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Electrically it shouldn't matter which side is which on that bulb. If the bulb has two contacts on the end (which I think it should) then there is no difference at all, if it's only got the single contact on the end and the barrel is the other contact, then the barrel should be the "ground"
M
As I recall, on my 72 the white wire is the "ground" through the door switches and the orange is constant power, probably the red on yours there. but again, shouldn't matter at all
M
In regular cars it matters. Screw the housing to the body and the housing is grounded. Fiberglass is a lousy ground path, so you can get away with grounding either one. But might as well ground the correct one.
It'll matter if you ever put an LED in that socket. I have warm LEDs in my cars, it looks stock, feels period, gives more light, and uses less current.
The LED will care which way the current flows, so why not do it correctly, with positive on the pin, ground on the shell?
I think it’s funny when you get a response like "It doesn’t matter". In life there is a right way and a wrong way to approach every task. Bubba will always tell you differently.
Well since that's a #90 bulb, which is a double contact, symmetrical bayonet base bulb back there (up to about 76 or 77), which of course means it can be put in either orientation, I'd be happy to know which of the two contacts the the ground and which is the positive
So if you guys want to explain how to connect one of those wires to the bulb case (shell), which isn't a ground on these bulbs, and which one of the two pins is the ground and which is positive, go for it.
In the mean time me and Bubba will wait
Originally Posted by mjmike
Yes, It does matter!
The outside of the bulb (The part that hold the bulb in place) is always ground.
Originally Posted by Bikespace
It'll matter if you ever put an LED in that socket. I have warm LEDs in my cars, it looks stock, feels period, gives more light, and uses less current.
The LED will care which way the current flows, so why not do it correctly, with positive on the pin, ground on the shell?
Originally Posted by mjmike
I think it’s funny when you get a response like "It doesn’t matter". In life there is a right way and a wrong way to approach every task. Bubba will always tell you differently.
Ok, the next step would be to take a digital meter and check for continuity between the side of the bulb and one of the two pins. The one that has continuity against the side of the bulb will be your ground.
If you find that you don't have continuity to the side of the bulb, I would then find a wire diagram for that year and follow GM's OE wiring specifications for this location.
Ok, the next step would be to take a digital meter and check for continuity between the side of the bulb and one of the two pins. The one that has continuity against the side of the bulb will be your ground.
If you find that you don't have continuity to the side of the bulb, I would then find a wire diagram for that year and follow GM's OE wiring specifications for this location.
On a #90 bulb, the shell does not need to be connected to either pin, and on the two bulbs I just checked it isn't, Which wire is ground (the white in this case) is not relevant as the neither the bulb or socket is polarized. so as Bubba and I stated above, either wire can go into either hole in the socket so................... "It doesn’t matter"
M
Wow! Story checks out. Bottom pins are + and -, shell is not connected. The bayonet studs are symmetric, so the same bulb can be put in in either orientation.
#90 bulbs have lots of replacement options: BA15D 1076 1142 68 90 1004 1130 1158 1176 1178.
So I was completely and utterly wrong. Absent of contradictory evidence in the AIM, or ringing it out as mjmike suggested to ensure the shell isn't connected to one of the pins, it turns out it really doesn't matter!
If the wires only go to the pins on the bulb, it makes no difference. But, if one of the wires goes to one pin AND the metal casing, that wire would be for negative (-) side of the battery.
