Wiring up pins and gauges

[Aaronbrook37]

Hey all - would love some help wiring up a quick release wiring harness for my new gauges to ensure I have decent anti-theft until I bother putting an alarm in. I sourced these parts from a Chinese Ebayer named uustore2011 who has some pretty spiffy stuff, all of which I scored for a grand total of $56.12. Here's what the assembly looks like buttoned up quickly out of the box - boost/vac, voltmeter, and oil pressure:



I'm planning to pop a hole in the back of this unit and use trailer connectors and a barbed fitting for the vacuum line all wrapped up in some wiring loom to keep things pretty and clean. The vacuum line I can handle with a golf tee plug, and trailer plugs are a dime a dozen at the local auto parts stores in a range of gauges and sizes. What makes this process a little bit complicated is that I must account for illumination, illumination grounds, ignition, ground, and sensor wires along with the vacuum hose for the mechanical boost gauge. All of the fittings and wires are designed for 18AWG.

1) The six wires shown are illumination and illumination grounds - can I just merge them into a larger gauge 2-pin connector instead of running six smaller wires through the gauge pod? That'll simplify hooking it up to the dimmer switch or dash lighting harness as well. Something like this perhaps: http://www.picocanada.com/en/product/1878.php.

2) The remaining six pins live on the non-mechanical voltmeter and oil pressure meter. Four are for ignition switch power and grounds, and the last two are the actual signal wires. http://www.picocanada.com/en/product/1879.php.

3) Any reason why a double-ended barbed fitting would be a bad idea for the vacuum line feed's quick disconnect? I don't foresee it being a vacuum leak or anything.

4) Sort of a dumb question, but can someone explain to me the difference between the sensor and ignition switch wires on the voltmeter? I would infer the volt sensor must be always hot and the ignition switch must be self-explanatory.

On the dash side of things, I'll just drill a hole for some wiring loom through the clock delete panel I suppose.

Thanks all,

A

[Icedawg]

1) The six wires shown are illumination and illumination grounds - can I just merge them into a larger gauge 2-pin connector instead of running six smaller wires through the gauge pod? That'll simplify hooking it up to the dimmer switch or dash lighting harness as well. Something like this perhaps: http://www.picocanada.com/en/product/1878.php.

2) The remaining six pins live on the non-mechanical voltmeter and oil pressure meter. Four are for ignition switch power and grounds, and the last two are the actual signal wires. http://www.picocanada.com/en/product/1879.php.

3) Any reason why a double-ended barbed fitting would be a bad idea for the vacuum line feed's quick disconnect? I don't foresee it being a vacuum leak or anything.

4) Sort of a dumb question, but can someone explain to me the difference between the sensor and ignition switch wires on the voltmeter? I would infer the volt sensor must be always hot and the ignition switch must be self-explanatory.

1) Yes you can merge all those power lines lines, and them merge the grounds to each other too, since you want them all to turn on at once anyhow.
2) You can merge the ignition switch lines to each other, and merge the grounds to each other, to get two lines in total. Obviously signal lines must be kept separate. In fact, if you want illumination on all the time, you can merge the illumination lines with the ignition lines. In any case you can merge the grounds for both ignition and illumination to cut ground down to a single line.
3) I can't picture what this would look like. If you think it won't leak, then sure.
4) I think your inference is right, but if you don't have the ignition on you won't see the readout anyhow, so you should be able to merge these two lines and run it off the ignition line alone. It there is more current draw on the ignition line than the sensor line it will read a touch lower, but probably not enough for the meter to show a difference you care about anyhow.

[Aaronbrook37]

Cool! Thanks bud. How does this look? Did I get this right?

[Aaronbrook37]

Just got everything wired up with some test alligator clips and two 9V batteries. Oil pressure maxed out without the sensor being there and the voltmeter went to 9V obviously. Illumination looks pretty good though the boost gauge isn't as blue as the other two - something I kind of like! Now to get it loomed up, plugged in, and then installed! Will pick up a couple of trailer wire plugs tomorrow at the parts store and go from there.

[Aaronbrook37]

Last step is just tightening up the terminal nuts a little more securely and making an exit point on the back of the cluster for the loom to run through!

[Aaronbrook37]

I have reason to believe that my boost/vacuum gauge is a bit faulty. On my larger vacuum gauge, this motor runs the steadiest 22 inches of vacuum I have ever seen. Makes sense with the overhauled head, lapped valves, and fresh headgasket I suppose. I have a single section of 1/4" vacuum line running directly from the intake manifold into the cabin and to the backside of the second mechanical gauge. There are no pinches, kinks, or cracks in the line. However, it insists on reading 25-30 inHg no matter what I do. Any thoughts? Perhaps the gauge is leaking internally and needs some teflon tape somewhere?

[nitrofarm]

I have reason to believe that my boost/vacuum gauge is a bit faulty. On my larger vacuum gauge, this motor runs the steadiest 22 inches of vacuum I have ever seen. Makes sense with the overhauled head, lapped valves, and fresh headgasket I suppose. I have a single section of 1/4" vacuum line running directly from the intake manifold into the cabin and to the backside of the second mechanical gauge. There are no pinches, kinks, or cracks in the line. However, it insists on reading 25-30 inHg no matter what I do. Any thoughts? Perhaps the gauge is leaking internally and needs some teflon tape somewhere?

If the new gauge had a leak that needed sealing it would read LESS vacuum right? Like 18 compared to the 22 that the larger one has read in the past.

[Aaronbrook37]

If the new gauge had a leak that needed sealing it would read LESS vacuum right? Like 18 compared to the 22 that the larger one has read in the past.

True... but I've noticed that pinching the feed hose tends to lead to high readings, so it could go either way I suppose. Hopefully it's accurate enough for dyno testing though! I've got them jerry-rigged in there for the moment. May do a more permanent setup through the clock delete panel when I feel up to tracking down those tiny wires.