I made up the cable and downloaded the software for my 94 RR Classic a couple of years ago, it has always been somewhat temperamental in that it will take up to a couple of minutes to establish 'idle' and communicate with the ECU. I currently have a hard fault (suspect the compressor seal is worn out after tolerating a leaking spring for too long- have replaced the spring and ordered the seal from HardRange), the other day I tried for hours to get the laptop with the EASUnlock to communicate with the ECU, with no success. I'm wondering whether perhaps the NPN transistor in the cable has died and I'm thinking I might try replacing the transistor.
I know pretty much nothing at all about transistors. I had a spare transistor of the same type when I made the cable, but I gave it, along with a spare connector, to another member who was making a cable in W.A.
I have a pack of NPN transistors but they have a different code number. Can I use one of these, or do I need to find one with the specific code? Or is there some way I can check the integrity of the existing transistor? I have a multimeter but, like I said, I know stuff-all about transistors so don't know how to check one.