SA Electrical Help

[infernosg]

I just picked up a clean SA ('79) sight-unseen. I had a dealership local to the seller check it out and they found no issues. However, it has some electrical issues I wasn't expecting as neither the dealership nor the previous owner mentioned them:

1. The tachometer doesn't work. I verified with a timing light all four plugs are getting spark and the resistance across the posts on both igniters is within spec. The gauge isn't getting the engine speed signal and is always displaying the voltage.

2. The "add oil" light is on but the oil level is at the "full" mark on the dipstick. I haven't checked the oil level sensor yet.

3. The "add coolant" light is on but both the radiator and overflow bottle are full. I haven't checked the coolant level sensor yet, but grounding the connector to the negative terminal of the battery doesn't make the light turn off.

4. The "gen" light is on. Voltage at the battery and alternator "B" terminal checks out around 12.25V with the car off. With the ignition on and the car running the voltage is 11.75V at the battery and 11.50V at the alternator. According to the dash voltmeter increasing engine speed increases voltage, although it does show voltage going well past 14V so I don't know how accurate that is. I can't find a 1979 service manual to check the alternator as it appears to be different from the 1980.

I don't think the dealership and seller are lying when they said nothing was wrong when they last had the car. I'm thinking there's something wrong with the charging system that's linked to everything as it seems unlikely all these sensors would fail at once. I can't think of anything that could have failed during the delivery of the car. Am I missing something?