Editing Z31/lateanalogupgrade php (section)

==== The Process ====

* Remove the lower steering column plastic trim. Use a Phillips screwdriver for the 3 screws.
* Remove the trim around the steering wheel (plastic casing just behind the wheel). There are 4 screws, 2 per side. Take off the top portion.
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Remove switch pods on each side of the instrument cluster.
See:
[[Z31/Switchpodbulbs|Switchpod bulb replacement]]
* Drop the steering column by loosening the 2 golden bolts underneath (but don’t remove them). This helps you get the cluster out without removing the steering wheel.

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Remove the 2 Phillips screws from the instrument cluster bezel.

* Carefully remove the bezel from the instrument cluster area.
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Remove the 2 Phillips screws on the left and right of the cluster to free the unit.

* Slowly pull the cluster forward to access the rear.
* Press the top and bottom tabs on each connector to unplug from the cluster.
* Carefully sneak the cluster out between the steering wheel and dash.
* Now, we’ll upgrade to LED bulbs. Some modifications are needed.
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Remove the Gauge Face Lighting bar on top of the cluster (3 small Phillips screws on the bar, plus 2 auxiliary bulbs).

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Carefully remove the 3 PCBs (lighting bar and auxiliary bulbs).

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Remove the front gauge lighting bar to reveal the white lighting diffusers.

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About diffusers: Keep them for incandescent or LED bulbs. Remove only if using UV bulbs in the 365-390nm range (most LEDs are not true UV).

* Remove the acrylic plastic cover (4 screws front, 5 rear). Gently undo 4 rear and 2 front tabs.
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Carefully separate and lift the cover.

* LED Directionality: LEDs are directional, unlike incandescent bulbs, so add reflectors for better luminance.
* Red LED note: Red LEDs are focused and near infrared—consider reflectors or paint for better needle illumination.
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Mix premium white enamel paint well for reflectors (Testors Model Master recommended).

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Paint the underside of the front lighting bar flat white, as well as the PCB spots for temp/fuel bulbs.

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Paint the inside of the trough where bulbs rest; stir well and apply several coats. This boosts needle lighting with red LEDs.

* Review: Additional pictures of the cluster and bulbs.
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This cluster uses an acrylic diffuser for even illumination.

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The gauge faceplate is lexan, with two squares for temp/fuel gauges.

* The faceplate is orange lexan, screen printed and dotted with white paint on back for even light.
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Factory odometer/trip bulb: 2722 bulb, can be replaced with #74. Note acrylic diffuser.

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Center bulb/diffuser: can use #194 bulb.

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Bulb behind temp gauge: can use #194 bulb.

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Bulb behind fuel gauge: can use #194 bulb.

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Comparison: 11 Mini SMT LEDs vs factory #158 bulb. These are the tallest that fit.

* Z31 needles: poly with a weight. Painted fluorescent red for effect.
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Fluorescent red = orange/red, glows under blacklight. Blend with insignia red for deeper color.

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Result: Paint matches tachometer, looks more red.

* This method is great for stock, LED, or black light bulbs—needles look red day/night and glow under UV.
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Needles now glow red, even under black light.

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Red needles under black light.

* Reinstall needles, clean acrylic cover, button up screws.
* Test the cluster and gauges in car. If all works, tighten all remaining screws.
* View: With regular light and UV (no backlighting yet).
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Goal: Red needles achieved!

* Slide the cluster in, plug in illumination connector (behind tach). Turn on parking lights, check LED polarity (+/–). LEDs won’t work if reversed!
* Photos show: stock white needles, red colored needles, and finished cluster.
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Key point: All needles glow red; fuel/temp gauges have red effect.

* Optionally use UV light for fluorescent glow!
* Result: Cooler-running, longer-lasting LEDs, and red illumination for needles and gauges.