I need to know what is wrong with pin 3 of my factory plug. just talking about oe wiring. i cant even put a regular bulb in it anymore without shorting pins 1 and 3 because they are both positive. Once i fix this pin 3 issue, i will post a picture and diagram for my custom harness wiring with an extra fuse/relay box install. those plug and play units are over priced

 

yes it is a 2001, i have a service manual and basically from what i can tell {their diagrams are had to read with the whole quad and without quad headlight markings everywhere} the dimmer switch (the stalk for brights) controls that third pin.

 

i am using the 3 inch mini 55w {purple box}. but even if i wanted to use your harness i couldnt because pin 3 is malfunctioning.

 

Not malfunctioning. Switch etc provide the ground path. Power to the lamps is always hot.

 

You are telling me pin 3 and pin 1 should be hot at all times? because that means pin 1 {common} and pin 3 Hi beam would short out even with the truck off. when i switch on low beams i get ground from pin 2, 1 and 3 stay hot; when i switch hi beam on then pin 1 goes from hot to ground and pin 2 has no continuity pin 3 stays hot.

Normal operation before it started acting like that. Truck off: pin 1 hot pin 2 off pin 3 off, Low beam on; pin 1 hot pin 2 ground pin 3 off, Hi Beam on; pin 1 ground pin 2 off pin 3 hot.

 

Looks power power is fed from Violet wire on left side, violet with red trace on right side. Do you have quad headlamps?? (sport truck?)

If you are seeing power anywhere else, (assuming unplugged from BOTH headlamps, that means all four on a sport truck) you have a short somewhere.

 

[QUOTE=HeyYou;3590011]Looks power power is fed from Violet wire on left side, violet with red trace on right side. Do you have quad headlamps?? (sport truck?)

If you are seeing power anywhere else, (assuming unplugged from BOTH headlamps, that means all four on a sport truck) you have a short somewhere.

so the left wire is pin 1 [common] and switches from hot to ground when hi beam activated, middle pin 2 is low beam ground, right pin 3 is high beam hot
pin 3 should only go het when activated by the dimmer switch i believe. So if my high beam hot wire is staying hot and not switching off when high beams are turned off would it be a faulty dimmer? also it is a non sport. im not the best at reading the dodge wiring diagrams due to all the with and without quad headlight markings that dont really make sense to me, the problem is both 9004 plugs

 

Two or four lamp system?

 

2 lamp system.
Before i tested my harness:
pin 1 is R/O and is hot when vehicle is off and when low beams are on, Ground when hi beam is on
Pin 2 V/W is ground only when low beam active
pin 3(V/R) is hot only when hi beams are on
After i tested harness
Pin 1 hot when vehicle is off and when low beams are on, Ground when hi beam is on
Pin 2 ground only when low beam active
Pin 3 always hot

 

Because of the melting headlight switches on older models the headlights on 99+ are "ground switched". The pin on the bulb that is typically used for ground is powered directly from the PDC and the headlight/hi beam switches connect either filament to ground. Incandescent light bulbs don't care which way the current flows but aftermarket LED/HID do so that is one thing to consider. In stock form with the lights off you will measure battery power on all three headlight pins, that is because one pin gets power (see above) and the other two are just dangling unconnected. The filaments are very low resistance and a voltmeter places no load on a circuit so it just reads 12V on the other side of the filaments. Switching on either filament connects that side to ground (no voltage reading) but the other filament is still unconnected and still reads 12V.

Edit: I think I know where the confusion is coming from. What I wrote above is correct but the high beam indicator in the dash works the same way. Even with the headlight bulbs removed there will be 12V on the high beam side with high beams off just getting there a different way through the dash indicator light.