Recently, I was merge off the interstate when I felt a firm jerk while braking. I tap the gas and my rpms shoot up because my transmission down shift to 2nd and would no longer shift up or down from that point even if i switched over to manual mode. I pull over and restart the car and it works fine. Now my car does it randomly and id have to restart my car twice for it to go back to normal.

I've already checked the continuity between the tcm and transmission harness and it all turned out good. I've also checked the resistance of the Low Coast Brake solenoid which also tested good based off of the information I read in the manual. I even replaced the solenoid with a used one I bought off of a car in the junkyard. Problem still exists.

P1730 A/T Interlock
- Low coast brake solenoid valve harness is open or shorted
- Low coast brake solenoid valve circuit poor electrical connection
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Faulty low coast brake solenoid valve
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Faulty Automatic Transmission Fluid (ATF) pressure switch 2

P0550 Power steering Pressure Switch

2003 G35 Coupe 5at 177,701 mi
Stock 17s
Mods: Stillen Z Tube, Megan Resonated Test Pipes (roughly a week before the problem)

The only thing I haven't done is checked the actual brake solenoid valve in the valve body. I simply changed the Solenoid. HELP PLZ!!