I have an 89 CRX w/b16 and ever since I had the swap I have been throwing an ECT code. The stumper is, I only throw the code once I shift into reverse. Today I pulled the reverse sensor and the code is gone. Fixed the ECT problem but now I do not have backup light! I am stumped, my mechanic is stumped and I still do not have backup lights. Once I plug the sensor back in I trip the CEL. Anyone have any suggestions?? Maybe a fix would be to try to park so I never have to put the darn thing in reverse.

 

from your description of the problem, your CRX is HF which had input from back-up lights to ECU to increase idle when in reverse - cut the green/black wire at ECU pin B9 - problem will go away