what does the signal generator do
I have found that the Toyota electronic ignitions severly **** the timing while cranking when they start failing.
When I come across a Toyota that starts very hard, but runs fine, I try advancing the timing while cranking. If it starts fine while the dist is advanced, but then runs lousy because the timing is so far advanced, it's time for a new dist.
Although it's cheaper to just replace the ignitor, I found out the hard way to replace the entire dist- dealer won't warranty individual dist parts, just complete dist.
What is the problem you are having? I know they are known for breaking the signal wire at the connector. If you put your email in your profile than people will get the info to you.