[alfa] re: Relay in headlight circuit

[Joe Elliott <jee@xxxxxxxxxxxxxx>]

I just realized that I forgot to answer the second part of your 
question--parts.  Relays, etc. are available from Dan Stern, as 
somebody already pointed out, as well as other such vendors, like 
Susquehanna Motorsports (http://www.rallylights.com) and Aardvark 
International (http://www.talbotco.com), as well as local retailers. 
The conventional wisdom is to avoid off-brand relays from local auto 
parts chains in critical systems like headlights.  However, Hella, 
Bosch, etc. aren't cheap, unless you pull them out of the fuseboxes 
of BMWs in junkyards, and I'm not sure that's any safer than buying 
junk parts from AutoZone.  What's most important is that you get 
relays rated appropriately for the current you'll be drawing.  Two 
100W high beams could draw close to 20A if your electrical system is 
heavily stressed.  While I referred to generic 4-terminal relays in 
my previous message, 5-terminal relays with dual outputs can be handy 
so you don't have too many wires crammed into one connector (some 
cars have 4 bulbs on the high beam circuit, for example).  But be 
aware that many 5-terminal relays feature a normally-closed terminal, 
which isn't what you want, unless you want to have your fog lights 
switched off automatically whent the high beams come on, or something 
like that.  Some people like OEM-style relay holders.  I don't, but 
they're available from the vendors mentioned above.  I think it's 
worth noting that for relay holders to do you much good, you have to 
have female spade connectors that have the tab to secure them in the 
relay holder.  It's for lack of these that I don't mess with relay 
holders, but it looks like Susquehanna now stocks them.  Fuse holders 
with heavy gauge wire can usually be found locally, but I'm sure the 
afformentioned web sites sell them too.  What I'd really like to find 
to make this mod easier would be relays with built-in fuse holders, 
like those used on the Milano for the radiator fan and aircon 
compressor.  As for connectors, if you're upgrading a car from sealed 
beams, and you use the under-dash relay method, then you don't need 
any because the American lights your car came with use the same 
connectors as the European equivalents you're replacing them with 
(this compatibility doesn't apply to modern stuff like Complex 
Reflect 4 x H1 setups, or HID, which require entirely different 
wiring).  If you're putting the relays under the hood to accomodate 
higher-wattage bulbs or because you don't trust your car's original 
wiring, this is where it can get frustrating, at least if you're me. 
Spider drivers need not worry, because the three-connector plug for 
H4 lights (and American equivalents) is readily available.  Dan Stern 
will sell you a high-quality piece that I'm sure works well, but I 
dislike its non-OEM nature (the wiring harness attaches to the 
connectors with spring-loaded clamps rather than being crimped). 
Aardvark carries a very high-quality OEM-style plug with fairly heavy 
wire attached to it, which I would recommend, but I should warn you 
of Aardvark's Caribou-esque billing, shipping, and customer service 
behavior.  It looks like Susquehanna stocks both styles of H4 
connector, but I've never seen their parts so I can't say anything 
about design or quality.  Your local auto parts chain may carry them, 
as well, because it's the same plug as American sealed beams, except 
the cheap crap I bought from AutoZone won't fit the sealed beam, the 
H4, or any other headlight I've ever seen.  If you luck out and find 
cheap crap that fits, beware that the attached wires may not be 
adequate.  If you have a four-headlight system with H1 bulbs, the 
easiest thing to do is get an H4 plug and leave the third connector 
unused.  I believe this is what Dan Stern recommends.  I think that 
looks too unprofessional, and I actually ended up using individual 
spade connectors.  (I just have to make sure I don't mix them up, 
because H1 bulbs are polarized!)  The local auto parts store has the 
same BS parts that don't fit at all, and Aardvark, supplier of the 
finest H4 connector, will be happy to sell you an H1 connector for 
the same high price, but will send you the same non-fitting crap 
that's available at AutoZone!  And of course wire is available 
locally, as are normal spade connectors.  I think that about covers 
it for parts.

-Joe
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