Neutral/Oil Indicator Lights
 

Changed out all dash bulbs with LED's, and Neutral/Oil indicators stopped functioning.

Turns out HD wired the 2 sockets reverse (positive to can, negative to bottom pin).

Is there a particular reason they did this? It goes against standard wiring practice for bulb sockets. They are isolated 2 wire sockets so I don't understand why they would have did this.

Asking because I'm thinking of switching the wiring to standard configuration so I can use LED's for entire dash.

Thanks.

The reason the neutral switch and the oil pressure light sending unit are wired that way is so that the switch when activated will connect to ground.

Otherwise it would need to have a power wire going to the switch, then a wire from the switch to the bulb socket (later neutral switches are wired this way), since the bulb sockets are so close to a power source, it makes it a simpler way to connect.

In addition, if the wiring to the oil pressure light develops a short or the wire is severed, the oil light will come on.

An oil light illuminated when there is actually oil pressure is better than an oil light that does not come on when the pressure is low.

What is the problem about using an led for these bulbs, why can`t you just swap the wire on the led around?

Thank you Dan89FLSTC.

I get that the ground is switched in both circuits. Went over schematic to understand circuit before checking. Multimeter showed the reverse polarity to the sockets.

Was just wondering if there was a rational reason (safety or something like that) as to why HD decided to wire the can of the bulb positive and the pin negative, since they could have wired it either way and it would work just fine. Standard electrical practice is the can is -/neutral and the pin is +/hot.

There is no problem, and as I could see no reason other than an arbitrary choice on HD's part, I just reversed the wiring to the bulb sockets and now have a full compliment of LED's in my dash.

Thanks again Dan.

BTW this is on a 93 FXSTC.

Deleted...

Just either follow the wires and reverse them at the connector or cut and splice. It was probably a Friday or Monday build.

Hahaha! Never thought of that! :icon_laugh:

Already made the modification. Works fine.