1986 F-150 Electrical Issues

I missed/forgot it.    So, glad you caught it.

Thanks guys.  Napa has the factory style cable with the "flag" for $20 so I went ahead and ordered it.  I have the catalog downloaded, just need to verify some of the connectors to make sure I get the right ones.  probably going to start replacing some sections of the harness as time allows to get rid of some of the POs crappy splices for accessories.  Also have a few connectors that have had oil leaked on them and corroded wiring because of it.

Just a quick update. After flooding the inside of the drivers side going through the car wash, my rear lights are magically 100% working.... Wondering if the ground behind the driver's side kick panel is an issue.  Hoping to have sometime to work on the truck next weekend.

May not be relevant as this tidbit came on an 89 model, but I too had dim taillights along with some fuel pump problems.. I discovered that my taillight harness ground actually measured about 3V to frame ground. Not good. On this year F150, all the rear wiring picked up it's ground from the main harness in the engine bay. All grounds in the engine bay were good. No voltage drop, everything 0V to frame. Found the ground ran through the connectors at the R inner fender, particularly a circular 3 pin connector via a black/white wire identified  as circuit #57. Cleaned up this connector and problem solved.

I still have a fuel pump issue with switching tanks.  I can only run the front tank. Switch appears to be good, but nothing happens when I switch to the rear tank.

I did pull that connector apart and cleaned it up, evening worked until I drove the truck again.  Now I can't get that connector apart again.  It does have a rather rough looking/partially corroded gelling from years of brake fluid dripping in it, but I haven't had time to order new connectors or at least replace that ground.

Now that you've said that, I need to try switching tanks and see what happens.