Dash Dimmer Switch Fix W20D W22D Serrano & Others

[PatricksPC]

This from an old post (not Mine)

Quote:

Originally Posted by FreshAir First let me tell you how my dimmer switch is wired. Top to bottom. Back of switch. -------Brown wire -------Black wire -------White wire -------Green wire The Tech spliced into the Green wire with a pressure snap wire connector where it came out of the dimmer switch connector, ran a wire down to the fuse box cover and to a 10 ohm 50 W heat sync resistor. From the resistor he ran a wire to the ground screw on the fire wall behind the brake pedal.

Pat,
This make a lot of sense. I took my Serrano in because the dash lights didn’t dim. I was told “according to Workhorse” the dimmer switch is made to work with the additional lights that a coach manufacture would add, Thor did not put enough (any) load on the dimmer switch to have the dash lights dim.

If one calculates the wattage draw on a 10 ohm resistor on a 13.8v circuit it would show you have added a 19 Watt load to this circuit (he could have used a 10 ohm 25 watt resistor).
http://www.talonix.com/shop/item.aspx?itemid=8678

That’s about equal to one 1156 automotive light bulb.
http://www.bulbs.com/espec.aspx?ID=9654

I think I’ll put a 2 amp fuse (Inline Fuse Holder for 5x20mm Fuses from RadioShack, just to protect the dash lights) spliced into the green wire before the resistor.

If anyone does this before I get my RV out for the summer, let me know the wire color for the dimmer switch on the Serrano.

Calculations…
E (Voltage) squared divided by R (resistance in ohms) = Watts
13.8v * 13.8v / 10 ohm = 19 Watts
P /E = I
19 watts /13.8 v = 1.4 amps