P0300 and p0753 99 Jimmy 4 x 4
 

My Jimmy is returning these codes. Here are my questions: are they or could they be interrelated? I ve read that these issues could be caused by a bad ignition switch or it's related wiring. If that is the case would the tranny not shift correctly? It runs good but when I get on the highway the SES light will start flashing and the tranny won t shift into fourth. When doing 70 I am at 3000 rpms. Also it makes a ticking or clicking noise. Any thoughts?

Have a read through the diagnostic pages below:
P030x - Random/Multiple Cylinder Misfire Detected
P0753 - Shift Solenoid A Electrical

These two codes likely are not connected to one problem. Let us know what questions you have after reading through the diagnostics & associated pages and try some things out.