Re: wiring for gauges

[Brett Van Sprewenburg <brett@netacc.net>]

>Everyone who's installed aftermarket gauges:
>
>I'm trying to install a volt gauge and an oil pressure gauge. Here are my
>questions:
>
>1) The volt meter has two wires that obviously go to 12v positive and
>ground. Do I gain/lose accuracy depending on where I wire it in?

Yes, sorta.  The gauge will still be "right", but won't reflect the
maximum voltage available in your charging system.

>In other
>words, is there an advantage to running wires to the fuse panel (or even the
>battery itself) instead of just using the same leads as the light bulbs for
>the gauges?

Do not wire any gauge power (besides the lights) to the light circuit.
One of the main reasons is that the lights go through the light switch
dimmer.  Secondly is that this voltage source is probably not the one
you wish you sample with your gauge.  As I've mentioned a variety of
times in the past, there's a fuse box circuit designed for a stock
voltage gauge, it's just that most of our cars aren't so equipped. Look
for it on the Bentley diagram, find the wire behind the fuse box, and
tap it for the positive line of the voltage gauge.  No extra wires to
run, factory sampling position.  Simple as that.

>
>2) The oil pressure gauge has three wires. Logical deduction tells me that
>the "+" goes to 12v positive, the upside-down "T" goes to ground, and "G"
>goes to the sending unit. Unfortunately, this is my (failure-prone) logic,
>so I'd like to know for sure. Is this correct?

Sound right...the last set I hooked up had +, -, and S for sensor.

>Is there any reason (gauge
>accuracy, or whatever) not to use the same power leads as the light bulbs
>for the gauges, but to wire into the fuse panel?

Do not use the light circuit to power the gauges, same reasons as above.
I'd use the line you pulled for the volt meter. Adding a gauge will be a
small draw and won't throw off the voltage reading much at all.


>
>Thanks!
>Neal
>88 16v

==Brett

 \/  '84 Scirocco (ITB racer 2B) | "Hot VW's, take two home. They're small"
\/\/ '88 Scirocco 16v (Show), '85 Scirocco (Winter) | - brett@netacc.net

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