wiring fiasco

[abe]

As some of you know my new 1970 F-350 was giving me some electrical wiring problems. There were some wires that were chewed off by little critters. The PO instead of connecting those wires, rewired the brake/tail/turn and the bed marker lights.

First my marker lights did not work when it rained, then they came on when I applied the brakes, then they stopped working altogether. I was under the truck looking for a loose wire, and then I noticed my turn signals did not work when the lights were on. Then the turn signals did not work at all. Then the brake lights did not work.... So I lost every thing back of the cab, including the back up lights.

Messing with it today: Could find no loose wires. Then I noticed where the PO had grounded several wires. He had about 3 wires from taillights grounded at a stake pocket. I took it off got sandpaper and steel wool and got the rust off and .... all marker, and taillights work!


But the brake and TS do not work! Any advice as to where to look? Also are there fuses under the dash on the passenger side or is there just a relay. The fuses on the driver side all look good, besides I don;t think any of them are for brakes or TS. I think I used to hear a click on the passenger side when I applied the brake. what was this? I don't hear the click anymore.

any help on where I should start?

[abe]

I failed to mention that the turnsignals do not work in front either. I replaced the flasher with 2 others I had and no change...

[basketcase0302]

Abe,
It sounds to me that you possibly have multiple PO "hacked" issues here. To start with here's the wiring for the cab lights:

The relay and circuit breaker for them is behind the glove box mounted to the right side on the sheet metal there. You should not hear the relay or circuit breaker click when applying your brakes.

Sorry, I'll be back later...

[abe]

Thanks, Jeff. I have seen that diagram here at this site. The wiring diagrams have been a great help. My marker lights and taillights are working. It was a grounding issue.

I will double check my fuses since there is a fuse for Backup lights and turnsignal and a fuse for Emergency and stop lights. Those are the things that are not working right now...

Just out of curiosity: what is the purpose of the relay or circuit breaker? This is new to me as my '54 F-100 is much simpler to troubleshoot wiring problems...

[abe]

Also, let me add this: the PO put in a 1971 steering column and wheel when he added power steering. Are the wires coming out of the steering column the same color for 1970 as they were in 1971?

[flyboy2610]

Sounds like the turn signal switch might be toast. Your brake lights route through that switch. In fact, your rear turn signals are just your brake lights flashing on and off.

[abe]

Update: after messing with the truck today... I took out the fuses to check them, cleaned them up with sandpaper, put them back in, no change...

Later this evening, I had to move the truck so I tried the turn signals before I started the truck. Turned the key to the left to Aux to try the TS. They did not work. I sat there in thought with the key and TS still on and after a few seconds they started working!!

But, still no brake lights! Here is my thinking: it rained the last 2 nights. Yesterday was cloudy all day. Today it was warm and sunny. Did some moisture get into a junction and now only dried out, thus allowing a free flow of electricity? The PO did some funky wiring: in some spots he used an heavy duty orange extension cord; other places he used household wiring. He joined wires together with wire nuts!! Is moisture my problem?