79 SA idiot lights on and tach over 6000 at idle
 

So while preparing to leave last weeks meet I start the car ... and as the title reads all the idiot lights were on and tach read over 6k rpms ... at idle .... drove home they were all still on ...

So in an effort to narrow down and knowing the extenal voltage regulator hooks up to the volt meter cicuit which lives in the center of the tach I unhook the regulator ... lights went out and tach started working properly again

Ideas what the heck is going on ???

thanks guys

Is your regulator ok? Theres ways to test it I think. Haven't dealt with a regulator in yeeeaars
tho and never with an rx7 one.

Three possibilities come to mind:

1) regulator relay stuck, possibly outputting higher-than-normal voltage. Don't run it that way too long or you may damage something. I'd give this one highest odds of being right.

2) The 'check' relay or a connection for it is failing. This is the dingus that turns on the idiot lights to test them when you first turn the key on, and also tells the tach to display voltage when the engine isn't running. Mounts above and to the rear of the left fenderwell right near the regulator, usually is stamped 'CHECK RELAY' on top.

3) Loose or bad connection to one of the above.

I don't know much about SA's but I would think the tach signal comes from the trailing ignition system like a FB so if its not working the cluster may not recognize the engine running therefore keeping the idiot lights on and the voltage side of the tach online.

I believe when the regulator fails the idiot light will light up but since the voltmeter is also on the same circuit that will override the tach even when running. Could be a bad connection but unlike what divindriver said I believe the circuitry for the system check is actually located within the regulator, at least thats how it was on my 79. No extra relay external to the regulator. Something as simple as a bad fuse on that circuit will set off the light though. I had this problem with my car when a fuse actually fell apart.

I re-checked the diagrams - - the Check Relay was added in 80 when the alts went to internal regulation. 79's didn't have them; the function is inside the Regulator as 85RP said.

Thet points more precisely to the voltage regulator module.

Yes, I'd suspect the voltage regulator first. I keep a couple spares on hand to have just in case. One is the newer solide state version that I keep as my "test queen". A known good unit that I use to pop in and quickly isolate the problem. That should be your problem.

If not that, look at the alternator. I just had a car that when starting, the tach would jump up and read high untill you blipped the throttle and it setteled down to normal. Finially, it started reading 6K all the time (no false idiot lights) . The problem turned out to be a bad rectifier inside the alternator. Revs are back to normal now.

Idk why ur keeping that low 55amp alternator since ur SA is not stock. Just upgrade to Fc alternator and the connect a 12v to the upper male terminal on the 2-wire pigtail.

this issue is kinda a right of passage for us rx owners.
btw mine fixed itself

The service manual should gaps , air gaps and such ... but the one I had was a solid state style so it was a sealed unit

DD will catch ya on the other post

could maybe see that if it was just the alt light but it was all of them ...
ignition is working ... have been following another issue ... see detonation thread

the thing that go tme was "all" the idiot lights were on ... so wasn't sure if an igntion switch issue ...

sometimes having our year cars the 79 & 80 and their little quirks and differances aren't so cool ... regulator sounded more and more the culprit, had to forget about it being 2 years old and driven about 6k miles aka pretty dayum new

Alternator was checked and appeared ok .... was another part just a couple years old

Wacky I beleive the 79 was a 37 amp alt, while my car my not look stock I can make it so over a weekend with engine, rims etc etc I potentially have 2 cars in one lol ... I'd like to upgrade the alternator the question how to incorporate it without hacking the harness ... everything I've done to my car can relatively be easily undone

see your from NY how big of a hammer did you use? lol

(born and raised in NYC myself so no offense intended)



Ok so after taking all of your advice ... we, Easy_E with Black Halo Racing (a rotary shop in the PHX area) who happen to be in town and I went through the sytem last night .... we would get a spark when the regulator was being unplugged .... but it ran smoother without the reg hooked up with no idiot lights and tach working .... so we continued with checking fuses, they were good and in place as my big feet sometimes brush the fuseblock .... tested the circuits .... tested the alternator .... so we were coming to the conclusion had to be the voltage regulator ....

had a known bad regulator .... but where the hell were we going to find a good one after midnight ... I had to use the car to get to work in the morning as the pos daily has a head gasket issue ... piston junker with 84k miles ... but back to a regulator for the SA ... So I found myself where many of you I am sure have ... hands on hips late in the evening and saying to yourself wtf? ... then it caught my eye ... across the garage on a self behind some filters ... could it be? ... yes!!!! the NOS regulator I had not remembered seeing since moving the family to the current house .... popped that baby in ... no idiot lights and tach reading properly ... woooohoooo

So what was becoming a frustrating issue was made hugely better by having guys like you to pick the brains of ... and one of the rotary owner side effects ... being a parts hoarder lol


thanks guys

You wont need to hack the orig engine harness. All you need is a 12v to trigger the fc alternator field terminal which can be sourced from any ignition wire.

Unfortunately, eletronic things can go bad at any time w/o any notice or reason or many miles on the clock. The 79 alternator is a 55 amp, or at least should be.

opps maybe I mis spoke on the amps lol

Totally, over 25 years in the parts industry and I've seen them myself including out of box defects ... just leaned towards it being an oldercar wring problem and my scrambled brain was going in circles :lol:

thanks again all that chimed in!!