Electrical issue

I have a 2009 Infiniti G37 and I’m dealing with the weirdest electrical problem I’ve ever seen, and it ONLY happens when it rains.

Symptoms: • ABS + VDC/traction lights on • Speedometer sometimes dies, then randomly comes back •Trans shifts hard through 1 & 2 then lives in 3 • HVAC/AC controls completely dead • Start/Stop button won’t shut the engine off (button does nothing) • But the car runs and drives perfectly fine (besides shifting issue) • Gauges came back after cleaning ipdm connector, but the other problems stayed • Only happens after/during rain or moisture

What I’ve tried: • Cleaned and reseated the IPDM connector (this fixed it once before but not this time) • Disconnected the battery • Checked fuses under the hood and inside • Verified brake lights work (so it’s not the brake switch) • Left the IPDM unplugged and the problem STILL happened

The weird part: Last time I cleaned the IPDM connector, EVERYTHING came back and the problem went away for weeks. This time, cleaning it only brought the gauges back but the car still won’t shut off and HVAC + ABS/VDC issues stayed.

Additional info: • Car has no issues starting • Engine runs totally normal • This ONLY happens after rain • Once it dries out, the problem sometimes “fixes itself” randomly

I’m losing my mind here — has anyone had this combo of symptoms before? Is this an ABS module issue, BCM ground problem, wheel speed sensor shorting when wet, or something else?

Any advice or someone who’s seen this before would help a lot. I’m tired of guessing

I used ChatGPT to sum it all up but yeah I’m just kinda loss on what to do here the first time it happened I kinda just pulled a bunch of stuff apart and ended up cleaning the idpm connector and the wires at the top and then the fuse box and while it didn’t really fix it ig it did help because it ended up fixing itself, another thing is currently if I conncect the battery it will start but won’t turn off and the VDC and SLIP light is on and it runs and drives semi normal like no hard trans shifts but the turn signals / headlights don’t function it’s only on And they don’t turn off and the a/c / heat controls don’t work everything else functions normally it’s not the bcm because it’s dry and I did the sunroof drains already so I’m really just lost I know that that area is susceptible to water because I think my fender has a gap that’s letting excess water in