Electric issue. Nothing works unless ignition is on/acc

We’re struggling to solve a wiring problem…we purchased our 2001 Sequoia in December and it came this way. Most of the electrics that should work with the ignition switch off don’t work, but they all work once the ignition is switched on. E.g power locks, interior lights, clock/radio. We’ve checked all the fuses and seem fine. Got a brand new battery. Not sure if it could be the ignition switch itself. Our car never came with fobs for remote door lock/unlock, so I don’t know if maybe previous owner bypassed something like the immobilizer? Previous owner added an after-market towing brake line thing (“Spectrum” brake control), so maybe that’s interfering with something? There is an unconnected wire floating about in the engine bay - it looks like someone added it there but we don’t know what it is for. Looks like it connects directly to the battery and I’m guessing it’s for the brake control thingy. I’m wondering it if it is typical for owners of these cars to disconnect things or bypass things in case of parasitic battery drains and if so, what are the typical culprits?

 

Welcome to the forum.

Here are Sequoia wiring diagrams if it helps.
Ultimate SEQUOIA Wiring Diagrams Collection | Toyota Tundra Forum

It can help you track down where circuits get power from the battery.

This is the main power source diagrams



Me guessing at stuff won't help so hopefully someone more knowledgeable will chime in.
@shifty` knows a lot about Gen 1 Tundras, perhaps he can help when he has some time..

Good luck.

 

Thank you! We did find the wiring diagrams (which led us to this forum!). Husband is a sparky, so hopefully he can interpret the wiring diagrams…..they look crazy complicated to me, like rocket science or neurosurgery complicated… If we figure it out, I’ll follow up with an update and hopefully help someone else out with similar problem….