n8r

Turned my '79 on today and was treated to the check engine/generator/oil lights staying on and the tachometer registering approximately 5,000RPM at idle. The car seems to be running just fine. I have the stock original shitty iginition system. From a quick survery of the engine bay everything looks to be in good working order. Any thoughts?

Kentetsu

If the alternator belt is still there, then you'd better start checking your grounds...

Clean all battery connections at both ends for starters. Good luck!

n8r

bumping for additional ideas...

TurboSE

I second the grounds! Check your grounds and igniter connectors

gsl-se addict

iTrader: (3)

I'm with Kentetsu on this. The car is a '79 so it has the combination tach/voltmeter. Your tach isn't off. It is stuck reading volts still like when you turn on the car without starting. The fact that the warning lights stay on is a good indication that the alt is not charging.

Your alt is either not charging (broken belt), bad wiring (alt plug disconnected), or the relay for the alt is bad/disconnected. Because of one of these things, the alt check relay/warning lights do not know that the engine is running, so it stays lit up the same way as with just the key on and not running.

Kent

Yark79

If the voltage regulator goes bad, it will cause the tach to stay in the voltmeter mode. I don't know about the warning lights, but a new regulator might fix that too. I've replaced my voltage regulator twice. The first time it died, the alt quit charging so my battery died, after replacing the battery, the tach got stuck in the voltmeter mode. The second time I had to replace the regulator because some switch inside it had gone bad and caused the alt to drain my battery when parked.

n8r

Thanks for the additional replies. I have gone through the entire engine bay to see if anything looks like it has been disconnected - it all looks good. I was not able to find the location of the voltage regulator in the Mazda repair manual - but I looked the part up online:
http://www.partsamerica.com/ProductD...pe=204&ptset=C

Is this picture correct? If so it appears that it is mounted on the drivers side quarter panel back near the master brake cylinder. Is there any sort of test I can do to see if the regulator is functioning properly?

EDIT: Also to add - when I use my turn signal the tach bounces with the beat of the turn signal - no clue if that gives anyone any additional ideas...

Yark79

Thats the right pic and location of the voltage regulator. The tach bouncing is the voltage being drawn to powere the turn signals. So its deffinately reading volts and not just out of wack. I don't know of any way to check the regulator, but I would bet that it is your problem. When my tach got stuck on reading volts, the problem was immediately fixed when I changed the regulator. Of course, you don't really NEED a tach, so if you don't want to spend the money on a new regulator, you don't necessarily have to buy one.

n8r

Thanks for the help, I think I'll order one up and hopefully that will solve the problem.

Yark79

You may want to make sure that the new regulator has the right number of wires coming out of it. The second one I installed was missing like one wire, but I didn't seem to matter not having it. I got it at Advance.

n8r

I replaced the regulator and it made no difference - fortunately replacing the alternator seems to have fixed the problem. It seems that the tach going nuts was a result of a low power situation but the battery wasn't getting drained until the alt failed a little more. I guess I should have tested the alt before I bought the regulator - no big deal.

fishbulb95

hey atleast its not as bad as my friends speedometer, accurate to about 25 mph, then shoots up to 85 and starts bouncing around (82 GS)