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Can't dip high beams

1K views 11 replies 5 participants last post by  EOD Guy 
#1 ·
'34 ford, Ron Francis wiring, 1,400 miles, Ron's dash switch, Ron's foot H/L switch. No relays, just the foot switch to the headlamps.

It was working just fine until a few nights ago. High beam/low beam... no problem. the other night I stepped on the switch to dip the highs and nothing happened, the highs stay on. The switch makes noise... nothing changes. The blue dash light stays on too.

So I ordered a new foot switch, same thing. I can't get the highs to turn off. it can't be the switch, but the switch only energizes either the low or high, right?. With the switch unplugged, neither headlamp lights.

I jiggled every inch of the wiring, can't get the lights to even flicker.

Any thoughts?
 
#3 ·
lost ground

One of the headlights has lost it's ground.
The juice now flows in series thru the other headlight to ground which causes the bulbs to light but dimmer than normal.
The dash light also provides a path to ground.
When you switch to low beam the dash light will remain on.

vicrod
 
#4 ·
Vic has a good point, it could also be chaffed/shorted hi/low beam wires or connector.

Disconnect the head light connectors from the head light bulbs and verify you have good grounds at the connectors........ If the grounds are good.....

Unbolt the dimmer switch, determine which wire is the pwr supply wire, leave that connected, remove the other wires (Hi/low beam) use a multimeter and verify you have pwr out on each of the other terminals. One should be dead and then pwr up as you switch the dimmer switch, and the other should go dead etc..... eliminates the switch, just because it's new doesn't mean it's good. If the switch is good......

Hook up one of the wires ie... hi beam wire and verify the head light(s) lights, then goes out after depressing the dimmer switch.......... eliminates the wiring to those light(s)

Remove the Hi beam wire and hook up the low beam wire to the same terminal you just disconnected, and see if the low beams lights, then goes out etc.......... eliminates the wiring to those light(s)
 
#5 ·
Could also be a crossed filament in one of the Hi beam bulbs, cross feeding the low and also back feeding from the low to the high beams.
Try unplugging the hi beam bulbs one at a time to see if/when the problem disappears.
 
#7 ·
Found it.

You're not gonna believe this. The bulbs are fine, the plugs on the other hand, melted pretty good - Jeeeezus.

Yea, I was getting a short alright.

I said in my OP that I got my wiring from Ron. I cannot state that these plugs came from Ron, I genuinely don't know for sure, but I'm going to send these to them so they can check their supplier.
 

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#11 · (Edited)
Are both headlight connectors melted?

vicrod
Yes. The short only happened on one of them crossing the low and high beam wires rendering the hi/lo switch useless. The clips in this particular set were spring loaded so when the plastic softened the wire crimps were forced towards each other. The new ones installed yesterday clamp the wires onto the bulb's tangs independent of the plastic part.

Honestly, the plastic housing holding the clips is not necessary. The wires can be clipped to the bulb's tabs just fine individually, as long as they're marked G, L, H.
 
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