78 SR5 Sport Coupe electrical issues

[SGAslider]

I have a 78 SR5 sport coupe (TE-51) that runs great. Replaced the alternator over the weekend and drove it to work today (45 miles one way). Drive in was great. When I started the car to drive home, I got a charge lite, no tach, no oil pressure indicator, and no oil temp indicator.

I got the car home and put a voltmeter on it, thinking I had a bad alternator out of the box. Nope - altermator was putting 14.2-14.5 volts to the battery, but still same issue as above.

I am more of a mechanical mechanic, electrical system are NOT me. I suspect the voltage regualtor but not sure. Ideas?

[SGAslider]

Update - it was not the voltage regulator.

I have used my multimeter to eliminate a lot of stuff. I have voltage through the fuse box and past a fusible link going to the instruments. I have removed the instrument clusters and done a few checks. I have continuity from the ground wire in the plugs to the frame. I have continuity between the plugs on the same wire (red/blue). So, I am going to look elsewhere.

The circuit off the main fuse has four other circuits - instruments, rear defog, back-up lights, seatbealts. I feel like I have checked the instruments and found them good. I disconnected the rear defog switch, but that did not solve the issue. So....

What if the power (hot) wire going to one of these other circuits was broken and grounding out. Would (Could) that take out the whole circuit?

[WhoaMan]

May I suggest this, even though it appears you have power on both sides of each of the fuses.... this generation of toyotas have problems with corrosion in the fuse panel. pull all the fuses and carefully brush the contacts on the fuse holders... and gently squeeze the holders together to get a better fit. If memory serves... the fuse that will describe the problem you are having is on the left side of the fuse panel, second from the bottom (above the tiny fuse for the radio). I hope this helps

[SGAslider]

Thanks, Whoaman. I will check that out.

Since my last post, I have removed all the dash components and checked continuity on the red/blue wires and the grounds. All checked good. I disconnected the rear defog switch, found the seat belt computer and checked those wires, and visually examined the wires for the back up switch on the transmission. I also checked the back up light bulbs. No continuity issues with any of these....

Whoaman, I will check the fuse box, but I have found some other interesting things to bounce off y'all.

There is one red/blue wire that comes out of the fuse box off the rear defog fuse. It has a fusible link, then goes to a huge connector 'box' where two (2) wiring harnesses come out. One of those wiring harnesses has two (2) separate red/blue wires. One wire has continuity to the instrment cluster and the other has continuity to the seat belt computer. The defog connector also has a strange pairing of wires. It has three prongs - a ground, a single red/blue wire (which may be power in) and a double redblue wire (which may be power out to two (2) separate circuits).

Does this make sense to anyone? Could this somehow be related to my problem.

Let me also clarify where I am trying to get to - this is NOT a show car. It is a 33 year old daily driver. If I find a bad component - such as the rear defog switch or the seatbelt computer, I will leave it disconnected. But , I REALLY want to have my other instruments working and my charge light to go out.