My gauge lights turn on / off on a 1 second on-off basis when driving. This is post-pnp install and turbo install.

Not sure where to begin?

 

Your wording is kind of weird. This only happens when moving? is it flickering or actually a timed on/off as if it's connected to a relay?

I would start with loose connections, obviously. Rule out the easy ****. From there I'd meter the harness at the cluster to see if the voltage is actually flickering or if it's isolated inside the cluster.

Honestly you probably just have a loose bulb.

 

Sorry about the wording. I don't believe this is a vibration issue or a connectivity issue. All of the gauge lights in the instrument panel turn on and off on a 1 second on, 1 second off basis. I will need to check if this is also the case when the car is off, but the ignition is on.

 

No problem - it just kinda made it sound like it only happens when moving, which would be interesting.

I would still start with the easy things, inspect the fuse for the cluster and re-seat it in the fusebox if it looks OK. Re-seat the connections behind the cluster.

If you're still seeing a timed on/off, you have something pretty odd going on. You'll definitely need a multimeter and wiring diagram to troubleshoot further. In this case I think it would be easiest to start testing at the cluster and work backwards on the circuit from there. All of the gauge illumination runs through the stalk switch, but I can't really see that causing this issue.