Strange battery light/possible cluster failure?

[Senseirice]

Hey everyone! New to this forum and I'm looking to see if I can get some insight on a problem with my new to me '84 eagle as my google searches haven't turned up anything. I recently picked up an 84 eagle sedan with the 4.2 about two weeks ago and I've been driving basically since. Since I purchased the car the clock in the cluster didn't work and the speedometer is way slow despite the car being on factory tires. The temp gauge also didn't work when I purchased the car but I put in a new sender and that seemed to remedy the problem. Anyways I was driving it last Friday when I noticed the battery light faintly glowing, I made it home and decided to look at the car the next day considering it was about 9pm at night. The next morning I started the car with the light still faintly glowing and it got a tad brighter with rpm. I put a multimeter on the battery and saw 11.9 volts so I put a reman alternator in it and the light was still on but dim. I then noticed the positive wire that goes from the solenoid to the alternator was broken so I soldered it back together and it seemed fine after that. This morning I started the car and the battery light was on nice and bright, I put my multimeter on the battery and it had 14.4 volts. I shut the car off then it wouldn't start. I screwed around with it for a while, got the battery tested and it was perfect, tested the grounds and positive cables and it all looked good. I bypassed the solenoid with some pliers to see if the starter would turn and it did. I tried to start the car again and it fired right up so I thought "that's odd" I also noticed the battery light was out. I gave it some revs and the battery light came back on nice and bright. I unplugged the battery and the car didn't die and I drove it around town for half an hour or so and had no problems with the car loosing power and dying. I did notice that now the temp gauge won't go above the cold line and the fuel gauge won't move from 3/4s of a tank. I also noticed none of the idiot lights come on except the battery light which only comes on with the car running and after you give it some gas. Could the cluster just be bad or is there some other wild electrical nightmare plaguing my car? I'll be honest and say I left for vacation tonight and probably won't be able to mess with the car much until Monday night so maybe I should've waited to ask this but it's just scratching at my brain and it really bugging me. I'm sorry about the wall of text too but any help is greatly appreciated!

[vangremlin]

Congrats on your new Eagle and welcome to the Den.

I can't really speak to the overall problems but sounds like you're doing a good job of trouble shooting.  I will comment on a couple of things.  It's not unusual for the temp gauge to ride on the cold line, both my Eagles do that, most seem to run on the cool side.  You can test the fuel gauge by grounding the wire that attaches to the sending unit at the gas tank while you have the key in the "on" position, that should tell you if there is something wrong with the gauge.  You can do the same with the temp gauge.

Good luck and keep at it, you'll really enjoy driving the Eagle!

[Canoe]

To start,
Each in turn (as in, not all disconnected at once), disconnect, clean, then reconnect all of the connections to/from the battery, alternator and solenoid. There can be visible hidden corrosion that robs voltage, current or messes with sensors (an eraser can remove the fine layer of corrosion from contact surfaces to make them nice & shiny clean). Also the disconnect, clean and reconnect for the car's body ground (likely a cable from the neg battery terminal out to the body aft of the solenoid, or even on the spring tower). And you may have a sensor or ground issue back at the gas tank (tank senders can be an issue with Eagles). I assume you cleaned the battery terminals and clamps to nice & shiny, then re-clamped the cables onto the terminals. I use dielectric grease on all connections to minimize future corrosion.
I assume the alternator pulley was the same, or you used the old one? Belt correctly tensioned?
Then see if the behaviour changes.

Soldering a wire is not recommended, as vibration can break the wire strands were they meet the solder, causing a later failure. An insulated crimp connector is more reliable - IF you use the correct size crimp and the proper crimp tool (not pliers, not vicegrips, etc.). Also for breaking under vibration, don't use solid conductor wire in vehicles; use stranded wire.

In future, there's also different alternators that fit in Eagles. The 94 amp one is popular. I have a reman of that.

My old notes:
AC-Delco 12SI clocked @ 3:00

94 Amp: AC Delco part #321-266, Lester(cross reference) #7294-3, BOSCH AL559N (N for new)
Application: 1984 CHEVROLET CAMARO 5.0L 305cid V8 4BBL (G ) with A/C, amperage 94,  regulator i/r,  clock pos 3,  pulley class 1979452,  voltage 12,  rotation cw
Any Lester # ending in 3 should have the same wiring connection position as the recommended one from the Camaro.

78 Amp: Lester #7278-3, will have the same wiring connection position.

[Senseirice]

I cleaned the terminals but I didn't replace them. I cleaned the connections too with some scotch pads while I had them apart. I didn't see any major corrosion but I figured I'd do it while I had it all apart. The ground goes from the negative terminal on the battery straight to to the motor so I'm assuming someone replaced it and I'll probably have to ground the negative to the body or find the motor to body ground and check that.