Does this car use a cartop encoder? If so make sure BJ1 on the relay pilot board is in the 1-2 position, and the nc contact on rr relay is good. This error can sometimes be caused by a loose ground wire in the cartop position encoder or the +12vdc to the position encoder being flaky. Are you getting the+12vdc from the controller? If so check that it is stable. I think I had this problem once and it was the +12vdc dropping from the controller to the cartop. If I remember correctly I used the 12vdc from the Zap unit to power the position encoder. Not sure about this, it has been a while. Something for you to look at. For sure check grounding and shielding ground from the position encoder.