Autogauge Stepper Motor Series and Smoked Series Gauge Install and Review

From left to right: Oil temp, Oil pressure, Water temp.

The Oil temp gauge is an Autogauge Stepper Motor Series and the other two are Autogauge Smoked Series.

The Stepper Motor Series does the whole Defi start up ceremony where the needle does the full sweep and the lights flash upon start up. It also makes a loud, prolonged beep noise upon start up which can be a bit annoying. The Smoked Series are silent on start up.

Prior to fitting

The Stepper Motor Series oil temp gauge has a small white (2mm or 2.5mm allen) calibration screw at the back of the gauge. So before I installed the gauge to the car I checked the calibration by hooking it up to a spare car battery I have and placing the sensor in a pot of water. I boiled the water and adjusted the screw so that the gauge would read 100 degrees Celsius to ensure accuracy.

The Smoked Series do not have calibration screws, at least not exposed in its case - I have not opened them up to inspect internally.

The Install

First, I checked the combined current draw of all three gauges with a multimeter and found that it is around 0.3 - 0.4 amps. This was surprising as I was worried I'd have to split the wiring for the three gauges to spread the current draw to prevent exceeding the amperage rating of the 180sx's interior electrical circuits (eg cig lighter, audio unit, etc). I can't guarantee that this is the case for all after market gauges so check the current draw of your particular gauge!

With this knowledge, I tapped into the wires of the audio unit power supply: Permanent 12V (battery+ive), Accessory, and Illumination. And earthed it to the body. 

Automotive 8Pin connectors are your friend here:

Illustration from the Narva Website

What you have is three gauges, meaning three earth wires, three +ive, three sender wires etc etc.

You need to combine each category into one pin. Each pin of the Narva connector is rated at 20amps so its more than enough to handle the current draw of these gauges.

Note: the stepper motor series has a permanent 12V+ wire for peak recall memory so you'll need add that, if you are just installing the smoked series then the above diagram can be followed 100%.

This is the neatest way to install these gauges. Hard wiring them by soldering the wires into your existing electrical circuits means you need to cut the gauge out if you wanted replace them or remove them for whatever reason. Using connectors means you can replace each gauge (if one of them fucks out) efficiently and neatly - just like factory.

Senders

Im running a JAB design coolant neck sandwich plate (which is exactly the same as the Gktech coolant neck sandwich plate [I believe is a "JAB" design originally]) for the water temp sender and a Shadow Pro oil filter sandwich plate for the oil temp and pressure senders. Best thing for pressure senders is to isolate them from vibration - that means installing it OFF the engine (ie on the body somewhere) and use a braided oil line coming off the sandwich plate and onto the sender. This will prolong the life of your sender unit. 

Use thread sealant (I used Permatex thread sealant and it seems to work quite well) for all the sender threads.

Sandwich plate between head and coolant neck. (Easier to view if you download the image and zoom in)

Pressure sender mounted remotely. I still need to get a braided line 1/8NPT male and female fittings.

Completed Install: