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'03 Model:

Open the trunk lid, and remove the OnStar control unit cover.
Disconnect the 12P connector from the OnStar system interface unit.
Inspect the connector and socket terminals to be sure they are all making good contact.
- If the terminals are bent, loose or corroded, repair them as necessary, and recheck the system.
- If the terminals look OK, make the following input tests at the connector.
  - If any test indicates a problem, find and correct the cause, then recheck the system.
  - If all the input tests prove OK, the control unit must be faulty; replace it.
Fig 1: Identifying OnStar System Interface Unit Connector Terminals
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Fig 2: OnStar System Interface Unit Input Test (Connected)

G01157251

Courtesy of AMERICAN HONDA MOTOR CO., INC.