Headlight Relay Harness
Dec 10, 2012 | 01:39 PM
#102
Registered User
Joined: Sep 2007
Posts: 8,380
Likes: 871
From: San Francisco East Bay
Richard: I hate to be discouraging, but if you are asking these questions, you will be better off having someone else do whatever wiring you're thinking of.
The wire has to be long enough to reach where ever you're going. The electrons can't see the insulation, and don't care what color you use. That's for your benefit, and you can pick Chartruse if you're into that.
But the gauge of the wire matters, as does the types of connectors used and the capacity of the relays. Most of which was covered earlier in this thread.
Stick to that with which you feel comfortable.
The wire has to be long enough to reach where ever you're going. The electrons can't see the insulation, and don't care what color you use. That's for your benefit, and you can pick Chartruse if you're into that.
But the gauge of the wire matters, as does the types of connectors used and the capacity of the relays. Most of which was covered earlier in this thread.
Stick to that with which you feel comfortable.
Jan 15, 2013 | 07:41 PM
#105
Registered User
Joined: Jan 2012
Posts: 289
Likes: 2
From: Tacoma
Assembled a headlight relay harness today. I drafted up a quick (don't laugh) schematic and got to work:
All cable is 12awg THHN except for the H4 pigtails...they're 12awg stranded but not THHN rated. I should have taken pics of the process but when I'm in go mode I just go. Here's the final product:
(2) 30A relays
(2) Female H4 pigtails
12awg THHN
Ring terminals for the battery connections
Butt connectors for the H4 pigtails
Male spade terminals for the factory H4 connector
Female spade terminals for the relays
1/2" wire loom
Electrical tape to wrap the loom
If you want to go all out, you could use a male H4 pigtail instead of male spades to plug into the factory H4 connector and relay pigtails instead of female spades to plug into the relays.
I ended up running a dedicated ground back to the battery (zip-tied to the loom every 6") afterwards. I figured with this much effort I might as well run the extra cable. Copper conducts better than steel and I didn't want ANY weak links.
Went for a quick drive tonight but I need to re-aim the housings. Even with the beams all over the place it's amazing how much brighter good halogens are vs. HIDs in halogen housings. One of these days I'll install a projector retrofit like this and go back to HIDs but for now halogen is fine. 55w/100w bulbs by the way.
All cable is 12awg THHN except for the H4 pigtails...they're 12awg stranded but not THHN rated. I should have taken pics of the process but when I'm in go mode I just go. Here's the final product:
(2) 30A relays
(2) Female H4 pigtails
12awg THHN
Ring terminals for the battery connections
Butt connectors for the H4 pigtails
Male spade terminals for the factory H4 connector
Female spade terminals for the relays
1/2" wire loom
Electrical tape to wrap the loom
If you want to go all out, you could use a male H4 pigtail instead of male spades to plug into the factory H4 connector and relay pigtails instead of female spades to plug into the relays.
I ended up running a dedicated ground back to the battery (zip-tied to the loom every 6") afterwards. I figured with this much effort I might as well run the extra cable. Copper conducts better than steel and I didn't want ANY weak links.
Went for a quick drive tonight but I need to re-aim the housings. Even with the beams all over the place it's amazing how much brighter good halogens are vs. HIDs in halogen housings. One of these days I'll install a projector retrofit like this and go back to HIDs but for now halogen is fine. 55w/100w bulbs by the way.
Jan 29, 2015 | 05:55 PM
#109
Registered User
Joined: Jan 2015
Posts: 2
Likes: 0
Assembled a headlight relay harness today. I drafted up a quick (don't laugh) schematic and got to work:
All cable is 12awg THHN except for the H4 pigtails...they're 12awg stranded but not THHN rated. I should have taken pics of the process but when I'm in go mode I just go. Here's the final product:
(2) 30A relays
(2) Female H4 pigtails
12awg THHN
Ring terminals for the battery connections
Butt connectors for the H4 pigtails
Male spade terminals for the factory H4 connector
Female spade terminals for the relays
1/2" wire loom
Electrical tape to wrap the loom
If you want to go all out, you could use a male H4 pigtail instead of male spades to plug into the factory H4 connector and relay pigtails instead of female spades to plug into the relays.
I ended up running a dedicated ground back to the battery (zip-tied to the loom every 6") afterwards. I figured with this much effort I might as well run the extra cable. Copper conducts better than steel and I didn't want ANY weak links.
Went for a quick drive tonight but I need to re-aim the housings. Even with the beams all over the place it's amazing how much brighter good halogens are vs. HIDs in halogen housings. One of these days I'll install a projector retrofit like this and go back to HIDs but for now halogen is fine. 55w/100w bulbs by the way.
All cable is 12awg THHN except for the H4 pigtails...they're 12awg stranded but not THHN rated. I should have taken pics of the process but when I'm in go mode I just go. Here's the final product:
(2) 30A relays
(2) Female H4 pigtails
12awg THHN
Ring terminals for the battery connections
Butt connectors for the H4 pigtails
Male spade terminals for the factory H4 connector
Female spade terminals for the relays
1/2" wire loom
Electrical tape to wrap the loom
If you want to go all out, you could use a male H4 pigtail instead of male spades to plug into the factory H4 connector and relay pigtails instead of female spades to plug into the relays.
I ended up running a dedicated ground back to the battery (zip-tied to the loom every 6") afterwards. I figured with this much effort I might as well run the extra cable. Copper conducts better than steel and I didn't want ANY weak links.
Went for a quick drive tonight but I need to re-aim the housings. Even with the beams all over the place it's amazing how much brighter good halogens are vs. HIDs in halogen housings. One of these days I'll install a projector retrofit like this and go back to HIDs but for now halogen is fine. 55w/100w bulbs by the way.
JR
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