I have a 78 f-150. The right half lights up but the left side doesn't. Any suggestions?

 

My suggestion is called "troubleshooting".

 

It could be as simple as the little cluster lamp (most inboard) being burned out. If you have the composite material cluster-back, it could be crumbling away, and the bulb socket is no longer making good contact with the trace. I had the exact same issue with my 77, and it was the disintegrating cluster. I got one off eBay.

A good upgrade, assuming you have the good plastic cluster back, is a pair of cluster lamp LEDs. I got a set from O'Reilly today, and they made a big difference.

You only need two, one for each side of the speedometer

Here's a link: https://www.ford-trucks.com/forums/1...per-truck.html

 

I figured it was something like that. Just didn't know and was going to get some ideas before tearing into the dash. I didn't know if the circuit board may have been messed up because you can see that my right turn signal is somewhat illuminated as well

 

my turn signals light up like that when I had ground issues on a light socket on the side that was on, either front or rear