Confused

[87ChevyR10]

Howdy,

I've been away for a while and I finally got the chance to replace the headlight switch. After doing so, I discovered my top beams are both hi/low and the lower lamps never turn on. I got to looking at the plug for the top lamps and they are 3-prong plugs while the bottom lamps are 2 prong plugs. Everything looks factory.

Now here's where my confusion kicks in. Why would Chevy use 3 prong plugs for the top lamps? If the bottom lamps are meant to be the hi-beams, why give the option for the top lamps to use both? Unless I am misunderstanding what I am seeing. The low beams have never worked since getting the truck. And up until this last weekend, anytime I tried using the hi-beams, my headlights would go dead.

So, yeah, I'm really confused over my headlight setup. I've been wanting to get the the single lamp bezels from LMC; and since I now know only the top pair of lamps work, I see no reason not to convert at this point. Plus, the new bezels would allow me to move the front signals.

Anyways, can anyone figure why my head-lamps are setup the way they are?

 

[89Suburban]

3 prong plug is for a 2 filament hi/low combination bulb. 2 prong is for single filament high beam bulb.

 

[87ChevyR10]

3 prong plug is for a 2 filament hi/low combination bulb. 2 prong is for single filament high beam bulb.

I understand that much. My confusion lies in the redundancy in the wiring. Why have the wiring for hi/low beam lamps on the top and only hi's for the bottom? In my case, I have no need for the bottom lamps, period. They never come on. I'd rather have all 4 lamps as low beams and the top pair for hi beams. As I mentioned before, all the wiring under the hood looks factory.

Do the bottom pair run on their own circuit/fuse?

EDIT: Does it matter if the bottom lamps are 3 pronged using the 2 prong plug? I know the bottoms work if the 3-prong plug from the top is used in them.

 

[bucket]

Umm... no use for the lower lamps? Are you serious? GM didn't put them there for looks.

If you have lights that don't work, either they are burnt out or you have a wiring problem. Period.

 

[87ChevyR10]

Umm... no use for the lower lamps? Are you serious? GM didn't put them there for looks.

If you have lights that don't work, either they are burnt out or you have a wiring problem. Period.

Would there be a difference if all 4 lamps where hi/low combo's?

 

[animal]

I would think it would not be legal to have all four headlights on for "low beams". Hence the reason for 2 for low/high and 2 that only come on for high.

 

[LB2387]

It wouldnt matter if all 4 bulbs were hi/low because the harness will only turn on the lower bulbs when the high beam circuit is activated anyways. You said that the lower bulbs will work when you plug them into the harness for the upper lights? If this is the case, your issue is either going to be in the wiring going to the lower lights or the high beam switch itself. There are not two seperate fuses for the low and high circuits. They both share the same fuse.

 

[87ChevyR10]

It wouldnt matter if all 4 bulbs were hi/low because the harness will only turn on the lower bulbs when the high beam circuit is activated anyways. You said that the lower bulbs will work when you plug them into the harness for the upper lights? If this is the case, your issue is either going to be in the wiring going to the lower lights or the high beam switch itself. There are not two seperate fuses for the low and high circuits. They both share the same fuse.

I recently replaced the hi-beam switch because it would cut out the lights and refuse to turn them back on.

I guess what I need to do is take my volt meter and see if the lower plugs are getting juice (when it gets warmer outside).