HT740 air modulator questions

[Iceni John]

My cable-shifted HT740 has an air modulator:  air first goes through a Bendix pressure regulator, then to a Schrader 74312 solenoid valve and finally to the air modulator on the side of the transmission near the shift linkage.   How does this work when I have DDEC II, using a Williams electronic accelerator pedal for the ECM?   What confuses me is that I also have a cube relay wired to the Schrader solenoid valve: is this relay connected to the ECM?   My bus's electrical and air schematics don't show the transmission modulator system at all, and I can't trace back the wiring to the relay.   Is the air supply to the pressure regulator directly from the main air compressor or from elsewhere?   It doesn't appear to be connected to the D2 air governor, but maybe it is somewhere that I can't see it?

Sorry for all these arcane questions!   I have a very slow upshift from 3 to 4 when the fluid is cold, and I'm wondering if I can adjust anything to quicken that shift.   Otherwise the transmission shifts well, and it was dyno'd at a transmission shop when we rebuilt the engine:  they said it was working just fine.

Thanks, John

[luvrbus]

I don't have any information on how Crown has theirs set up,it is a common setup on Prevost,MCI and Eagle with the DDEC and 740,and I don't know of any adjustment other than shift points controlled by the trimmer valve setting The 740 has always been slow coming from 3rd lockup to 4th converter unless shifted manually. The air modulator is supposed to be replaced every 100,000 or less miles per the book but I have seen those 25 years old still working without a hitch ,I wouldn't worry to much about the problem myself   

[Iceni John]

OK, many thanks for that!   As always, you know exactly what to do (or not do).   I'll just leave it alone for now.   The transmission shop had no concerns with it when they dyno'd it last year.

John