Just a quick guide on gauge cluster bulb replacement from a European point of view.
Getting the cluster out of the car is not that complicated and a corresponding picture thread available at NSX Prime.
Once pulled from the vehicle and investigated there seem to be five types of bulbs used. Four of them are wedge-base bulbs which are classified in this way.
- Diameter: 10 mm → T10
- Thickness of the base: 2.1 mm → W2.1 ('W' is for wedge)
- Width of the base: 9.5 mm → x9.5d ('d' is for dual - two wires)
- Result: T10 W2.1 x 9.5d (wattage and voltage are to be added)
The ffith bulb type is used to indicate the selected gear in AT models. It's T4.2, no wedge base but two long wires instead.
Large
Green Blue Black Gear Honda Part Number 37237-SA5-003 (lamp only)
37102-SA5-003 (incl. holder)37103-SL0-003 (incl. holder) 37102-S84-003 (incl. holder) 35505-SA5-003 (incl. holder) 78181-SF1-612 (incl. holder) Diameter 10 mm 6.5 mm 5 mm 5 mm 4.2 mm Wattage 3.4 W 3.0 W 2.0 W 1.4 W 1.0 W Classification T10 W2.1 x 9.5d T6.5 W2 x 5d T5 W2 x 4.6d T5 W2 x 4.6d T4.2
After roughly 100.000 km it's suggested to replace the illumination bulbs and potentially the gear indication bulb for 'D'. In my case the illumination bulbs were visibly darkened, the holder of the green ones (illumination, too) was darkened and started to become brittle. It's therefore advisable to replace the green ones with Honda ordered bulbs that include the lamp holder. The 'D' indicator was fine, though.
If you are planning on replacing all bulbs or servicing more than one cluster it might be interesting to get bulbs in larger quantities. The company BOSMA is selling all of above bulbs, even the ones for the gear indicator.
Minimum order is 10 pieces. I ordered one package of each - out of curiosity. They do fit perfectly and are working fine.
Large Green Blue Black Gear Voltage 12 V 12 V 12 V 12 V 12 V Wattage 3,0 W 3,0 W 2,0 W 1,2 W 1,0 W Classification T10 W2.1 x 9.5d W2 x 6.6d T6.5 T5 W2 x 4.6d T5 W2 x 4.6d T4.2 Order Number 5012363-BOSMA 501248-BOSMA-0002 501235-BOSMA-0002 50123512-BOSMA-0002 501273-0002
Even though this information looks simple and easy it was quite a task to identify each bulb. Some of the values in the repair manual are incorrect, some bulbs carry US-American numbers, are rated at 14 V instead of the European 12 V and the green holder bulbs are simply rare. Measuring of dimensions, sometimes even current through the bulb was necessary. Hopefully this write-up is helpful to someone having similar issues.