brake light issues, need advice.
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Senior User
Joined: Jul 2013
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From: Central Florida
brake light issues, need advice.
Got a strange issue with my rear taillights. Brake lights and turn signals work perfect with the head lights off. Turn them on and it seems like I'm not getting enough voltage. The taller of the two filaments on the 1157 bulbs seems to be lighting but real dull. Before I go on a goose hunt tracking the wires back into the cab I'd figured I'd ask see if there is a common problem. Maybe a place I should start?
Thanks
Thanks
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Senior User
Joined: Jul 2013
Posts: 225
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From: Central Florida
Also so I don't make another thread im looking for the fresh air vent that goes under the dash on the drivers side. Don't know what its exact name is but I haven't seen one in LMC or JBG.
Moderator & parts slinger
Joined: Feb 2007
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From: S/W Missouri, Polk county
Sounds like it time to replace the head light switch, but 1st clean all the grounds and contacts in the rear sockets.
Ck the condition of the brake pedal switch.
And you need part #19898 the a/c vent.
Ck the condition of the brake pedal switch.
And you need part #19898 the a/c vent.
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
Got a strange issue with my rear taillights. Brake lights and turn signals work perfect with the head lights off. Turn them on and it seems like I'm not getting enough voltage. The taller of the two filaments on the 1157 bulbs seems to be lighting but real dull. Before I go on a goose hunt tracking the wires back into the cab I'd figured I'd ask see if there is a common problem. Maybe a place I should start?
Thanks
Thanks
I'm going to take a wild guess and assume you mean your brake lights are dim with the headlights ON yet full brightness with the headlights OFF. Am I right? Replace both rear tail light sockets. You have ground shift. 99% of the time, it's due to corrosion within the ground connection of the socket itself.
Replace the sockets; don't worry about the headlight switch.
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Senior User
Joined: Jul 2013
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From: Central Florida
Sorry looks like I didn't explain it very well. I said " The taller of the two filaments on the 1157 bulbs seems to be lighting but real dull."
When the lights are off the longer filament (brakes, blinker) works fine and lights bright but when you turn on the head lights the smaller filament (running lights) seems to be taking all of the power from the taller filament (brakes, blinker) and will hardly light up. So they do work but like they aren't getting enough power. That make more sense?
The sockets look great, no corrosion, could they still be bad?
When the lights are off the longer filament (brakes, blinker) works fine and lights bright but when you turn on the head lights the smaller filament (running lights) seems to be taking all of the power from the taller filament (brakes, blinker) and will hardly light up. So they do work but like they aren't getting enough power. That make more sense?
The sockets look great, no corrosion, could they still be bad?
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
When the lights are off the longer filament (brakes, blinker) works fine and lights bright but when you turn on the head lights the smaller filament (running lights) seems to be taking all of the power from the taller filament (brakes, blinker) and will hardly light up. So they do work but like they aren't getting enough power. That make more sense?
How something "looks" visually is meaningless in terms of electrical conductivity. The only metrics that mean anything here are measurements taken with a multimeter. If you want to be extra cautious, you can ohm out the socket with a multimeter. Of course, there's still the possibility that the sockets are fine, but they are not grounded properly externally. You can verify this as well, but as I alluded to earlier, that scenario typically accounts for only 1% of real cases.
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Senior User
Joined: Jul 2013
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From: Central Florida
Thank you fmc400 I'll check that asap you saved me a ton of time chasing wires. Big help
77&79f250 thanks for the help too. I meant to say the fresh air vent, the one that's by your left ankle and not in the dash itself.
77&79f250 thanks for the help too. I meant to say the fresh air vent, the one that's by your left ankle and not in the dash itself.
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http://www.ebay.com/itm/1973-1979-Ford-Truck-driver-side-fresh-air-vent-/131047653660?pt=Motors_Car_Truck_Parts_Accessories&hash=item1e830c811c&vxp=mtr
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