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Aftermarket gauge lights - wiring to dimmer switch


tinman_72

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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

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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/tech_library/EDiagrams/files/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.
 
Last edited:

tinman_72

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North Georgia
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1993
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Ford
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2.5 (4 Cylinder)
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2.5
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Manual
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2WD
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Factory
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None
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255/60R15
My credo
RoHS compliant
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

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