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Q: new stereo unit not working, interior lights and fuel level not working or showing up

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So I installed a new Sony stereo unit, we Had to remove the older after market head unit, after it was removed we had to re wire the cables to the new head unit and I'm confident that we re wired the colour coded wires correctly. I disconnected the battery first before I went to remove the head unit, but after installing the new unit it doesnt turn on we also found out that non of her interior lights are working now and the fuel level isnt showing up anymore? i reading some similar problems and some say that it could be the battery ground not hooked up properly or that head unit cables could be doing this, please I need your help Thanks Kennedy

My car has 188889 miles.
My car has an automatic transmission.

Following the colors of the wires is not a full proof method to be sure you have made the correct connections. You clearly have some connections that are not correct. The only way to figure out what is what in the wiring harness is to find yourself a wiring diagram for the car and hopefully you have a detailed wiring diagram for the stereo. With the two of these, disregard the wire colors and confirm the power connections go to power connections, grounds go to grounds etc. This can be time consuming so give yourself time to study the diagrams.

When wrong connections are made, the symptoms that follow are always going to be random and unpredictable, so don’t worry yourself to much with what is happening with the car. First you need to start with the correct connections. I recommend starting with a few wires at at time. First power and ground then maybe speaker wires and antenna. If you make these connections and the stereo begins to work, you will know your on the right track. Make one connection at a time and observe if there are any problems that occur. If a problem occurs, you can isolate it to the last connection you made.

The use of a test light to confirm power with the key on or off is valuable with such an installation. Be patient and I’m sure you can figure this out.

If you find that this is more than you bargained for, consider YourMechanic, as a certified technician can help you sort out the issue with your electrical components.

Good luck!

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