Think i've got a wiring problem and could use sound advice.
 

problems
1) tach doesn't work, just kinda tweaks every now and then, often past redline. (friend nick named it tweak)
2) my check engine light came on but no codes (second time in less than a month)
3)one time occurence, my seat belt light did not come on when i wasn't buckled up. didn't come on the entire way home from work.


Anyone know what the problem might be? how hard is it to fix?