+12V on Nitrous IN (diagnosis help!)

[alienblood]

Hey all...
In the midst of a bunch of other repairs/upgrades to the harness, I finally connected AC and fan controls to my MS3X (MS3 v.3.0 + expansion card) In my 1987 BMW 325e.
using Nitrous IN as +12V trigger (because the e30 triggers everything with +12V)
MS3X Injector outputs for Compressor and Hi/Low fan relays (no problem there)

This worked perfectly for two days until I updated firmware to 1.4.x to solve some CL Idle issues, and that evening, I noticed that the AC and Fan indicators were illuminated in TunerStudio, even with the switch off. I disconnected Nitrous IN from the rest of the harness, and measured +11.4V on the Nitrous IN pin at the DB37..... so Megasquirt sees an AC Request, even when it's not there. I'm not sure if this is a software/firmware issue, or if there is a component failure/short internal to the expansion board. Any diagnostic help would be greatly appreciated. I don't know where to go from here.

In the meantime, can I use one of the Ground inputs (datalog, launch control, tableswitch), set to "Inverted", or can those not handle a +12V signal??

MSQ to be uploaded as soon as I get back to my laptop.

[grom_e30]

have you got the nitrous pull up jumper fitted? if so try removing it

[alienblood]

Brilliant!! I don't understand why it functioned "properly" for two days, though.... Either way, I just removed the jumper. If you don't hear from me, that means it worked, and thank you SO MUCH!!

[alienblood]

Installed
Tested
Perfect!

Thank you again!

[grom_e30]

i seem to remember there was a bug some time back where the polarity on that input was incorrect in some f/w's i may be wrong though.