[Vwdiesel] glow plug indicators

Sandy Cameron scameron at compmore.net
Tue Dec 21 16:38:34 EST 2004

I already have individual wires going from a common point above the injector
lines, to each plug.

I did not bother with an indicator system at the time, as I can open up the
common point in a minute and test each plug separately with full power
(through an ammeter).

Next one I do, I will make all 4 independent leads (#12 wire) the same
length and bring up a pair of soldered-on light guage leads from each. (old
broacast and phone co. techs do everything on pairs isolated from ground).

I will bare the #12 wires just short of the ring terminals, and solder a
metering wire to each end.

The current through the individual #12 wire will cause a small voltage drop,
which can be read with a low voltage voltmeter, or a milliammeter.

Any wire used as a shunt should be continuous, no joints or terminals to add
unstable extra resistance to the shunt. I would only put a 12v bulb across
the fuse to indicate it has blown. It would be unwise to use it as a
metering shunt, as if it blows, your milliammeter will smoke too.

I doubt if there will be enough drop over 10" of #12 to light a led, but I/C
board fanatics could likely  come up with a set of op-amps to do it from the
millivolt sample. I will just use a milliammeter and a 4 position switch


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