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1968 CDV / 1970 FWB /1979 FWB / 1995 Eldo
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Discussion Starter #1
Hi, I posted this question in the electrical section, but received no responses so I will try it here too.

In an effort to boost headlight output, I was considering the installation of relays on my '68 Cad. Basically running power directly from the alternator/battery to the headlights through relays, using the stock light switch to activate the relays. I was going to install H4s, but was afraid it would be too much for the headlight switch. Plus, if I can achieve 13.5 volts to the stock lights (10.5 now)after installing the relays, I may not have to change out the lights. Anyone have any experience with the end result? Thanks!
 

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1977 Coupe (blue), 1977 Coupe (yellow), 1977 Coupe (green)
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1,493 Posts
I don't know why you would do this. The switch and the dimmer switch are hot leads to the head lights with only the fusible link as resistance. Check all your connections for possible corrosion before causing yourself more headaches. You could run the dash and interior lights on a seperate circuit if you are concerned about overload on the original switch. That is the only use of the built in rheostat.
 

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Orange And Purple Lights.
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6,632 Posts
^This.

If you are still concerned about output, yes, you can upgrade to H4 bulbs, HID lights or even LED housings, like those used to retrofit older Semi trucks if you choose.
 

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1979 Sedan deVille d'Elegance
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2014 ELR
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Relay power feeds are very common now for older cars. GM used marginal wiring, and full power goes through the switch. Relays will not only give you much more useable light, it will be safer. You can make your own harness, or buy pre-made for under $100.
 

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1968 CDV / 1970 FWB /1979 FWB / 1995 Eldo
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228 Posts
Discussion Starter #7 (Edited)
I will check into it further but it sounds like a good solution. I did clean all the connections when I installed the Silver Star Halogens, I did see improvement, but the lights are still yellowish. I looked at a wiring diagram for my '68 and did note that all the power for the headlights is in fact routed through the switch. I was concerned about installing higher wattage H4s in it for fear of ruining the switch, our melting the wires.

Relay power feeds are very common now for older cars. GM used marginal wiring, and full power goes through the switch. Relays will not only give you much more useable light, it will be safer. You can make your own harness, or buy pre-made for under $100.
 
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