Aftermarket gauge lights - wiring to dimmer switch

[tinman_72]

Hello,

I have a 2wd '93 Ranger 5 speed four banger that I am adding an OEM tachometer to. I have already installed oil pressure and water temp gauges on the pillar but I never got around to hooking the lights up on them. I thought that since I have the gauge cluster out, now would be the perfect time to wire them in.
Normally when I add electrical accessories I run a new hot wire and wire in a relay to be switched on/off by existing accessories. However, I am thinking it would be nice to have these gauges hooked into the factory dimmer switch. Can I just splice into the factory gauge lighting and run directly off of them or would it add too much to the circuit?

Thanks, Derek

 

[RonD]

You should be OK to add them to existing circuit, in this wiring diagram it shows the backlighting to be running thru a 10amp fuse:
http://www.therangerstation.com/tec...iles/Diagram_Instrumentpanellights_1990on.JPG

Which means the dimmer and wiring can handle up to 10amps.

Instrument panel bulbs are at most 5 watts, usually lower, below 3watts.
5watts at 12volts = .41amps (Watts divided by Volts = Amps)
So 10 5 watt bulbs would be 4.1amps
20 5 watt bulbs 8.2amps

If you pull out one of the instrument panel bulbs and get the part number you can find it's exact wattage to do a precise calculation.

 

[tinman_72]

Wow, thanks Ron. I wasn't expecting a real answer based on physics and math.

It looks like they are 194 bulbs so they are 3.78 watts. I just got done hooking them up and they work fantastically!

 

[RonD]

Good work