9007 Wiring?

[fangle]

This should not be a difficult question, but I'm not getting the answer I expect.

I'm preparing to do the sport headlight conversion on my '02 Ram 2500 (think '94-'01 body style). I have the replacement headlights, which use a 9004 and a 9007 bulb. I'm preparing to make the relay harness needed and decided to check my notes on the bulb wiring. I am getting an unexpected result.

9004 bulb is acting as expected. BLK is ground, YEL is low beam, and BLU is high beam. Using my portable jump box and the headlight socket (no harness, relays, etc.) I get:
BLK-YEL 3.6A
BLK-BLU 5A
This makes sense, the high beam should have a higher current draw. The 9004 bulb used is the generic bulb that came with the headlight, I will change to a good bulb later.

9007 bulb should be BLU is low beam, YEL is ground, and BLK is high beam. However, testing with the jump box I get
BLU-YEL 5A @ 12.1V
BLK-YEL 4.3A @ 12.2V
This looks like the high and low beams are reversed. I tried a Philips 9007XV and got the same thing:
BLU-YEL 4.9A @ 12.1V
BLK-YEL 4.2A @ 12.2V
Judging by eye it is very hard to tell the difference, but the higher amp reading connection looks a little brighter. This would point to my documentation being backward for the 9007, but it is the same everywhere I look.

It appears that the black lead goes to the 9007 filament closest to the center of the bulb. The blue lead goes to the filament offset to the outer edge of the bulb, with a larger wire diameter and wider spacing between the turns. The yellow does connect to the common connection inside the bulb.

Why do the high and low beams appear reversed on the 9007 bulbs compared to the published documentation? I do not expect to see the higher current draw on the low bean side.

Thanks!

 

[lightfooted]

Because Automotive manufacturers? Im not sure what you mean by everywhere, a quick Google search showed me that in fact they are not the same wiring (same plug tho)...in so many places it would be silly for me to point to them. My only guess as to why is simply because the 9004 is older...the first Halogen lamp used in North America.

 

[fangle]

Im not sure what you mean by everywhere, a quick Google search showed me that in fact they are not the same wiring (same plug tho).

I was not clear - edited my post. My 9007 measurements don't appear to match the published info on the 9007 bulb, with the higher current appearing to be on the low beam not the high beam as expected. I do not know why this would occur.

 

[-Virgil-]

In the view as shown in your 9007 photo, the correct pin-out is yellow ground, black low beam, and blue high beam.

Why do the high and low beams appear reversed on the 9007 bulbs compared to the published documentation?

What documentation are you looking at? According to the official document (page 5), the pin-out is as I've described it.

Also, while you're technically correct about the pin-out of the 9004 bulb, it's very important that you not hook its low beam filament to power. Those Dodge Ram Sport headlamps use only the high beam filament of the 9004 bulb; there are no optics in the inner compartment of those lamps to provide a low beam or any other useful distribution of light from the 9004 low beam filament (both low and high beam filaments are used on the outer 9007).

 

[fangle]

Thanks Virgil! I did not know why my measurements don't match what I found online. All over the web there are two images that seem to be repeated in every discussion on 9004/9007 bulbs. This page is one example that contains both. https://ѕpаrkѕmіth.com/blоgѕ/nеwѕ/dо-yоu-knоw-the-dіffеrеncе-bеtwееn-9004-and-9007-bulbѕ

Yes, the 9004 gets high beam only. I've read the discussions here with your good advice, Mr. Stern's write-up, as well as cross-referenced the factory wiring diagrams while I saved the cash to do the swap. For those doing similar work, I found Bosch 0 332 019 150 relays (SPST with dual 87 terminals) under $3 at Rock Auto. I will have four of them for the lights: One for each low beam, one for the 9004 high beams, and one for the 9007 high beams. I wanted diversity in the wiring so no single relay could take out all the lighting. Each is an individually fused circuit.

 

[-Virgil-]

Ahhhhhh, that image! I think those first appeared years ago in Candlepower's tech library, and yeah, that 9007 terminal ID has been wrong from the git-go. If there was ever any chance it would get fixed, that's gone now; I just got word yesterday that Candlepower is going out of business. The rest of the info sheets here are good fun, in a sort of "Remember what the '90s were like on the internet?" way.

I found Bosch 0 332 019 150 relays (SPST with dual 87 terminals) under $3 at Rock Auto.

Great price, though I usually prefer to use the 0 332 019 155 (with spike-suppression diode) just to be cautious especially on later-model cars with computer controlled headlight circuits. Not an issue on your truck, though I think the Ram that replaced it is such a model.

I will have four of them for the lights: One for each low beam, one for the 9004 high beams, and one for the 9007 high beams. I wanted diversity in the wiring so no single relay could take out all the lighting.

That all makes sense. It's always a balancing act between what could happen if a relay fails (gets worse as more and more lights are controlled by any single relay), versus the likelihood of a failure (gets worse as the circuit includes more and more relays, connections/terminals, and other points of potential failure).