Hello I have a 2006 hummer h3. I have known for a while that I have O2 sensor faults so a check engine light doesn't bother me anymore. Anyways my speedometer has started jumping all around while driving and at slow speeds started shifting weird. I instantly changed out the vehicle speed sensor just because it was a cheap and easy thing to try. I checked all the connections and everything looked fine. Same thing. Then it got worse. Intermittently the speedometer won't read anything and I won't shift out of first gear. I checked my codes and I had P0315 for the crankshaft position sensor and multiple cylinder misfires. Any idea how all this could be connected??? Or any tips on what to check first?

 

You Ignore the CEL? How do you know when there is a real problem?
Scan and post ALL codes. Also post any electrical mods you performed.

 

Why assume anything is "connected." You have multiple problems going on at the same time. Fix what you know is broke then diagnose fully what is left.

Would you happen to have a sunroof?