I have 74 914 which has developed a electrical issue and I am baffled...key out of the ignition the drivers side front and back park light stay on.
key on I pull the headlight switch and the light go on but keep going up and down.
all the light ie signal and brake etc work properly
I have replaced the headlight switch and signal switch but still have the same issue
any ideas?
Full Version: Light Problem Need Help Please
Something is hooked up wrong maybe. At the switch is my first thought
QUOTE
...key out of the ignition the drivers side front and back park light stay on.
Thats normal when the blinker switch is left on......
Or maybe it has a short in the blinker switch?The relay for the head light might need replacing for the headlight that keeps going up and down.
Check all your grounds first. Start near the headlights. Strange things can happen if the circuit sources ground path through the wiring to a "more negative".
DC voltage does not need a true ground to flow current. It only need a "more negative" than the positive source. An example is how the fog lamps work when the low beams are on and not when the high beams are on.
The fog lamp relay sources ground through the high beam lamp filament. When the high beams are on, the "more negative" turns positive and the relay turns off. This is because there is +12V on both sides of the relay coil.
So go out and check all the ground points. Clean and tighten them.
DC voltage does not need a true ground to flow current. It only need a "more negative" than the positive source. An example is how the fog lamps work when the low beams are on and not when the high beams are on.
The fog lamp relay sources ground through the high beam lamp filament. When the high beams are on, the "more negative" turns positive and the relay turns off. This is because there is +12V on both sides of the relay coil.
So go out and check all the ground points. Clean and tighten them.
QUOTE(Mike Bellis @ Mar 17 2015, 07:39 PM) 
Check all your grounds first. Start near the headlights. Strange things can happen if the circuit sources ground path through the wiring to a "more negative".
DC voltage does not need a true ground to flow current. It only need a "more negative" than the positive source. An example is how the fog lamps work when the low beams are on and not when the high beams are on.
The fog lamp relay sources ground through the high beam lamp filament. When the high beams are on, the "more negative" turns positive and the relay turns off. This is because there is +12V on both sides of the relay coil.
So go out and check all the ground points. Clean and tighten them.
ok thanks for the info and I will go over all the grounds....where is the relay for the headlights located?
QUOTE(oxford74 @ Mar 17 2015, 07:56 PM)
QUOTE(Mike Bellis @ Mar 17 2015, 07:39 PM)
Check all your grounds first. Start near the headlights. Strange things can happen if the circuit sources ground path through the wiring to a "more negative".
DC voltage does not need a true ground to flow current. It only need a "more negative" than the positive source. An example is how the fog lamps work when the low beams are on and not when the high beams are on.
The fog lamp relay sources ground through the high beam lamp filament. When the high beams are on, the "more negative" turns positive and the relay turns off. This is because there is +12V on both sides of the relay coil.
So go out and check all the ground points. Clean and tighten them.
ok thanks for the info and I will go over all the grounds....where is the relay for the headlights located?
The motor relays are on the side of the healdight bucket in the frunk (front trunk). The high/low relay is above the fuse panel in the cabin.
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