Yes, you can scan it for codes but without a light, you would need a scan tool that will read history codes.
Also, if there is no light or codes, it is a mechanical failure which means there would be no codes.
As far as testing, you would need a set of pressure gauges to attach to the transmission and check main line pressures and application pressures.
Roy
Thursday, March 8th, 2018 AT 4:17 PM