Direct wiring the headlights

[kaboom10]

I bought a prewired harness for my F-150. It uses relays to to provide direct battery voltage to the headlights triggered by the headlight switch. Snapped right into the existing wiring harness. WOW what a difference. I should have measued the voltage at the connector to see what it was before. I found a schematic and could beat the price if I built it myself but found a harness already built even cheaper.

 

[Steve S]

What is the difference in volt drops between the stock and aftermarket wiring?

 

[HTSS_TR]

Good read on adding relays to headlight circuit from Daniel Stern

http://www.danielsternlighting.com/tech/relays/relays.html

 

[kaboom10]

I didn't test for it. The lights are noticeably brighter. You know kida like when you see the lights on with and without the alternator charging.

 

[kaboom10]

I think that's where I got the idea. I just couldn't see paying his price when I found a plug-in harness made just for my application for half as much.

 

[Steve S]

that is an improvment.

 

[VWguy]

Voltage drop is so important when working on older cars. I have a '71 VW bug I picked up from my old supervisor for $200. I did not want to pour a lot of money/time into this car (just safety related stuff for now). Well the headlights were dim, so I replaced the sealbeam units with halogen sealbeams from the Pick A Part but the lights still were dim. I installed a used set of H4 lights I had but was not happy with the light output. So, I got out my trusty DVOM and had a 2+ volt drop between the battery and the fuse box. I bought lengths of 10ga wire, inline fuses, relays, connectors and bypassed the main harness for the headlight circuit only. The after repair resulted in an acceptable .2 volt drop from the battery to the back of the headlight. Lights are now bright but the cheapo off shore H4 housings have a very poor beam projection, even with Sylvania Xtravision H4's. I have learned a lot from the quality and very informative site from Daniel Stern. I have even bought products from him. Bill