Positive Wire from battery to fuse box? No Power

[GetBoost]

Summary: Short drive to work the other day and every time I touch the brakes my cd player and A/F gauge restarts. That night I go to leave and nothing works. No power locks, lights, ignition, etc. Check the battery and the neg connector is completely loose. I tighten everything and try to jump the car, but still nothing, not even dome lights. Took the battery to advance it tested good and to recharge. After the recharge it tested bad. Purchased a new battery happy that it was the problem, but still no power. All the fuses checked out, and all of the connections are tight. From my searching it appears the wire from the positive side to the fuse box controls all power. Even though it is tight, it does look brittle.

Question: The wire goes from one thicker wire to two smaller white wires. The thicker wire needs to be cut off, but then the wires will be too short. What is the best way to extend these wires? Can I split the two white wires and extend separately to the positive terminal? Solder, butt connectors, or what?

It's tax season, the supra is stuck at work and I am limited on time. I apologize for starting a new thread as I did find several with this issue, but they typically wandered into other discussions. Thanks for any help.

John

 

[Kckazdude]

I am working from memory here but if I am not mistaken there is the large wire that goes from the battery to the starter and then another wire from battery to under-hood fuse box. My suggestion would be to go to NAPA and get these part #'s.
728249 battery terminal
781147 bat-starter
781144 bat-fusebox

That should end your power supply problems.

 

[GetBoost]

Thanks for the quick response. I was thinking the two white wires split and went two different places. The engine wiring harness is only a couple years old and was expensive so I did not want to cut the loom to trace the white wires until I had a better understanding that is what it was. The battery terminal and the starter cable have been replaced. So I should be able to remove the white wires completly and replace with 781144 bat-fusebox cable. Does it just bolt under the fusebox?

 

[akito]

Check the 12mm bolt for the main harness at the intake manifold. I had this exact problem once and after looking at everything it was this 12mm that didn't want to stay tighten and the whole car would not have any power at all.

 

[GetBoost]

Update: I extended the white cable from the fuse box with 6 gauge wire from lowes, still had no power. Replaced the battery connectors and scraped the ground contacts, and the car came back to life. Hindsight I should have changed the connectors first considering it was the loose negative terminal that was the obvious sign when the problem started. I thought the connection was good once I tightened it though. Thanks for everyone's help!