[djcwardog]

I’ve accessed the service info and diagrams as suggested. Not a bad resource for $15 for 24 hours of access! Not everything came up for my 2021 Camaro, but I did see everything needed for a 2020 Camaro. While I was in there I took a look at the 2015 and 2017 Camaro for their cluster and HUD interface. Definitely changed after 2015. From a 2017 to a 2020, it looks like S27 and P29 may still be the same, but the P16 cluster wiring is a bit different. Here are the three wires:

Power definitely is taken from the 15 amp fuse which runs a RD/BU 0.5 (thicker) wire to pin 7 for “Secondary Fused Battery Positive Voltage 32”.

Looks like the ground is still a BK wire at pin 19.

Pin 21 is still used as a two-way data relay GN/BK wire between the HUD and the cluster, but it’s now called “Instrument Cluster LIN Bus 1”.

Now I have to hope that they didn’t change things up from 2020 to 2021. Anybody know if a 2021 HUD does things that a 2019 or 2020 doesn’t? Perhaps it was just when they went from B/W to color a few years before? By the way, I checked out a 2019 Yukon 4WD (my wife’s ride) and its HUD/cluster wiring seems similar to the 2020 Camaro and why not? Apply the tech across the platforms!