So I just bought a 1990 GXL that was sitting for a few years with "Overheating problems". Figured out the fuel pump was receiving voltage but not responding, so I replaced it and bam, car works like a charm.

One major problem: The warning lights flash on and off. All of them come on at the same time at random times while driving, and sometimes flash or disappear. Some drives I don't see them at all, other times they're on constantly. What's up? The lights come on and go off in unison, so I know they aren't working properly.

I googled around and read some stuff that suggested it was an alternator issue, but the alternator and belt seem to be working fine so I don't think that's the case. Is it just crappy wiring behind the warning light plate? I'm baffled.

 

If all of them go on and off (not just the bat charge light), it will most likely be the awesome soldering job mazda did on our cars. Running new solder on the idiot light board or getting a new one will fix the problem.

Check the wiring for the idiot cluster, if it's good then you know what to do.

 

two things about the Idiot light cluster,.
If it flashes all the lights.it could be cold solder joints in teh cluster OR the alternator telling ya it is gonna Dump out on ya.(check the Belt Tension)
Check the output voltage of the alternator,If you have a Volt meter,keep an eye on it.That will tell you whether or not the Alternator is going,
That would only leave the Idiot light cluster problem to be cold solder joints.