Instrument Lights and Daytime Running Lights Not Working

[Double-A]

I didnt test the switch but last time I did the jumper test (which is the same thing that fixing the wires would do) it had power. If I remember correctly though the switch turned on the headlights and the parking lights but the clearance lights turned on and then went out.. Im pretty sure they arent burnt out because they are new bulbs.

[bd]

The cab roof (clearance) lamps typically are powered off of a headlamp switch terminal that is adjacent to the tail/park lamp connection, or plug into a short brown pigtail off of the headlamp switch.  OE running lamp wiring is brown.  Try the running lamps and headlamps again.  If all the running lamps work except for the clearance lamps, there's an open in the brown wire running up to the clearance lamps or the lamps aren't grounding.

[Double-A]

Ok I got my batteries tested. They are fine it turns out. I started the truck and tried the lights. The headlights work (the front right top one doesn't anymore). But all of the parking lights including the clearance lights dont work.

[bd]

Recheck the fuses.

[Double-A]

The tail/ctsy fuse was blown. I'll have to get a new fuse tomorrow (I don't have any 20amp ones on hand like it had) and I'll report back if it blows it again

[bd]

Now I think you are getting down to the reason the PO hacked the wiring.  You probably have a wire in the running lamp circuit that is bare and touching ground.  A common place for this to occur is where the rear lamp harness passes over the rear axle on the inboard side of the left frame rail, close to the exhaust pipe.  Exhaust heat melts the wire insulation and the wires ground against the frame.  Inspect the rear lamp harness in that area and look for evidence of heat damage.

[Double-A]

Alright sounds like a good start

[bd]

Sooner than later, you should plan on replacing that missing headlamp switch connector.  They are available from  AutoZone,  NAPA,  O'Reillys,  Classic Parts,  etc.



Pick up a 20-amp, auto-reset circuit breaker (image) and attach a couple of 12" 16-gauge leads with insulated alligator clips.  This will make a handy jumper for testing.  Do you have a test light?

Remember this post?

You could save yourself a lot of coin and streamline the troubleshooting process if you temporarily substitute a breaker for the fuse.  Add a 12-volt buzzer across the breaker and you will hear the buzzer every time the breaker pops.  Handy when you are crawling around under the vehicle or are in an awkward position.

[Double-A]

Ok that is an even better plan. I'll have to see if O'Reilly/HD has a buzzer.

[bd]

Look for a buzzer that is compact, lightweight and doesn't use very much current.  A plastic two-prong seatbelt warning buzzer is a good choice if you can find one that isn't expensive.  Best bet might be Radio Shack or similar electronics supply for a small, loud, 12-volt buzzer.

[Double-A]

Alright

[Double-A]

Ok I have the new fuse and will start looking for the bad wire(s) tomorrow. I should mention my brother had to replace the passenger side tail light so maybe that is where an open would be.

[Double-A]

Alright. I checked the areas you described. No wires were burnt, I am guessing because the exhaust pipes were hacked off to before the tires. I did get a picture of the harness where you would hook in trailer lights/electronics. It looks like there are a few splices and loose ends there. I didnt check the replaced taillight but I might do that tomorrow.

Here are pictures of the questionable area, its by the rear bumper close to the trailer hitch. (http://imgur.com/a/S3r47 I used this to maintain quality.)

The first photo shows 2 items circled in red. They look like they were once connected but aren't now? I am not 100% sure.

The second photo has the same things circled in red.
   The purple circle I think is bed sheetmetal to chassis ground (Needs cleaned badly)

   The yellow circle looks like it has been altered because of the electrical tape.

   And finally the black circle is a wire that looks like it was cut by something, but it goes to a license plate light.

[bd]

A)  The rubber connectors circled in red are for dual license plate lights.  It appears that one connects to the trailer plug.
B)  The frame connection circled in purple is a trailer ground.
C)  The taped bundle circled in yellow is after-factory splices into the OE rear lamp harness for the trailer lights.  I agree that they at least should be unwrapped and inspected.  In addition, inspect the trailer cord plug for muck and shorts.
D)  I don't see the "black circle" to which you refer, but the black arrow points to what I suppose is the trailer brake supply from the dash mounted controller.

Note that there are "Scotch Locks" clipped to a few of the wires above the frame rail.  It is prudent to suspect any wiring that incorporates Scotch Locks.  Scotch Locks are not intended for use in unprotected environments exposed to weather.  However, although intact Scotch Locks will not cause short circuits and therefore are not the immediate problem of blowing the fuse, they commonly result in intermittent and permanent open circuits. 

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You should isolate the running lamp wiring into zones to try and narrow the location of the short circuit causing the tail lamp fuse to blow.  You can rule out the instrument cluster wiring, since the 5-amp instrument lamps fuse is unaffected.  Isolate the roof clearance lamps, from the forward lamps, from the rear lamps, in stages.  You can do this without cutting wires by following the subsequent procedure.

Zone 1:  The brown wire feed to the roof clearance lamps should connect directly to the headlamp switch or plug into a short pigtail within about three inches of the switch.  Unplug the clearance lamp wire to see if the tail fuse stops blowing.  If the fuse stops blowing, the short is in the clearance lamp feed or roof lamps.

Zone 2:  If the problem persists, unplug the bulkhead connector from the engine side of the firewall and separate the rear lamp connector (the leftmost third of the bulkhead connector that is closest to the left fender and contains only four wires: yellow, light green, dark green and brown) from the main connector.  This step completely disconnects the rear lamps from power.  Reconnect the main bulkhead connector to the firewall socket and recheck the lights for blowing the tail lamp fuse.  If the fuse stops blowing, the short is somewhere in the rear lamp harness or rear lamps. 

Zone 3:  If the fuse continues to blow, unplug the bulkhead connector again and separate the left half (driver side) from the right half.  Reconnect the right half of the bulkhead connector to nthe firewall socket and recheck for blowing the tail lamp fuse.  If the fuse stops blowing, the short circuit is in the forward lamp wiring or lamps.

Zone 4:  If the problem persists, the short is in the running lamp wiring under the dash between the headlamp switch and bulkhead connector, or between the headlamp switch and instrument lamps fuse in the fuse block.

[Double-A]

This is just a little update.. I plugged in my little auto reset tester and the parking/clearance lights turned on with no trouble and didn't set off the breaker.