by spencerforhire » Fri Sep 20, 2013 5:53 am
Clyde is correct; the temp and oil senders provide a ground to light the bulbs, and the alternator works a little different but has the same outcome. The alternator is actually turned on by the voltage on the wire coming through the filament of the bulb. Blown or missing bulb= no charge. With key on, engine not running, the bulb lights because it sees ground from the regulator. When the alternator is charging, there's 12 volts on both sides of the bulb so it turns off.
The "fleet"-
72 Vega HB Drag Car -383/'Glide/9"(9.35@146.19)(5.94@117.28 1/8th)
77 Vega Estate wagon- project(someday)will have TPI305/T-5, S-10 spindles/axles
76 Vega GT- 400/4spd/9" retired from active duty(rusty)
06 Silverado 2WD ex.cab daily
03 Silverado 2WD ex.cab (retired)
06 Haulin' 20ft enclosed car transporter
06 GMC Canyon Shop truck
07 Colorado project( 5.3 4L60e swap)
99 Saturn SL1- wife's car
01 Saturn SC2- son's project
07 Saturn Ion Redline project
and 4 more Saturn "parts cars"
Note- the very act of listing all of these has made me realize I have some kind of problem.....
Visit http://www.spencerforhire.ca