Weird Electrical Happenings-Part 1, ...turning headlight knob effects full gauge Options

[7TPorsh]

I have a bunch of little weird electrical things going on...so i'll attack one at a time:

The fuel gauge (stock combo gauge) moves as follows under different conditions:

- Ignition off/headlights on- turning headlight knob up makes fuel gauge go from empty to full; turning down go back to empty.

- Ignition on/headlights on- fuel gauge show reading...turning knob up increases the reading on the fuel gauge by 1/4 tank; turning down decreases...so 1/4 fluctuation in the fuel gauge depending on how the headlight knob is turned.

Tend to think the full bright on the headlights translates to a closer fuel reading. But why? is the power source for the fuel gauge incorrect?

I checked the schematic, but it looks like a Lucas engineer designed the wiring for the combo gauge.

[7TPorsh]

Well i checked around...behind the front trunk pull above the fuse box was a bundle of brown wires (about 11) are twisted together. They weren't even grounded. Sheeesh!

So I put clips on them and grounded them to the frame behind the speaker cover.

Now the tach, oil pressure light and gen light work. Yahoo.

But... the gen light goes on now with the parking lights...not the headlights. Did I miss a ground or did i ground something I shouldn't have. The voltmeter goes down a volt or two when this happens.

Also Part Two problem isn't fixed with this.

[realred914]

Well i checked around...behind the front trunk pull above the fuse box was a bundle of brown wires (about 11) are twisted together. They weren't even grounded. Sheeesh!

So I put clips on them and grounded them to the frame behind the speaker cover.

Now the tach, oil pressure light and gen light work. Yahoo.

But... the gen light goes on now with the parking lights...not the headlights. Did I miss a ground or did i ground something I shouldn't have. The voltmeter goes down a volt or two when this happens.

Also Part Two problem isn't fixed with this.

the alternator light should have a postive power on one lead all the time the ignition is on, the other end of the bulb goes to the engien bay toward the laternator. when teh alternator is working it puts + 12 on this wire, which is the same as on the other wire to the buld, so there is no light (both wires to bulb now have +12 volts on them) if the alternator is not putting out +12, then the light still sees +12 on the one sid, but less than +12 on the other side, the difference between the two wires in volts is what will make the lamp glow. the lamp may nto glow if the waire have a msall voltage difference (say +12 and +11 volts so the differeance is only 1 Volt, no glow, but if the alternator starts to die and is only putting out +2 volt then teh lamps "sees' a difference of 10 votls (12-2=10) and it will glow then.
Note none of the two alternator light wires connect to ground!

so one of the two wires is some how hooked up to the parking circuit

Some clue would be helpfull,....

1.... does this do this when teh ignition is on or off or both?

2. does this do this when the engine is reved (supposedly the alternator is putting out a look of volts when reved)?

3. Does the alternator light appear to work normally otherwise if the parking lights are not used (ie glows with ignition on, but no engine running, and goes out after engine is started and reved?)


find out th e three clues above and post, we can work from there.