False Oil warning - Typ 89

[tihol tiholov]

I asked this and no reply, so I'll try again differently.  Can't find it in the knowledge base or the archives (hard searching there).  
1. Is the blue/black wire supposed to be attached to the single-wire oil pressure sender for the check system (lower of the 2 senders on the block)?
2. What does the red oil symbol, displayed by the check system, mean exactly?  Is it a warning for oil pressure out of spec or is it also related to the temp sender?  On my car the oil symbol flashes 3 times with the tripple chime on after I go through the check system symbols with the ignition on, even before starting the engine.  When running it warns me at about 3K RPM.  This after renewing both press senders.  The new single-wire sender was spec-d at 0.15-0.35 instead of the superceded old one 0.15-0.45, if that matters.  Oil seems enough, well and kept in engine.  Would a new oil temp sender fix this or, god forbid, a new oil pump?
Any help will be greatly appreciated,
Tihol

TT