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Discussion Starter #1
I've skimmed many a 3G and wiring threads, but will still apologize in advance for the answer to this question probably being previously discussed.

68 XR7 w/ 66 Mustang 289. I wired up a 3G just like described on the big 3G thread, provides plenty of juice to the system for my stereo upgrades. Only issue i have now is when I switch on my headlights only the LH headlamp works and my front parking lights go out. All parking lights work by just themselves and turn signals work all the time.

Could be a ground issue somewhere, but lights worked before 3G swap and that's the only wiring I have changed since. Thought it might have been as simple as a bad headlamp but plugging in a new one doesn't fix anything. Any headlamp wiring diagrams or advice welcomed, thanks!
 

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Check your grounds as these cars require a really nice clean ground. Trust me I have gone through this a few times. The only other issue I had with my light that was like this was a bad headlight switch. I'd say these would be the first 2 things to check if all you did was the 3G swap and checked that over.
 

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Discussion Starter #4
In general i cleaned up my grounds when i did the 3G swap, even added a battery to chassis ground. If the headlights have any specific location for grounds let me know. As far as the high beams, with those on I get all four headlamps working but still no front parking lights. So the bulbs are all good, seems like this would also mean the headlamp switch is good too? Does anything with the headlamps run around the alternator/ignition solenoid?
 

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As Leon said in his post above, the front parking lights does not illuminate when the headlights are on, it wasn´t until 69 or 70 that the front parking lights works along with the headlights
 

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your low beam is blown on the headlight that does not illuminate

Install the RH bulb on the LHS but don't install the one you remove from LHS. If the LH one works when you turn the lights on, then the bulb you have removed is blown

The parking lights do not illuminate when the headlamps are on

The headlamp circuits don't go near the charging circuit
 

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Ha, well so much for not looking like a rookie...I never knew the parking lights didn't run with the headlamps!

I'll try swapping things around to check the headlamps out. Only thing i still don't understand is if my low beam is out on the RH headlamp how does it then work on high beams? (i get all four lights on high beams) I thought it was a single stage bulb...and the only the other set of lights performed the high beam work.

And can you get non-halogen lights from a local auto store?
 

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Outboard bulbs are dual filaments that share a ground. Low beam uses one filament, high beam the other. You should have four bulbs lit on high.

Ha, well so much for not looking like a rookie...I never knew the parking lights didn't run with the headlamps!

I'll try swapping things around to check the headlamps out. Only thing i still don't understand is if my low beam is out on the RH headlamp how does it then work on high beams? (i get all four lights on high beams) I thought it was a single stage bulb...and the only the other set of lights performed the high beam work.

And can you get non-halogen lights from a local auto store?
 
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