Headlight/relay upgrade (w/o splicing into original harness)

[t_chelle16]

I'm not really ready to completely re-wire my mustang, but I'm tired of not being able to see at night. Sadie's high beams are just a tiny bit brighter than mom's Cherokee's low beams. And apparently, I've been driving around for a couple of weeks with my high beams on (tach blocks the indicator on the dash) and apparently no one has noticed. So, I decided to go ahead and do the relay thing so I can install some Sylvania Silverstars.

I started out intending to do it like in these write-ups:
http://midnightdsigns.com/james/headlights.htm
http://humanspeakers.com/audi/headlight-simple.htm

But as my dad and I started going through the process of installing them, it sort of evolved and he figured out a way to hook everything up so that I don't have to splice into the existing wiring harness.

First, I was getting ready to order the relays/sockets when Dad suggested I set it up with 4 relays (left high, left low, right high, and right low would all have separate relays). It's probably a bit overkill, but the relays are only a couple bucks each and if one relay goes out I wouldn't lose both headlights. So I ordered 4 relays (30-amp Bosch Relay #330-070) and 2 double sockets (Relay Socket (dual) #330-078).

We started working on it today (Dad gets credit for helping me out quite a bit. He has a lot of electrical experience and I have almost none).

The first thing I did was label all the wires to make things a little easier when I got out to the car (the sockets had an extra wire, so I just removed it - the red wires):


Also, the way the sockets were set up, the white & yellow wires went from plugs on one socket to plugs on the other. You can kind of see it in this pic:

I needed them to be separate (one for high, one for low) so I just pulled the plug out and separated the wires.


For the wires that go from the relays to the headlights, we used the sockets from old Sadie's headlights and ran wires straight from those to the relays (the online write-ups have you splice into the existing harness). And for the wires that are supposed to go from the dimmer switch to the relays (again, the online write-ups have you splice into the existing harness) we have put blade connectors on the ends of the relay wires and they will plug into the original headlight socket (making it act as the splice).

We got rained out today so I haven't completely finished, but I should be able to get the rest done and take some pics tomorrow. But for now, I drew up a very simple schematic to sort of show what we've done (be kind, I've never drawn a schematic before).

Oh, and I forgot to put it in the diagram, but I will be putting in some fusible links in the power wires that go to the battery.

-Chelle

 

[Cobain03]

im running silverstars just a plug and play situation. i'd love to go HID tho

 

[19stang66]

wow, nice write up. I'll keep this thread bookmarked for the future! Thanks chelle.

 

[t_chelle16]

im running silverstars just a plug and play situation. i'd love to go HID tho

I didn't even try seeing if I could just run the silverstars with the stock wiring. I figure it's a cheap upgrade and better in the long run so why not go ahead and do it. I will eventually re-wire it again because my wire colors don't match up like they should. After we decided not to hack into the harness and I realized I'd need more wire, I didn't feel like running to the parts store yet again so we just used the wire I already had. So when I re-do it (when I go to swap out the engine & re-wire the whole car), I'll get the correct colored wires, but for now, I'm just going to draw another schematic so I know what colored wire goes where.

wow, nice write up. I'll keep this thread bookmarked for the future! Thanks chelle.

Happy to be helpful.

-Chelle

 

[bnickel]

chelle, another thing you might consider is switching to a 69 or later headlight switch as it has a built in circuit breaker in case the system draws too much amperage and overheats the switch, the circuit breaker will keep it from melting. you most likely won't have any problem since you are using relays but it's good insurance anyway

 

[t_chelle16]

I thought the 67 switch also had the circuit breaker.

-Chelle

 

[yeloxr7]

I bought a relay kit from Summit Racing. it was strictly plug-and-play using one of the factory headlight plugs. The most time-consuming part was removing the yellow wire sheathing and replacing it with black flex loom covering.

2-light kit: http://store.summitracing.com/partdetail.asp?autofilter=1&part=AMC-509102&N=400375+115&autoview=sku

4-light kit: http://store.summitracing.com/partdetail.asp?autofilter=1&part=AMC-509103&N=400375+115&autoview=sku

 

[t_chelle16]

Cool. I was just thinking it would be a nice thing to market because you don't have to cut into your harness. I didn't realize it was already available.

-Chelle

 

[1966conv]

Another place that specializes in mustang relays

This place specifically makes to relays for vintage mustangs, I have sets on 3 of my mustangs.

http://www.modernvintageauto.com/

 

[mustangdave]

Does the Summitt kit have any instructions? Looks great. Good job Chelle, but anytime I can get a plug-and-play, I'm all for it.

 

[t_chelle16]

Does the Summitt kit have any instructions? Looks great. Good job Chelle, but anytime I can get a plug-and-play, I'm all for it.

True. If I had know there was already a plug-and-play kit before I started, I probably would have gone that route. But even doing it from scratch isn't too bad. I've been fighting the rain all day, but I'm almost done. Just got to run to the store to get some more connectors and more heat shrink.

-Chelle

 

[yeloxr7]

Does the Summitt kit have any instructions? Looks great. Good job Chelle, but anytime I can get a plug-and-play, I'm all for it.

Yes, it comes with pretty good instructions. But once you have the thing laid out, it is obvious where most of the connections go. At least it was to me. There is enough wire length to route the harness together with the factory wiring. I just zip-tied them together.

 

[yeloxr7]

To take best advantage of the benefits that come with using the relay harness, you really need to get some of these: http://www.performanceproducts.com/...a+Vision+Plus+Halogen+Headlight&vehicle=16052

 

[bnickel]

I thought the 67 switch also had the circuit breaker.

-Chelle

i could be wrong but i don't think it did, or maybe it was rated lower, i can't remember for sure. anyway i'm pretty sure the 69 unit is an upgrade from the 67 switch. hopefully someone will correct me if i'm mistaken

 

[dennis112]

i could be wrong but i don't think it did, or maybe it was rated lower, i can't remember for sure. anyway i'm pretty sure the 69 unit is an upgrade from the 67 switch. hopefully someone will correct me if i'm mistaken

69' is the upgraded one because they have quad headlights which results in more power draw.

Might need to do a little rework on the front mounting bracket, at least for a 65-66. It looks easy enough if you have an original switch to compare to.

 

[t_chelle16]

Well, I finished up this afternoon and just got back from band rehearsal (driving at night) and the headlights are great. Now I feel totally comfortable doing the speed limit at night (before, I always went a lot slower at night).

Couple more pics.

The relays:

Not super interesting, but his is one of the original plugs which now links the dimmer switch to the relays.

-Chelle

 

[t_chelle16]

i could be wrong but i don't think it did, or maybe it was rated lower, i can't remember for sure. anyway i'm pretty sure the 69 unit is an upgrade from the 67 switch. hopefully someone will correct me if i'm mistaken

69' is the upgraded one because they have quad headlights which results in more power draw.

Might need to do a little rework on the front mounting bracket, at least for a 65-66. It looks easy enough if you have an original switch to compare to.

Thanks. When I get around to rewiring the whole car, I'll probably pick up one of the 69 switches, then.

-Chelle

 

[rbohm]

actually chelle, at this point dont bother with the upgraded switch unless you have to replace the switch anyway. since you are using relays now, the current carried by the head light switch is miniscule compared to what it was before. also as far as i know, all head light switches made since the late 50's have circuit breakers built into them. however the 69 mustang had a heavier duty switch due to the four headlights over the earlier two headlight system.

 

[67CoupeDriva]

Both switches have a breaker, the 69 is higher amp b/c of the quad lights. So it's like putting a 20A breaker in your box at home to replace a 15A -- the wiring may not be rated to safely handle the load.
However, it's a moot point as stated above as now the system only has to handle a tiny fraction of an amp to trip the breakers, which will handle the actual headlamp power draw.
4 relays is definately overkill - but since you've already done it you do have redundancy in the unlikely event that one of them fails.
I did this myself from scratch and it's very easy, I don't know what the kits cost but it was a 45 minute project so don't pay too much!

 

[t_chelle16]

actually chelle, at this point dont bother with the upgraded switch unless you have to replace the switch anyway. since you are using relays now, the current carried by the head light switch is miniscule compared to what it was before. also as far as i know, all head light switches made since the late 50's have circuit breakers built into them. however the 69 mustang had a heavier duty switch due to the four headlights over the earlier two headlight system.

Both switches have a breaker, the 69 is higher amp b/c of the quad lights. So it's like putting a 20A breaker in your box at home to replace a 15A -- the wiring may not be rated to safely handle the load.
However, it's a moot point as stated above as now the system only has to handle a tiny fraction of an amp to trip the breakers, which will handle the actual headlamp power draw.

That's pretty much what I was thinking before. I though the 67's had the circuit breaker because that's what makes the lights cycle on & off if you try halogens/other more powerful lights w/o the relays.

4 relays is definately overkill - but since you've already done it you do have redundancy in the unlikely event that one of them fails.

Yeah, I know it's overkill, but the 2 extra relays and extra dual socket cost a whopping $6. So it's not like I spent a fortune going with 4 as opposed to 2.

-Chelle