Battery Parasite Solution
 

I hope I am not ahead of myself here, but I have a Black 99 Sedan Deville.
Battery would drain and ground to chassis would show 1.5 or more volts.
Been working on this for six months. Relays, fuses.
Might have a solution!!
Back seat out and finally took out the PZM box. No relays inside, just normal looking ic's. In and out, no difference. This afternoon before putting it back hit all pins and contacts with contact cleaner.
Oh how I hope. Things are working exactly as they should, going to sleep with .04 draw and even dropping!!!
Believe me, I have been all over this car with the Factory manual! Pulling fuses, relays, all hints led to PZM.

After cleaning pins and contacts on PZM with cleaner, goes to sleep just as it should!!!

welcome. Cool you fixed your problem and thanks for sharing.