Replacing rear wiring to lights/ gas tank

[Crawdad]

Whenever I filled up my bronco the fuel guage only went up to half way. I asked a mechanic to fix this issue last week while the bonco was in the shop. He told me the wiring harness had been spliced in several areas and the wire couldn't carry the right resistance or ohms.

I was wondering if any of yaw had this problem. JBG has a rear wiring harness (http://broncograveyard.com/bronco/i-18042-chassis-and-taillight-harness-1970-77.html) but is it a direct replacement for the lights AND gas tank? Has anyone used this harness? I would pay the $160 vs the $400 my mechanic quoted me for parts and labor. Thx guys!

 

[brianstrange]

I would measure resistance at the sender, before replacing anything. I believe the range is 10-70 ohms. If you have that range (measured empty and full), measure again at the firewall connector. Also, check for bad grounds at the tank! It would take many splices to have that type of impact. If your harness is that bad, I would spend $20-$30 on wire & materials (solder & heat shrink), and repair your harness properly. $400 sounds like you need a new mechanic. This is a 2 hour job at most!

 

[Bartonatl]

Here is what I'm about to try. My wires are cut and spliced all over too, so I went to home depot and found a Sprinkler wire that has 7 wires in one sheath. I got a 25' role for around $20. It will make for a really clean installation. I do have an Aux tank so at that point I'm going to have to cut the sheeth and pull one of the wires out to connect to that sending unit. Should make a clean, cheap alternative. This is definately a do-it-yourself job.

 

[Viperwolf1]

You can use a 4-pin flat trailer wiring harness. It even has the correct connector for the rear lights.

 

[Crawdad]

I would measure resistance at the sender, before replacing anything. I believe the range is 10-70 ohms. If you have that range (measured empty and full), measure again at the firewall connector. Also, check for bad grounds at the tank! It would take many splices to have that type of impact. If your harness is that bad, I would spend $20-$30 on wire & materials (solder & heat shrink), and repair your harness properly. $400 sounds like you need a new mechanic. This is a 2 hour job at most!

Yeah he said it would be a four hour job plus parts. I figured he was talking about re-wiring it all by hand. Thats why I was wondering on the wiring harness JBG sells. If that piece does the entire rear half of my bronco I'll pay the $160 and be done with it in one hour. The PO (my dad) has done a lot of splicing in the front by soldering & heat shrink. But the color coded wires spliced with one color wires get me all confused. I tend to like it simple and neat. I think I saw a piece of speaker wire going back there and I don't have a radio in my bronco!!!

 

[Bartonatl]

You can use a 4-pin flat trailer wiring harness. It even has the correct connector for the rear lights.

I'm glad you said that. I need to add that plug for trailer lights. How many wires would he need? four light, a common and 1 fuel tank = 6 wires headed to the back?

 

[Viperwolf1]

I'm glad you said that. I need to add that plug for trailer lights. How many wires would he need? four light, a common and 1 fuel tank = 6 wires headed to the back?

http://classicbroncos.com/tech/plug-in-trailer-harness

Four light wires, left turn/brake, right turn/brake, park, and backup lights. The main tank wire breaks out before getting to the rear connector so it can be run separately. Grounding is done at the frame.