The dome light diagram is quite simple. all 4 of your door switches are grounded to the body where they mount. the wire leads run threw the insterment panel junction block, then out to the dome light. the dome light has a 3 contact switch, one contact being "OFF", second contact being "DOOR" and third contact being "ON".
Dome light removal video: http://www.youtube.com/watch?v=wv2CU9VAHFg
Get the codes using a scanner
blinking red light
yes
How can I replace the headlamp on a 2000 Saturn SL1
yes
they are the same fuse. but at leas ton my sl1 its the same fuse as the power locks too, so those buttons wouldn't work.
no
timing for spark plug wires for saturn sl1 1996
exact fit fir the sohc engine is 93 or 94 only
5w30
The speed sensor on a 1999 Saturn SL1 is under the transmission. It is below the fittings for the transmission cooler lines.