Does the I405 go to San Diego?

No.

It connects to Rt 5. Rt 5 goes into SD.

Rt 405 connects to Rt 5 near Slymar (LA) and Irvine.

Rt 5 runs on the east side of LA.

Rt 405 runs on the west side of LA and is about 70 miles long.

the 405 runs into 5fwy and the 5fwy go to san diego

I-5 is the only north-south direct route to San Diego from Los Angeles. The I-405 basically runs parallel to the I-5 for its life. In the direction you are interested in, the I-405 and I-5 merge just south of Lake Forest, past the old El Toro air base.

No, not all the way. But if you take it south to the end, you can then get on the I-5 and take that the rest of the way to San Diego.

The San Diego Freeway (I405) does NOT go to San Diego. It will connect with I5 however which does. I'm guessing you already knew this b/c if you were able to create an account here you were able to use googlemaps.

The 405 in LA/OC is a bypass road from the I-5 along the coast. It starts on the northern end of the San Fernando Valley and ends just south of Irvine (Lake Forest area).

I-5 is the primary artery between SD to South OC.