Please help me figure out this mess - Rear electrical
 

82' gs
So, I get no readings on my fuel gauge so I decided to take some time to check on the rear end electrical situation. Got the rear trim bits of only to find a serious WTF moment. It involves a small gel cell battery and speaker wire connected by twisting it then warping it in electrical tape:
http://picturemessaging.rogers.com/m...mZ2PYPLLlY78rx
It has a mess of wires heading to the hatch and fuel tank door electrical unlockers. I know the fuel door doesn't open when i push the button, but cant remember if the same goes for the hatch. It's also running 3 wires to the front of the car. It's raining so I didn't want to take out the entire insides to see where they go today. It will have to happen eventually as if this is the kind of work that's been done to her, there are probably worse surprises in store.
Anybody have a grasp on what they were trying to do here? How I can undo it? How I can do it wright? Also, tips on getting my sender to work (common reasons why it's broken would be great) would also make my day.
Thanks guys and sorry for the cell phone pictures, I'm saving up for suspension bits so getting a real camera is on hold.

Security system?

First I don't see any pictures... :(

Second, it could be a security system or they're attempt to start a separate stereo system?

I attached the image for better viewing of the chaos.
A security system that pops open the gas door? That doesn't make sense to me. I checked again and the speaker wires are the only wires attached to the gas door, so maybe an attempted repair?

Mad Max's Self-Destruct Alarm System?

Only good news is, it doesn't seem to be hooked to the stock wiring, so you can start carefully removing it.

On the fuel gauge, most-common failure is a failed tank sender resistive element. 2nd-most common is probably corroded/disconnected connections or ground. Third is a bad gauge.

#2 is the least expensive to deal with, and so it's a good place to start.

Wait... the speaker wires are connected to the gas door?

yeah. Not in the these wires should go to a speaker kind of way, but in the these wires were designed to be used for speakers but are not in this creation. Apparently going out and getting proper gauged wire was to difficult for this fool.

And it's very much not hooked into the main system.

I do have a bunch of unused connectors in the back that are coming from the main system. I don't have a rear wiper, so that accounts for some. Does anybody know how many extra connectors i should have hanging out from the harness?

The more I look into the more this thing need a complete redux.

Maybe be a power door lock kit?

Why a seperate battery then? :scratch:

I'm suggesting that is the control module, not a battery.

Maybe it was supposed to sense if someone opened the gas door to steal the gasoline and set off an alarm? This was during the last fuel crisis I suppose?

I did say this was a gel cell battery right? For good measure, it's a battery, not a control module. I'll have to trace those 3 wires down to see whats what.

And that fuel crisis peaked in 81, the year before it existed. Also probably not a concern, our fuel doors have locks on them remember?

Connectors in the harness, staring behind the seat would be, amps, cruise control, rear window wiper and heater, antenna, fuel/hatch release, speakers, tail lights, back up lights and license plate lights.