Well I've been having a new weird electric issue with my 77 150. To start when I turn the headlight switch on blower motor boggs down and to add to that only the headlights come on (and flicker)(I also have no interior lights) while the side marker lights and park lights in the front stay on for a few seconds then turn off flickering on every once in a while) and nothing besides brake lights work in the rear I can hear the relay in the switch clicking when it does. and I don't know if it's connected but sometimes the blower motor stays on after the key is off and out of the ignition(not on high but on a very low speed only happens every once in a while) I've replaced the headlight switch, ignition switch, all the fuses and the hi lo beam is moved to a on off on switch on the dash. I've also been through almost all the wiring and cleaned up any grounds or connections/wires that didn't look good. The owner before me did install aftermarket gauges for every gauge also he was a home electrician so it's not pretty but everything isn't to hacked together. He also electrical taped all of the wiring front to back so I have to assume those wires are good. I daily drive my truck any help I can get would mean the world to me.
Derek

 

Derek, Welcome to FTE
It looks like you did what I was thinking of but lets go back over it just in case.
Start at the battery, ground goes to the motor and then to the frame. Most miss the frame.
My 300 goes to the frame then to the top starter bolt as 1 long cable but others have used 2 cables.

You want to run a 10 ga. wire from the motor. Back of head bolt or a intake bolt to the firewall. This grounds the cab as it sits on rubber mounts.
This could be all your issues but check all of the above.
You may also want to run a 10 ga wire from the bed to the frame to make sure it is grounded too.

I would also clean the positive side of the wires at the solenoid to make sure they have a good connection.
I would pull all fuses and make sure they are good. If they are the glass type clean the ends and holders before you put them back in.
If blade type fuse maybe put them in & out a few times to clean them for a good connection.

Light bulbs are any of them LED's? If so replace hem with good old bulbs for testing and once all works then change to LED's as some of them can be bad or need to be installed differently.
I would install all new bulbs and then there check the sockets if they are clean and good shape.
Now know todays "new parts" may be bad out of the box. So you thinking any of the switches are good, maybe and need to be checked.

The clicking of the head light switch of the breaker tripping can be 2 things, bad new part or a short in the system.
The breaker should only be for the head lights so if off should not trip it is dose you get bigger problems.
Starting with parking lights, **** pulled out 1 notch do we get the breaker tripping, what lights are working out side and in (dash).
If breaker is tripping you will need to find out why and fix it before going farther.

If just lights are not lighting out using a old bulb test light not a LED one see if you have power at the socket(s) and if not start tracing back to fins out why not.
Note the fuse for running / marker lights may not have power to it till the lights are turned on.

Will let you work on the running lights first and move on to the head lights if not working.
BTW pick up a head light relay kit. LMC, DC, JBGY and Ebay have kits. It is a plug and play, no wire cutting & splicing.
Dave ----

 

Thanks for the help I'll check the ground for the bed and to the frame in the engine bay for the positive/negative. Connections.
I know the ones from the chassis to the motor are good but most likely dirty. I put a new cable on that goes to the negative on the battery terminal.
The only LEDs I have are the side marker lights and I put those on a year ago so I doubt they'd be bad I'll still check anyway with the old stuff that I know is good. I also went over the wiring to the marker lights and it all looked new not pretty but new lol
I did find out last night that my alternator was over charging at 17v to the battery I fixed that last night so my newest assumption is it blew the switch and the fuses from over charging while I'm changing them I'll definitely clean all the connections for the fuses I know some are a little rusty.
​​​​​​I'll look into the relay kit and get one.
I gotta add when I changed my ignition switch the black and green wire on the connector side charred and burnt the plastic.
*I've ordered the relay kit*

 

I took all the marker lights off and found the passenger rear light was melted and shorted out to each other. Put the old stuff in and it works like a charm.