I have a 1990 240sx SOHC. Speedometer comes on and off at random. I've tried 2 different gauge clusters and 2 different gauge clusters harnesses. And yes they are hooked up the right way. Also the gauge cluster lights EXTREEMLY dim when the running lights are on but they turn off completely when the head lights are on. I Read a while back on a forum (maybe this one) that some one was having a similar problem and they said the culprit was a white box under the driver-side dash and I was wondering which one it was cause there is a small one and a big one.