I have an 87 Trans Am with a LG4 engine. I'm trying to diagnose why my SES light does not illuminate at all. Upon tracing the SES light wires I come to this blue case/box that looks like something plugs into it but there is nothing in it on my car. Can some please help me identify this and maybe shed some info . Am I missing something?

 

I found the answer myself from another post. This is the SES Light driver module. Without it installed your SES light will not illuminate and I believe you will not get communication with a scanner through the ALDL port.