Hello-
I've been having trouble with the tach not working and the alternator not charging on my '93--just an intermittent problem. Some guys on here suggested checking the crank sensor gap and wiring, which my husband did and they seemed okay. But lately every time I start it, it won't charge and the tach won't start working until it is COMPLETELY warmed up and the thermostat opens (and then if it was cold enough for the grids to cycle when I started it, they'll cycle, even though the engine's warm.) If I shut it off briefly and start it again, it's fine, but if it cools off, it's the same thing again.
Any ideas? Is the PCM shot? Thanks.

 

Could very well be the PCM. My tach lead wouldn't work until I replaced the PCM. The charging system is controlled by the PCM also. Try the AC to see if it works as this also quits when the PCM craps out.