tail light etc circuit ... corrected
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Joined: Feb 2004
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From: The Shenandoah Valley
tail light etc circuit ... corrected
I have long suspected that the brown wire feeding current to the several tail / park / tag / side marker / dash general illumination lights is grounded in or at the headlight5 switch whenever the head light switch is in the totally OFF position. 
I confirmed it today.
I just went out into the 50 degree misting remains of Ian and popped the hood. I have not yet put my fender liners in, so I just twisted the right front marker lamp socket out of the light from behind, then removed the 194 bulb. I used a old neon test light that has a nice 2 foot long grounding wire with clip. I clipped the clip onto my battery's red or positive post clamp, and every time I probed the contacts in that socket ... both for the socket's black ground wire and the socket's brown power wire, the test light came on. Then I inserted it enough that it held onto the brown wire terminal, the light was on, ... and I caused the head light switch to be pulled out for park lights, my test lamp went off indicating it lost ground. The I tried the head light on postion, same result. I turned the HL switch completely off by pushing it all the way back in, my test lamp came back on.
No doubt ... when not used to light the tail lamps, park lamps, marker lamps, tag lights, instrument illumination lamps, etc .... the brown circuit is grounded at / in the headlight switch.
It is by design I'm sure. I am wondering "WHY" it is this way?
Any ideas?
Correction below
My "Bad"!
I confirmed it today.
I just went out into the 50 degree misting remains of Ian and popped the hood. I have not yet put my fender liners in, so I just twisted the right front marker lamp socket out of the light from behind, then removed the 194 bulb. I used a old neon test light that has a nice 2 foot long grounding wire with clip. I clipped the clip onto my battery's red or positive post clamp, and every time I probed the contacts in that socket ... both for the socket's black ground wire and the socket's brown power wire, the test light came on. Then I inserted it enough that it held onto the brown wire terminal, the light was on, ... and I caused the head light switch to be pulled out for park lights, my test lamp went off indicating it lost ground. The I tried the head light on postion, same result. I turned the HL switch completely off by pushing it all the way back in, my test lamp came back on.No doubt ... when not used to light the tail lamps, park lamps, marker lamps, tag lights, instrument illumination lamps, etc .... the brown circuit is grounded at / in the headlight switch.
It is by design I'm sure. I am wondering "WHY" it is this way?
Any ideas?
Correction below
My "Bad"!
Last edited by tbear853; Oct 19, 2025 at 08:20 PM. Reason: Fix it
Cargo Master
Joined: Jul 2005
Posts: 2,313
Likes: 367
From: Kansas
you're misinterpreting your test results...every other bulb on that circuit provides a path to ground from the contact you were probing...you can prove that by unplugging the headlight switch...your test light will still light...
Thread Starter
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Hotshot
Joined: Feb 2004
Posts: 10,846
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From: The Shenandoah Valley
Thank You Sir!
It would have woke up in the middle of the night and I'd have felt a need to sign on just to correct myself. Now I can sleep at ease.
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