As the title says, my speedometer is acting crazy. It goes off and on when im driving, same with the temp gauge, it goes up and down. Also, my tachometer is acting crazy too. It’ll turn off on it’s own when im driving. My obd too wont communicate with the ecu(idk if it is because it’s a cheap one)

i already checked alternator and the 42 pin for corrosion so any help is appreciated as this is my first car

videos are in this link

https://imgur.com/a/ZZBWjl5

 

This type of behavior can sometimes be attributed to signal interference on the CAN bus. This might also be causing the issues with you scanner.
The best way to check this is with an oscilloscope.

 

Does it behave the same when you are just idling and not moving. If it stops then it would suggest a loose cable or connector.