I adjusted the timing on my 1990 Loyale yesterday. Both the Subaru SM (1989) and Chilton say that when I connect the "green" diagnostic plug (on the firewall in my 1990 Loyale) the "check engine light" should be lit. But...my CEL is already on (EGR solenoid problem) and when I connect the "green" connector my CEL turns off???? Dazed and confused. Any advice?

I am not sure how that can happen though it isn't a real problem I wouldn't think. From my past dealings with the CEL circuit, the ECU makes a ground connection to turn on the light. It is done through an IC. Perhaps having an existing problem changes the logic to the light control. It would be nice to know what happens when the code is cleared.