECTOR. Check if there is any poor contact in VCU harness connector. | Is there any poor contact in connector? | Go to step 6. | Repair poor contact in connector. |
| 5 CHECK VIU HARNESS CONNECTOR. Check if there is any poor contact in VIU harness connector. | Is there any poor contact in connector? | Go to step 7. | Repair poor contact in connector. |
| 6 CHECK VCU. IMPORTANT: Perform OnStar (R) setup procedure. Replace VCU. < Ref. to REMOVAL , VEHICLE COMMUNICATION UNIT VCU. > | Go to step 8. | ||
| 7 CHECK VIU. IMPORTANT: Perform OnStar (R) setup procedure. Replace VIU. < Ref. to REMOVAL , VEHICLE INTERFACE UNIT VIU. > | Go to step 8. | ||
| 8 CHECK SYSTEM. Run the system and confirm the result of repair. | Was the trouble repaired? | System is OK. | Go to step 1. |
| IMPORTANT |
|---|
| Perform OnStar (R) setup procedure. |
| IMPORTANT |
|---|
| Perform OnStar (R) setup procedure. |
DIAGNOSTICS CHART WITH TROUBLE CODE
ONSTAR (R) AUDIO DOES NOT OPERATE.
DEFINITION: Audio system display does not change into "Call", even if all buttons are pressed.
Scheme 33
| Step | Check | Yes | No |
|---|---|---|---|
| 1 CHECK LED. IMPORTANT: Before pressing button, call OnStar (R) call center to notify the inspection. Turn ignition to ON (do not let the engine run). | Does LED illuminate, when all of buttons are pressed one to another? | Go to step 2. | Perform inspection of One or more OnStar (R) button does not operate. < Ref. to ONE OR MORE OnStar (R) BUTTONS DO NOT OPERATE. . > |
| 2 CHECK AUDIO SYSTEM Turn ignition to ON (do not let the engine run). Turn radio ON. Set the volume to comfortable level. Activate all buttons | Does the audio system display "Call"? | Go to step 11. | Go to step 3. |
| 3 CHECK HARNESS. Turn ignition switch to OFF. Disconnect VIU connector. Disconnect audio connector. Measure resistance between VIU connector and audio connector. Connector & Terminal (i72) No. 6 - (i69) No. 5: (i72) No. 8 - (i69) No. 1: (i73) No. 7 - (i69) No. 2 | Is the measured value less than 0.5 ohm? | Go to step 4. | Repair open harness. |
| 4 CHECK HARNESS. Measure resistance between VIU connector and chassis ground. Connector & Terminal (i72) No. 6 - Chassis ground: (i72) No. 8 - Chassis ground: (i73) No. 7 - Chassis ground | Is the measured value More than 1 Mohm? | Go to step 5. | Repair ground short of harness. |
| 5 CHECK HARNESS. Turn the ignition switch to ON. Measure voltage between VIU connector and chassis ground. Connector & Terminal (i72) No. 6 (+) - Chassis ground (-): (i72) No. 8 (+) - Chassis ground (-): (i73) No. 7 (+) - Chassis ground (-) | Is the measured value less than 1 V? | Go to step 6. | Repair battery short of harness. |
| 6 CHECK VIU HARNESS CONNECTOR. Check if there is any poor contact in VIU harness connector. | Is there any poor contact in connector? | Go to step 7. | Repair connector. |
| 7 CHECK VIU. IMPORTANT: Perform OnStar (R) setup procedure. Replace vehicle interface unit (VIU). < Ref. to REMOVAL , VEHICLE INTERFACE UNIT VIU. > | Go to step 8. | ||
| 8 CHECK SYSTEM. Run the system and confirm the result of repair. | Was the trouble repaired? | System is OK. | Go to step 8. |
| 9 CHECK AUDIO HARNESS CONNECTOR. Check if there is any poor contact in audio harness connector. | Is there any poor contact in connector? | Go to step 9. | Repair connector. |
| 10 CHECK AUDIO. Replace audio. < Ref. to INSPECTION , RADIO SYSTEM. > | Go to step 11. | ||
| 11 CHECK SYSTEM. Run the system and confirm the result of repair. | Was the trouble repaired? | System is OK. | Go to step 1. |
| IMPORTANT |
|---|
| Before pressing button, call OnStar (R) call center to notify the inspection. |
| IMPORTANT |
|---|
| Perform OnStar (R) setup procedure. |
DIAGNOSTICS CHART WITH TROUBLE CODE
ONSTAR (R) LED DOES NOT OPERATE.
DEFINITION: When ignition switch is turned to ON, OnStar(R) green LED does not illuminate.
Scheme 34
| Step | Check | Yes | No |
|---|---|---|---|
| 1 CHECK LED SIGNAL. Turn ignition switch to OFF. Disconnect connection from button assembly connector. Turn ignition switch to ON (do not let the engine run). Measure voltage of key pad green LED signal circuit. Connector & Terminal (i73) No. 5 (+) - Chassis ground: (i73) No. 25 (+) - Chassis ground (-) | Is the measured value within 7 to 9 V? | Go to step 10. | Go to step 2. |
| 2 CHECK HARNESS. Turn ignition switch to OFF. Disconnect VIU connector. Disconnect button assembly connector. Measure resistance between VIU connector and button assembly connector. Connector & Terminal (i73) No. 5 - (i70) No. 1: (i73) No. 20 - (i70) No. 2: (i73) No. 25 - (i70) No. 3 | Is the measured value less than 0.5 ohm? | Go to step 2. | Repair open harness. |
| 3 CHECK HARNESS. Measure resistance between VIU connector and chassis ground. Connector & Terminal (i73) No. 5 - Chassis ground: (i73) No. 20 - Chassis ground: (i73) No. 25 - Chassis ground | Is the measured value More than 1 Mohm? | Go to step 4. | Repair ground short of harness. |
| 4 CHECK LED SIGNAL HARNESS. Turn the ignition switch to ON. Measure voltage between VIU connector and chassis ground. Connector & Terminal (i73) No. 5 (+) - Chassis ground (-): (i73) No. 25 (+) - Chassis ground (-) | Is the measured value less than 1 V | Go to step 5. | Repair battery short of harness. Replace button assembly. < Ref. to REMOVAL , BUTTON ASSEMBLY. > |
| 5 CHECK VIU POWER SUPPLY. Turn the ignition switch to ON. Measure voltage between VIU connector and chassis ground. Connector & Terminal (i73) No. 16 (+) - Chassis ground (-): (i73) No. 32 (+) - Chassis ground (-): (i73) No. 22 (+) - Chassis ground (-) (i73) No. 27 (+) - Chassis ground (-) | Is the measured value more than 9 V? | Go to step 6. | Check fuse or repair open circuit in harness. |
| 6 CHECK VIU GROUND. Turn ignition switch to OFF. Measure resistance between VIU connector and chassis ground. Connector & Terminal (i73) No. 1 - Chassis ground: (i73) No. 7 - Chassis ground | Is the measured value less than 0.5 ohm? | Go to step 7. | Repair open circuit in harness. |
| 7 CHECK BUTTON ASSEMBLY HARNESS CONNECTOR. Check if there is any poor contact in button assembly connector. | Is there any poor contact in connector? | Go to step 8. | Repair poor contact in connector. |
| 8 CHECK BUTTON ASSEMBLY. Replace button assembly. < Ref. to REMOVAL , BUTTON ASSEMBLY. > | Is repair work completed? | Go to step 9. | |
| 9 CHECK SYSTEM. Run the system and confirm the result of repair. | Was the trouble repaired? | System is OK. | Go to step 8. |
| 10 CHECK VIU HARNESS CONNECTOR. Check if there is any poor contact in VIU harness connector. | Is there any poor contact in connector? | Go to step 11. | Repair poor contact in connector. |
| 11 CHECK VCU. IMPORTANT: Perform setup procedure of OnStar (R). Replace vehicle interface unit (VIU). < Ref. to REMOVAL , VEHICLE INTERFACE UNIT VIU. > | Go to step 12. | ||
| 12 CHECK SYSTEM. Run the system and confirm the result of repair. | Was the trouble repaired? | System is OK. | Go to step 1. |
| IMPORTANT |
|---|
| Perform setup procedure of OnStar (R). |
DIAGNOSTICS CHART WITH TROUBLE CODE