Component Tests and General Diagnostics

Fault symptoms
The OnStar system does not start or there is no diagnostic communication with the system.

Conditions
No trouble codes stored in the car for the current fault symptom.

Diagnostic help
In one of the units (OIM and VCIM), one of the communication, power supply or ground leads can be faulty.

Fault Diagnosis Procedure (2007;2008;2009;2010)