ABS lamp on

I live in Sweden and I am not able to get my car registered because of the ABS indicator lamp is lit up, and I can not get it to pass inspection as long as they light up. First of all my car does not have ABS brakes so why they light up is beyond me. Now my mechanic told me I could do two things, either manually disconnect the warning lamp inside the instrument panel or two, get a new "Denso data box" and install that and hope that it will get fixed. So I am not sure what to do here? It is very hard to find a replacement Denso box for my car's make and model, so I wonder if someone familiar with Denso boxes can tell me if another year would work? I have located 1991, 1993 and 1994 Grand Prix cars sitting at the junk yard but before I start removing any of them I want to know if they are compatible with a 1990 model, any suggestions? Thank you