From: Dave Darling [darling@simlab.arc.nasa.gov] Sent: Tuesday, May 18, 1999 8:00 AM To: Lawrence@rennlist.com Cc: 914 Digest (E-mail) Subject: Re: Electrical problem in my 74 2.0. At 7:37 PM -0700 5/17/99, Lawrence wrote: >Occasionally, still having alternator light come on when the headlights >are on. > Voltage gauge (in console) indicates a drop of about a volt. Turn signals >seem to cause a voltage drop when they flash. It drops about one more >volt, in >tune with the flashing. Foglamps appear to be stock, and dont cause >voltage to >drop. Headlamps appear to be stock. > >Very strange thing: the 4-way hazard lamps DON'T cause any voltage drop, >like >the turn signals do. Neither do the brake lights or reverse lamps. The voltage gauge in the console is really just there for amusement. It does not indicate the health of the charging system, except in a very rough and indirect fashion. I'm gonna rig mine up on a relay and get rid of all of those fluctuations, eventually. If you check the wiring diagram (Haynes or the color ones on the Pelican site) you'll find that the voltmeter works off of a circuit coming out of the ignition switch. This circuit also powers a number of other things, like the brake lights, turn signals, etc. Using those things will change the voltage in that circuit, especially if there is any dirt in any connections along the way. (The relay board and ignition switch spring to mind.) BTW, the alternator light "compares" that circuit to the "D+" circuit from the alternator. A voltage difference between the two will cause the light to come on. Headlight and turn signal drop of about a volt on the gauge is common. Mine does that, and also drops about a volt for the brake lights. Foglights have essentially no effect on the gauge in my car. >Replaced both non-functioning license plate bulbs - I'm not sure the license >plate bulb assemblies are stock. I suspect they are from a 912. The >bulbs at >the FLAPS were too large to fit into the holes. Oh, they still dont work. Check that you have a reasonable ground at the assembly. Then turn on the parking lights, and check for +12V at the assembly. (BTW, the stock bulbs are rather small. The parts diagrams on Pelican should also show the stock light assembly, which screws upward into the bottom of the bumper cap.) If you don't have +12V, then check for voltage at the rear trunk's light. That is also on any time the headlights or parking lights are on; the wire goes from there back to the license plate lights. I'm not sure where exactly it goes from there. You'll have to check the wiring diagram yourself. --DD Dave Darling 74 914 2.0 (decapitated) darling@simlab.arc.nasa.gov "OFF WITH ITS HEADS!"