Datsun 240z Custom 6th Gauge Install

This is a 3D printed (PLA plastic) gauge pod for a 1969-1973 Datsun 240z (S30 chassis). This allows the installation of a 6th gauge located in the center console on top of the existing fuse panel cover/seatbelt light tray. The use of this gauge pod allows the addition of an extra gauge (oil temperature, voltage, trans temp, intake temp, EGR temp, diff temp, cylinder head temp, boost gauge, fluid level, clock, tachometer, speedometer, O2 sensor, vacuum).

The use of this gauge pot renders the rear window defroster switch inoperable unless it is rerouted to a different location, along with the lights for the seatbelt and the choke. Many current 240z owners do not use these lights, and if you prefer, an LED can be rerouted to an alternate location for these lights.

I have filmed a series on doing the entire dashboard with these same gauges, watching these may help with the wiring:

240z Dash Restomod (YouTube)

• 1969-1973 Datsun 240z
• 3D printer or access to 3D printer for the Gauge Pod (.stl file)
• 2-5/8" gauge (preferably from SpeedHut (tested and fitted))
• two sided tape
• Multimeter
• philip-head screw driver
• adjustable wrench
• wire strippers
• solder gun and solder
• heat shrink
• various wire connectors, terminal connectors, wire splicers
• bondo and paint
• zip ties
• plastic resin glue
• (2x) in-line fuse (comes with the SpeedHut gauge kit)

I used a Tronxy X1 printer with black PLA filament. The bed side is 150mmx150mm minimum for this print. The photo attached shows my CURA settings, a 0.15mm layer height resulted in the best print, as I went through multiple test prints and redesigns before this. It took about 16 hours for the print to complete. Be sure to use supports set at a 45 degree angle minimum for structure.

Periodically check your print to be sure it is coming out correctly.

You definitely may use ABS filament to print this instead and eliminate one of the following steps of sanding/bondo/priming/painting with the use of acetone to smooth the print instead.

Remove all of the support structure from the print and test the fitment of the gauge pod onto the fuse panel cover, it should fit perfectly without any wiggle.

Then test fit your gauge in the gauge pod, it slides in from behind with the existing trim ring on the front face.

If the fitment is not exact, be sure your print settings were correct, you may also slightly modify fitment in the following step using bondo.

Using a heavy grit (80-100) sandpaper, handsand the gauge pod to smooth the ridges, then move onto a lighter grit (150-250). Once it is smooth, apply a thin coat of automotive bondo to fill the darker, deeper areas. Once this is dry, sand smooth using a lighter grit (250-350) sandpaper. Use automotive primer to begin the painting. Once primer is dry ( you may use filler primer for a even better result and sand this), apply 2-3 separate light coats of your choice in color of spray paint.

Using plastic resin glue, apply a thin amount around the trim ring of the gauge (near measurement C in the photo), and the inside of the gauge pod where the gauge fits into. Make sure the gauge is centered and use painters tape to hold it in place until it dries for at least 24 hours.

Remove the fuse panel cover and remove the rear defrost switch, choke light, and seatbelt light from the cover using a philips-head screw driver. This will allow an area for the gauge wires to pass through. Be sure to mark the wires going to the rear window defrost switch if you wish to reroute these to an alternate switch. Pull the gauge wires through the seatbelt light hole and split & strip the wires (red/white/black) for soldering.

• Shown in the photo are 3 groups of wires. The large black wire on the top left is the sensor wire, the red/white/black is the power supply for the gauge. The black wire on the top right with the 3.5mm jack is the gauge setting button, this plugs into the back of the gauge to configure the data ranges and high/low warning light.

1. GAUGE POWER AND GROUND

• Start with the group of red/black/white wires. The red is gauge power supply, the white is the needle light power supply, and the black is ground. The red and white wire can be spliced together if you prefer that your needle light comes on when the gauge turns on (this is the most common method). You may go about connecting these wires whichever way you prefer (solder, butt connectors, male-female connectors). Once they are together and matching, you can use the now-extended wires to connect to ignition power and ground.
• Connect your in-line fuse (no greater than 3 amp) to the red and white wire in your preferred method (solder and heat shrink is preferable)
• Use your multimeter to test the fuse panel for power on each fuse with the key out of ignition, find which fuses have power and mark them. Now, turn the key to ACC (engine not running, ignition power not on) and test the remaining unmarked fuses for power, and mark the ones with power. Finally, turn the key to the ON position (engine not running) and test the remaining unmarked fuses to verify that they NOW have power. Based on the fuse panel, the fuse you should be looking for is the middle left fuse marked IGN. This will be your power supply for your gauge.

• DISCONNECT YOUR NEGATIVE TERMINAL FROM YOUR CAR BATTERY

• Remove your fuse panel and flip it over, solder or splice a connection onto the wire or tab of that fuse from behind to your in-line fuse of the red and white wires.
• For your black (ground) use a terminal connector or o-ring style connector attached to the end of the black wire and connect it to screw behind the fuse panel that screws into the body.
• You should now have the red/white/black wires coming from the gauge connected to the fuse panel and the body, through the fuse panel cover.

2. GAUGE DASH LIGHTING

• Begin with connecting the supplied inverted to power and ground. This is similar to the previous steps, however you can choose to supply the inverter power with ACC power instead of IGN power. This is the two fuses on the top left of the panel. This will result in the gauge backlighting turning on with the rest of the dashboard when the key is turned to the ACC position. You can place the ground on the other screw behind the fuse panel. Be sure to use an in-line fuse for the power side of this circuit as well.
• Once the inverted is connected to the fuse panel power and ground, connect the matching connections to the gauge through the fuse panel cover (black, black&white striped wires)
• Use zipties to bundle the wires and tuck under the center console out of the way.

This step is specific to an oil temperature sensor. However, I will supply general instructions for whichever sensor you have.

For a voltmeter or ammeter sensor, you do not have a "sensor" wire, it receives its data from it's power supply.

For any temperature, level, or pressure sensor, it must be installed into the respective system and the wire ran to it. Some may be more difficult than others.

Feed Sensor Wire to Engine Bay and install sensor

• Connect the sensor wire to the gauge and route the sensor plug through the dash, through the firewall grommet, and into the engine bay similar to my photos.
• Install your sensor in either the existing oil pressure sensor threaded hole, or drill and tap a hole on the oil pan. (drilling and tapping requires you to drain your oil, remove the oil pan, drill a large hole for a threaded nut or bung to be welded on to the oil pan)
• Thread the sensor into the hole with nylon tape to ensure it will not leak, then connect the sensor wire to the sensor.
• Use zip ties to hold sensors wires along the body, with the existing wiring loom, to keep away from hot or moving parts.

Be sure all of your connections are insulated correctly, not crossing, and firmly connected.

Plug your negative battery terminal back onto your battery, with your key OUT of the ignition.

Turn your key to ACC, does your gauge backlight turn on? (be sure the adjusting dial for the light is turned all the way up!)

Turn your key to IGN or ON, does your gauge needle turn on and fully cycle?

If any of these do not happen, check your wiring and fuses and verify power and ground with your multimeter.

Using the supplied 3.5mm jack wire with button, plug this into the back of your gauge while key is out of ignition.

Follow the instructions supplied with the gauge for configuring your data ranges and high/low warnings.

Once you finish configuration, you may either remove this button wire, or bundle it behind the fuse panel cover if you plan to reconfigure your gauge in the future.

Use your double-sided tape on the raised section of the fuse panel cover, around the edges, to hold the gauge pod in place when you put it together.

Triple check everything, and return the fuse panel to its original location.

Put it all in place and enjoy your new data!