disconnected alt light

[fusername]

so pretend, hypothetically, that I left my alt charging light disconnected for say a year (3k miles). If I suddenly remembered about it and hooked it back up, is the lack of charging due to a dead alt? The car gets driven in bursts, so I often charged the battery, so I never noticed the alt wasn't working due to lack of light (right, thats how they work?) I made a quick kludge wiring for the light, and it would not light up proper, and in a quick test I did not see charging voltage on the battery. Is it time to dig thru my alt pile and try and find a new one, or will hooking it up right and waiting for magic fix it?

[Dale M.]

Think so....

If you ground lead at alternator (d+) alt light (kludge or not) should light when ignition goes on....

IF yes, change alternator (or regulator).... If no, chase alt lamp wiring...

Dale

[fusername]

shouldn't it light if you connect the alt light to 12v, key on? the alt line goes high when the alt is working, is my understanding of the system.

[Dale M.]

One side of ALT lamp is always connect to 12 volts (at speedometer in stock bug wiring).... Alternator theory is when alt IS NOT spinning up (not generating) a GROUND is put out by alt regulator circuit on D+ terminal, and causes lamp to light.... As alternator spins up a shot of 12 volts comes through lamp to initialize alternator (start charge process) as charge process builds the ground on the D+ wire transitions to 12 volts, as D+ lead transitions to 12 volts it causes ALT lamp to be powered by 12 volts from both ends of lamp circuit.. As this happens, there is less current low through lamp and lamp dims, as the voltage becomes equal on both sides of lamp it goes out because no current flow (12 volts to 12 volts is a no current flow condition)....

Dale