i did a 3k takeoff.as i started down the hill i hit the brakes and all of a sudden my low coolant, gen, and low oil lights come on and the tac goes to 5.5k. thinking it stalled due to my fuel problems i try to restart with a grind sound, pull into the station and it is idling still even though the tac shows 5.5k. so i freak and look at the engine bay, no oil or coolant drain. also the belts started squealing. so i drive it back up the hill squealing, park it get out and take a thorough look. turns out the battery didn't have the hold down on it and fell into the distributor area. i have checked all the wiring connections in the area and haven't found anything. i have noticed that the car reads about 5.5 on the tac with the car in the on position(not started). so it seems the tac is seeing voltage and not converting to the rpm. it does rise with the engine still. the coolant, gen and oil lights still stay on. i think thats about it. i need this car up and running by the autox this weekend. sos, mayday.

 

I think on a 79 the tach is supposed to jump up (with the key off though), since the volt gauge is part of the tach.

I'd check the alternator, sometimes all the warning lights coming on is from that.

 

Either one of 2 things have happened, the wiring or plug from the alt isnt telling the car its charging, or the alt isnt charging... The 5.5 is telling you voltage, look around the numbers closer it has Volts in the area of the numbers too.. Alt could be bad too.

 

thats what i thought at first but it seems that the alt ios working properly,
it looks like a huge 2nd gen alt,
its definetly throwing out some juice,

also when he presses the gas the tach still functions,
it just starts at 5,500 at idle and rises like its suposed to but reads 5,500 rpm to high,

when he starts it drops down like its getting ready to work but then just jumps up to 5,500

and no his car is not really idleing at 5,500 rpm

we went through all the possible wires and connectors that it could have came in contact with and even ones it couldnt hit,

we found nothing,and even i "a rotary techie for 4 yrs" couldnt figure it out.

 

I had this sort of thing happen when my alternator started to take a crap.

I was driving and allofasudden all the warning lights came on and the tach was reading voltage instead of engine RPM. I found that by screwing around with the key (shutting car off and on while rolling down the road) it would go back to normal.

That was the night I drove 10 or so miles at almost midnight with the lights off... going about 80-85mph, trying to get home before the battery died. I ALMOST made it Coasted in to an all-night gas station, swapped alternators under the lights, hung out until someone gave me a jump, then went home. Fun times

 

Sounds like the alt is going bad, not putting out enough/any juice at idle

 

Are the 79s internally or externally regulated?

 

when the car is not runnig "after the car has ran for a couple of minutes"
so i really dont think its the alt,

we will have to go the local auto parts place tommorow and have them test it.

 

If you had a spare alternator with you, why didn't you just stop and swap it out before your battery died?

 

no light.... oh, and why not push start it????

 

English anyone?

 

Either your battery bashed a component, or shorted and blew a component when it tipped over.
(Did you check everthing about the trailing ignitor...Right down to swapping a good one in or switching it with the leading one?)

I'm unfamiliar with the earlier models. But logic tells me there's some relay that switches the tach from voltmeter mode off so that the signal from the trailing ignitor can have the gauge all to itself. Find that relay, and I think you'll find the problem.

betchabetchabetcha...

 

They have external regulators

 

it looks as though the battery hit the dizzy as there is a mark from the corner of the battery on the side. we've also started the car quite a few times while we fiddled and searched. that would lead me to believe it isn't the alt as the starter should start slugging with a draining battery. we're going to switch it out with the se's alt just to make sure. i checked the dizzy out and everything appears visually ok. also the 79 actually runs the tack off of the leading coil. when the battery fell it seems it pulled taught on the leading coil. could this do internal damage to the coil and cause the lights etc?

 

David you know where the choke and check relay is right?

Thats the relay that puts the dash lights out, if you got a DVM and alt shows a higher voltage running than when the car is off. The alt is probally OK. Check that relay, could have bad contacts....

 

check your distributor. My batteryu used to slide around and it struck the distributor and the rotor broke apart. I had trailing on only one rotor and the tach was fucked.

 

pulled the dizzy cap off and everything appeared ok. one of the points is slightly off but that looks like a previous problem. it runs so i figured the dizzy is ok.

 

Because it was almost midnight.

Actually it wasn't a spare alternator... I'd swapped a Subaru (higher output) alternator on that morning at work (tested it to over 70 amps) and still had the old one in the car. I had two Subaru alternators, one good one bad, so I guess I put the bad one on. I wanted to TRY to make it home, because I realized something was wrong when I noticed the headlights were very dim and orangey. It was very cold out, and I didn't want to be stranded on the side of the road.

Interestingly the gas station was a good place to be... very bright lights made it like working in daytime, and they had a free-refills coffee machine

 

Sterling.... the early models use the leading ignition for the tach signal. I think that's how they determine whether it's a tach or a voltmeter. Most tachs will act like voltmeters, all Mazda had to do was make the tach work over a range that coincided with the normal voltage range of the electrical system. Voila... when it gets a straight DC signal, it's a voltmeter, and when it gets a square wave, it's a tach.

At least, that's what I think... I do know that I tried installing my MSD per Paul Yaw's instructions (go off of pickup coil) but when I did that there was no tach signal, since the tach gets its signal from the leading coil. The engine would run, but the tach was still in voltmeter mode because it wasn't getting any signal. (Couldn't swap the tach signal to the trailing, because trailing ignition is not used full-time on the SA's. Ended up installing it the way he said to absolutely not install it, and it worked just peachy!

 

ok lunch update. fired it up at lunch. when i would rev it up it would switch over and be fine. the tach would show right and my idiot lights would go away. as soon as it would near idle BAM back to reading voltage and idiot lights. so we have this se alt but since it seems they put a 2nd gen alt on mine i have the plug for the second gen alt. now which wire goes where on the 1st gen plug? and does this correspond with the problem being the alt?