Thank you Dave, Steve, and Randy! Wow, three responses within two hours. Can't beat that.
Just got back from two hours of drooling on my car... because I had to hold the flashlight in my mouth while fighting with the battery ground wires!
Found three wires that went off the battery. Large copper braided one went to a lug on the transmission, had a second extra grounding lug on it midway along that wasn't used. Couldnt' find any lug on the frame to attach it to. Small insulated one went (as far as I could see) to the engine mount arm. Large insulated one dissapeared from sight under the air filter. Cleaned all the contacts I could reach and snugged the battery back in. Sound ok, dave?
I think the alternator field winding wire is connected okay. Here is a more detailed diagnostic.
Battery gauge in the cockpit works, verified with a multimeter. When the car is just started the battery gauge reads a happy 12 V until I rev it past
3000 at which point the battery light on the dash clicks off and the meter goes up to 14V, staying there as I go back to idle. Sounds good so far.
Shifting the (manual) transmission into any gear with the lights still off only makes the battery gauge jiggle, down maybe 1/4V at most.
If I pull out the lights knob half way (running lights only, no headlights), the main instrument panel and the auxiliary gauges light up OK and the voltmeter continues to read 14V. If I then shift into reverse, all the auxiliary gauges' lights die, the voltmeter drops to rock bottom, but the main instrument panel is unaffected. Taking it back to neutral brings the auxiliary gauge lights back on and the voltage back up to 14. Couldn't verify the reading on the battery leads as I didn't have a friend around to keep the clutch in with the tranny in gear while I ran around under the hood.
Randolph, there wasn't a remote start system ever installed that I know about, however there was a car alarm installed at one point, the brain and horn are still present though all the (visible) wires have been cut. Doubt it would want to know about the car being in gear, however they might have hooked it up to the ignition? Doesn't seem too suspect.
Steve, I dug around under the car as best I could but I wasn't sure where to look for "On top to the transaxle in front of the speedo cable" for my
6-position shift sensor switch. I'll get to know the navigational names once I have a manual. There is a little light on the floor of the instrument cluster dead center that might be the upshift light Randolph mentioned. I will try and investigate the 6-position shifter switch further, that sounds like the likely culprit.
It sure is hard to think without a wiring diagram in front of me. Would the six position shifter indicating switch be shorting to ground? Why only affecting the three auxiliary gauges and not the main instrument panel? And not blowing any fuses that I can see?
What a joy, eh? Thanks again for the help, let me know if any more ideas come to mind!
Cheers,
-Antony