Dave;

As usual, thanks for your extensive help. You said:

If you're losing your radio code (and have not disconnected the battery or run it stone dead) then I would be more suspicious of a poor connection, probably a ground connection and my armchair logic has me guessing it's one of the battery post clamps or between battery negative and main chassis ground point.

I had partially overlooked this. IE I had cleaned the main + post but not the accessories wire connected to pos cable. There was some corrosion between the 2--potentially enough to resist 12v clock memory. We'll see what happens..

I ran a few voltage drop test--neg to block, alternator to pos cable and I think alt housing to pos cable and it all came in under .2v difference.

The battery has sat for over 12hrs with cable removed and has gone from 12.8 (probably surface voltage) down to a solid 12.6.

Here are some test I've run:

- Resting voltage 12.73; 14 hrs later 12.59 (drop of .14v)
- running w/ headlights/full-speed heater/defroster render 13.42v
- running no accessories = 14.05v

As well, I took currents reading from both pos/neg cables to battery post and the draw was 12.5ma. I don't know what's normal but this seems very low, with respect to how much power the battery is fully capable of.

I took the brushes out and slip ring groove is <1mm; brushes 5-6mm left.

I haven't done the other tests you suggested. I only saw the main battery cable post [on back of alternator and a] ground to intake manifold. Nothing about D+ or D-.
--
Norm Cook Vancouver BC; 1989 745T 202,000KM