The 2006 Chevy Cobalt doesn't have a dedicated "secondary injector relay." The fuel injectors are controlled by the Powertrain Control Module (PCM), and there isn't a separate relay specifically for a subset of injectors. There's a main fuel pump relay, and the PCM uses this relay (along with its internal circuitry) to control all the fuel injectors.
If you're having fuel injection issues, it's unlikely a relay is the problem. The issue would more likely be within the PCM, wiring harness, injectors themselves, or the fuel pump. You'll need to use a scan tool to diagnose the problem properly.
