Hello, I had the same problem with my BMW X5 2002, the day I buy it, that same day gave me problems of reverse, the reverse lights turned on but remained neutral, the next day the reverse worked, change the solenoids and The problem followed, finally end up changing the valve body for a used one that buy for 150 $ and go 2 years without problems. Check Sonnax, the made hi quality valve bodies, around 500$