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On 12 Nov 2003 at 8:19, Daniel Baum wrote: > Perhaps we're looking at it the wrong way; maybe originally the red light in > the switch was supposed to be the only interior indication that the > emergency flashers were working, but they couldn't stop the dashlights > flashing when the ignition was ON, because they needed this for the > indicators and it's all based around the same circuit. So later they kludged > it a bit more so that the dashlights flashed whether the ignition was on or > off! All the dash indicator lights generally have 12V applied to one side of them when you turn the key ON, and then they light whenever there is a good ground provided on the other side. I think that the 68-70 flasher just provides an intermittent ground for those lamps. So when you turn the ignition OFF there is no longer any 12V supplied to those bulbs and the intermittent ground is still provided, but it doesn't do anything. In the later system, the relay provides an intermittent 12V (rather than an intermittent ground) to both the dash lights and the external bulbs, all wired in parallel, so, with the ignition on, when that flasher 12V is on, the dash lights are off (they're getting 12V from both sides) and when the flasher 12V is off, the dash lights are on (because the flasher side is grounded back thru the external filaments. Thus, on the late systems (71-3) I think you will find that the phase of the dash bulbs changes when you turn the key ON. Another thing I think you'll find on the late systems, but I've never tried it, is that the dash lights won't flash with the key ON if you remove all the external bulbs, since those provide the ground path for the internal bulbs -- Jim Adney jadney@vwtype3.org Madison, WI 53711-3054 USA ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ List info at http://www.vwtype3.org/list | mailto:gregm@vwtype3.org