This morning working on a Hummer H2 cluster, it was dead when I received it, it now works but not 100% sure I fixed it. I will be switching it on and off all day to see if it fires up every time.
Just repaired a 2003 Tahoe cluster with the usual problems except motors were still good. Sometimes it wouldn't come on, sometimes it wouldn't shut off and kill his battery and of course the PRND321 display was dead. All the bottom bulbs were burnt so I LEDed it in cool white.
18:30 Just finished a 2005 Venture 3 gauge cluster.
AU3 ( Electric door lock ) means your truck didn't come with remote keyless entry from factory. Contrary to what's been said previously here you can still get OEM remote start but the kit is very expensive because it includes a hood switch with harness, key FOBs (2), a different RCDLR an AP3 sticker to apply over your AU3 and an activation code, all this has to be done at the dealer or a certified GM shop. They will sync the new RCDLR to your BCM and with the activation will be able to download the proper menus to your BCM to enable these options.
03-04's were notorious for having their clusters fail and not turn ''OFF'' after you removed the key. This will kill your battery over night if both delay circuits stay ''ON''. If only one stays on it could take 3 days to kill the battery because you'd be drawing 250ma for each delay circuit. Now this could be intermittent for a long time before it actually fails completely and never shuts off. Several ways to tackle this.
1. You can pull the cluster fuse and see if it happens again.
2. Swap the cluster with a known good one.
3. Have the cluster tested by a professional.
I repaired an 04 cluster this morning that had this problem. I can help you with this if this happens to be your problem.