Coolent/GEN/Oil Light
 

So all my lights went on yesterday and my tach turned into a volt meter. Thought my belt snapped but it was still attached.

If i rev the engine it says its charging, but doesn't charge at idle.

Is it safe to assume its the regulator that went bad? I bought a cheap one from rockauto about a year ago.

Is there a way to test the regulator? Anything else to consider?

I've been driving the car pretty hard these days, lots of 1-2 hour drives on the highway.

Hey, new guy - search is now simpler than ever...
 

Scroll down, and there's a good start. Once you do some reading on your own (*faster and gets you help right now...), you'll have more information with which to frame your question.
https://cimg2.ibsrv.net/gimg/www.rx7...bdaf8aee4a.jpg

I like the site specific search using Google, limits restult to the first gen section, easy to do like this, just type into a Google box:--

So I replaced the external regulator and that seems to have solved the issue of the battery not charging. However the Tach is still acting as a volt meter. Anything I should check next?

Experimenting with suggestions from this thread, as i have a very early 79 model. The manufacture plate in the inside of the door actually says its a 78.

https://www.rx7club.com/1st-generati...-meter-914537/

Your door tag indicates the date of manufacture, not necessarily the model year. Mazda actually began building JDM cars in January of 78, even though they did not officially even launch them until March in their own home market. That same March, they began producing the 5000 VIN series for export to the North American market. However in the US, the first official model year was 1979. So even though a North American car can have a build date of March - December of 78, they were sold and registered as 79's.

I do however believe that some cars may have been brought in and sold early enough that they were actually registered as 78's. It really doesn't matter much now as all the cars made up to Jun of 79 (when they switched to 80 production) are considered 79's here in the US.

In Japan its slightly different. The cars were introduced there as Savannah Rx-7's and JDM cars built and sold in 78 are known as 78 Savannah's. Although Mazda made a bunch of small running changes / modifications that first model year, their 79 factory manuals cover all the cars first produced.

those with the '78 build date still have the hood prop on the passenger side. the date on the one i had was 8/78.

Pretty much yes. The hood prop was one of those running changes that took place at the end of 78. By Jan of 79, the 5000 series VIN cars had their hood props re-located to the left side to match the drivers location. No more walking around the car just to open the hood.

First, the hood prop is annoyingly on the right side of the car.

Second, the wiring is so fucked in this car, so many repairs over the years, wires have been spliced together, electrical tape everywhere.

What should I do? Should I just start going through every wire and start taking them apart, clean them up and reconnect them? How deep should I dig into the wiring harness without compromising the car?

From what I have read, the Tach functioning as a volt meter could be so many things.

Where can I look at the check choke relay?

Great resource for manuals.

Foxed.ca

Ahaha, every electrical issue thread always dies with someone linking the electrical manual.

Definitely not my skill set, guess I'll bring it in to someone.

Just offering a resource based on your question. It's hard for us to know what to do without seeing what someone else has mucked with.