I realize your question is about self-etching primer, but the Interprotect 2000E instructions have some very specific steps to prepare aluminum. Here's the a snippet that might be of interest:
"ALUMINUM: Degrease by wiping with a rag soaked in Fiberglass Solvent Wash 202. Grit blast, grind with a 36 grit disc, or sand with 40-60 grit sandpaper. If gritblasting, use aluminum compatible materials. Bring the surface to a uniform, clean, bright metal surface. A surface profile of 23 mils (5075 microns) is recommended. Remove sanding residue with a brush, vacuum or by blowing off with a clean air line. Within 1 hour of preparing the surface, apply a coat of Interprotect 2000E thinned 1520% with the correct thinner. Apply 45 additional coats of Interprotect 2000E"