Lots of questions about aftermarket gauges.

[Mike1357]

I've been looking into a set of aftermarket gauges for quite some time now for the purpose of keeping a better eye on the vitals of my car. I have read through a lot of threads on here concerning gauges and the various different methods of installing and running them.

I start this thread hoping to answer any questions that I or anyone else has concerning anything about gauges. Eventually I want to create a detailed DIY when I do go to install my own set of gauges, so I want to know everything I can to make an informed DIY.

I'll start off with the three gauges that I plan on installing and the three that I have seen together most often in cars that aren't boosted.

OIL PRESSURE GAUGES:
The easiest method I've seen of installing one of these is with a sandwich adapter between the block and the oil filter. I know teflon tape is a must when installing one of these and that you have to lube the seals before putting it all back together. Any other tips?
QUESTIONS:
*Which hole in the firewall would be the best to use for running the sensor wires back into the cabin? The hole by the ECU.

WATER TEMPERATURE GAUGES:
I have read about 3 different ways to install these.
1) a water hose adapter.

2) tapping a block drain plug.

3) a T fitting allowing the use of both the stock and aftermarket sensors in the stock sensor hole.
(could not find a picture)
QUESTIONS:
*When using a water hose adapter, which hose would be the proper one to have the adapter on? The top radiator hose.
*If you tap the drain plug, would the fitting get in the way of an oil sandwich adapter? Will the temperatures there be within what the gauge can read?
*What does this T fitting look like and where would it be (I'm a picture person; I learn visually)?
*Which method would/do you use?
*Which hole in the firewall would be the best to use for running the sensor wires back into the cabin? The hole by the ECU.

VOLTAGE GAUGES:
I know this one might seem easy, but I've heard a couple of different mounting points from the battery itself to the alternator.
QUESTIONS:
*Where would be the best place to run the gauge to receive the most accurate voltage readings? At the battery.

GAUGE POWER:
For powering the gauge itself and controlling the lighting of the face. I already know that you want to find a power source that is live when the key is turned to the accessory/running notch. From what Ive read a good place to get power is from fuse panel inside the car by the dead pedal like so:

I've also read that its a good idea to fuse the power lines.
QUESTIONS:
*Where is the best place to get power for the gauges? From the battery using a relay.
*Can you run 3 gauges from this one power source or would you need to get separate power sources for each one? If separate power for each is needed, where?
*When adding a fuse, what's the best method to add one? What rating should the fuse be? Can you use one fuse for the 3 or do they each need a separate fuse?
*For the gauge lighting, where should you wire the signal wire so that when the parking lights/dash lights are on, the gauges will be lit? Can all 3 be run from this one place? The radio illumination wire will work.


This pretty much covers what I want to know for now. Whenever a question is added or answered, I'll update the first post. Thanks in advance to all contributors for your help.

[sonikaccord]

OIL PRESSURE GAUGES:
The easiest method I've seen of installing one of these is with a sandwich adapter between the block and the oil filter. I know teflon tape is a must when installing one of these and that you have to lube the seals before putting it all back together. Any other tips?
QUESTIONS:
*Which hole in the firewall would be the best to use for running the sensor wires back into the cabin?
The one above the ECU

WATER TEMPERATURE GAUGES:
I have read about 3 different ways to install these.
QUESTIONS:
*When using a water hose adapter, which hose would be the proper one to have the adapter on? I assume the top radiator hose?
I believe the top. That's the hot side of the pump. Well to make it simple, find the thermostat and put it into the same line.
*If you tap the drain plug, would the fitting get in the way of an oil sandwich adapter? Will the temperatures there be within what the gauge can read?
IDK what a sandwich adapter is nor if what temp the coolant is at the drain.
*What does this T fitting look like and where would it be (I'm a picture person; I learn visually)? Any disadvantages?
Like this...kind of
*Which method would/do you use?
Water hose adapter. Easy and less chance of something going wrong. You can also go back to stock.
*Which hole in the firewall would be the best to use for running the sensor wires back into the cabin?
Hole above the ecu
VOLTAGE GAUGES:
I know this one might seem easy, but I've heard a couple of different mounting points from the battery itself to the alternator.
QUESTIONS:
*Where would be the best place to run the gauge to receive the most accurate voltage readings?
The battery. The voltage is filtered at the battery and will give you a better reading.
GAUGE POWER:
QUESTIONS:
*Where is the best place to get power for the gauges?
From the battery using a relay. Connect it so that it switches with your accessories.
85-ACC
86-ground
30-12v battery
87-gauges
I believe it's a factory ground by the fuse panel
*Can you run 3 gauges from this one power source or would you need to get separate power sources for each one? If separate power for each is needed, where?
You can use the same source and daisy chain them to each other
*When adding a fuse, what's the best method to add one? What rating should the fuse be? Can you use one fuse for the 3 or do they each need a separate fuse?
One fuse. I don't know how much current the gauges draw but I'm sure it's not that much. 10A or 15A at least 12" from the battery.
*For the gauge lighting, where should you wire the signal wire so that when the parking lights/dash lights are on, the gauges will be lit? Can all 3 be run from this one place?
The illumination wire in the radio harness. All three can be run from this wire.


This pretty much covers what I want to know for now. Whenever a question is added or answered, I'll update the first post. Thanks in advance to all contributors for your help.

Answers in blue .
I know you may need some more clarification though.

[cb7rush]

as for wiring as long as you use an inline fuse and have about a 10gauge wire going to three different 14 gauge wires youll be fine..the main wire needs to be about 10 gauge id say..

[Mike1357]

* Take about 2 feet of 10 gauge wire and throw a fuse on there within a foot of the battery.
* Use this for power via a relay connected to the battery and a switched source and somehow get the three gauge power wires and the voltage gauge wire onto this one wire attached to the same relay (not sure how to go about doing that).
* Ground all of them at the universal ground by the fuse box.
* For the gauge signal wires, do another 10 gauge setup to a switched source (radio illumination wire) so that all 3 receive their signal from the same place (fuse this too?).
* What color is the radio illumination wire?
* Run all of the wires into the cabin via the firewall hole by the ECU.

This would be an oil sandwich adapter for the oil pressure:


I'm planning on using Glowshift 7 color gauges in the din slot under the radio. I believe I'm going to do a T fitting at the top water neck in order to keep the stock sensor there and get accurate readings with the aftermarket sensor as well.