Faulty ground causing these issues?

Hey guys, I need some help! My Patriot gas gauge is showing low fuel (even when full) then comes back to show correct level. Speedometer will drop to zero, then shows correct speed. And brake light comes on, then will go off...all while driving. Sometimes this all occurs at the same time. Took it to O'Riley's to be put on diagnostics computer, it shows fuel pump relay. Took it to a mechanic and he says the same thing. But I'm not understanding how fuel relay can effect speedometer and brake. Any assistance is appreciated.

 

Since two sources confirm an issue exists with the fuel pump relay I’d change it whether or not it makes sense affecting or causing other issues. Take care of one thing and move onto the next issue.

 

I apologize aggrex, I must have deleted my main question while editing my main post. Could it all be caused by a faulty ground? And if so where might I find said ground?

 

On some vehicles bad grounds could trigger dash lights etc. Follow your ground wires from the battery. Usually terminates at the frame and engine. On older vehicles cleaning the battery terminal connection may not be enough as corrosion can occur further away as seen in these pics.

 

Thank you! I'll update later.

 

Ok so my update on fuel gauge, speedometer and brake light issue... I have taken my Pat to 2 other mechanics (now totaling 4). Each have made different diagnosis. 1) fuel relay - got second opinion 2) fuel relay - Asked this mechanic if issue could be bad ground - checked relay it's fine & scratches head. 3) only thing showing on $10,000 computer TPM so it needs correcting before we can go further. Ask about checking ground, looked at ground ( visual scan) nope it looks good. 4) O2 sensor - needs replacing but he didn't have enough time/want to take dashboard off to replace it. Again looked at ground said it looked ok to him.

All issues still occuring. New issue today Pat will not move out of park. Found manual parking brake release but still will not move out of park. Suggestions??

 

Remove the dashboard to replace an O2 sensor? Not having enough time...might be doing you a favor

 

This was the same mechanic that I used to replace my A arm. So I've used him in the past. 30+ years experience as mechanic with local road dept. He removed both front tires to clean wires to see if that may be causing my issues, but forgot to tighten my lugs on passenger side. I felt a wobble going down the road, pulled over to check tires and saw I was missing a lug. Decided to make sure remaining lugs were tight and got 4 way out. Passerby stopped to help with his impact. So no I will not be using him again.

I'm at my wits end and can't afford a tow to another mechanic and the work/parts. Just trying to get the blasted thing in gear so I can get it to someone that can help figure out the other issues. Any suggestions aggrex?

 

https://www.youtube.com/watch?v=3LlqEGzl0yQ

 

https://www.700r4transmissionhq.com/jeep-patriot-stuck-in-park/