The passenger blinker in the front of the truck is really dim when the right turn signal is engaged and turns off when the headlights are turned on. With the headlights on, the indicator lamp on the dash lights up solid.

Not sure where to start on this.
Any help would be great. Maybe a bad ground?

 

Forgot to mention that this is an 87 f150, 4.9 i6 manual transmission extended cab.

 

I'm also having an issue with the truck stumbling and bucking. I pulled the codes and get 33- egr valve not opening detected, 67-Park/Neutral Position (PNP) switch circuit open - A/C on during Self-Test, and 84 EGR Vacuum Regulator (EVR) circuit failure. I can't help but think this is also related somehow to a bad ground.

 

Sounds like you got a bad ground causing power to flow backwards through something. How are the main body to battery grounds?

 

First of all thank you for your reply Lead Head. I have checked on the grounds that I have seen from the top. Off the battery there are three grounds. One main that goes to the motor, and two small ones with plugs to disconnect them in line. I also checked the two right above each side marker light and the one in the middle of the firewall that goes to the transmission area. I'm not sure what you mean by main body to battery grounds. Thanks again