No power to headlight switch

Tiny
ERICH PETERSON
  • MEMBER
  • 1993 FORD E-SERIES VAN
  • 5.8L
  • V8
  • 2WD
  • AUTOMATIC
  • 89,000 MILES
Hi,

My running lights and dash lights do not work. I have found that the fuse controlling those functions at the power distribution box doesn't have 12v on either side of the fuse, which supplies power to the functions that are not working (tan/white wire).

I'm wondering what I should do now. Pull the distribution box and look at wiring inside? If so, I'm not seeing how to get into it.

Thanks
Thursday, October 21st, 2021 AT 3:08 PM

12 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Hi,

Is the fuse you checked in the vehicle or under the hood? There is a 60-amp fuse under the hood that sends power to the headlamp switch. Also, there is a 15-amp fuse in the vehicle.

Looking at the wiring schematic, the wire coming from the fuse is a black wire with an orange tracer. See schematic below.

Let me know if that is what you checked.

Joe
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Thursday, October 21st, 2021 AT 9:23 PM
Tiny
ERICH PETERSON
  • MEMBER
  • 34 POSTS
Hi,

It is the fuse (10 amp I believe) under the hood that is marked in the owner's manual as being for "running lights". The tan wire with the white tracer I reference is the wire that goes into the back of actual headlight switch. I read somewhere that that wire goes straight to the fuse box, to that fuse location. So, I tested for voltage on that fuse, and get nothing. PS-headlights work fine.
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Friday, October 22nd, 2021 AT 5:42 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Hi,

Thanks for the update. I'm glad to hear they are working for you again. Driving in the dark is a bit of a challenge and dangerous without taillights. LOL

Regardless, I'm happy to hear it is working. Please feel free to come back anytime in the future if you have questions. You're always welcome here.

Take care of yourself,

Joe
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Friday, October 22nd, 2021 AT 7:16 PM
Tiny
ERICH PETERSON
  • MEMBER
  • 34 POSTS
Oh, sorry, if I implied it was fixed. The headlights work, but the parking lights and the dash lights do not work. I think these two functions are fed by the tan and white wire in the harness, which doesn't seem to have power on either side of the fuse under the hood at the fuse labeled running lights.
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Saturday, October 23rd, 2021 AT 6:28 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Hi,

No problem. I thought it was working. Let's get this figured out.

If you look at pic 1 below, it shows fuse 4. The wiring starts dark blue with an orange tracer, and then there is a splice into the tan/white wire you checked.

Since there is a splice, I need to confirm there is no power to fuse 4 in the instrument panel fuse box. If there isn't, check fuses 8, 12, or 16 to see if they have power. If they don't, go to the fuse box under the hood. Locate fuse S and check it for condition and power to and from it. (See pic 2 for location).

Now, if fuse 4 in the vehicle has power but you don't have power at the tan/white wire, then the splice is likely the cause.

Let me know what you find. Also, because if the model year, my schematics are limited. I'm providing OEM schematics and they are not as easy to follow as others. LOL

Take care,

Joe

See pics below.
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Saturday, October 23rd, 2021 AT 7:00 PM
Tiny
ERICH PETERSON
  • MEMBER
  • 34 POSTS
Thanks, I checked fuse 4 and it was fried. Replaced it and now the parking and ash lights work.
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Tuesday, October 26th, 2021 AT 3:31 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Erich,

Great! I'm glad to hear you got them working.

Please feel free to come back anytime in the future if you have questions or need help. You're always welcome here.

Take care,

Joe
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Tuesday, October 26th, 2021 AT 5:35 PM
Tiny
ERICH PETERSON
  • MEMBER
  • 34 POSTS
Hi again,
So the fuse #4 is continuing to blow when switching to park and/or headlights, and I am at my wits' end trying to find the short.

Here is what I have done thus far:
1. Placed a new 20A fuse in.
2. Disconnected the headlight switch.
3. Placed a 2.75A test lamp across the T/W and BR pins on the headlight switch connector. This illuminates the test lamp (indicating a short on the highlighed portion of the attached wiring diagram).
4. I have unplugged every light and module in the second attached diagram, but the lamp remains on.
5. I think I have located the connector labeled/highlighted as #1 in the second attached diagram and have disconnected it (the lamp still stays on).

I'm wondering if someone can take me step-by-step on what to test. In particular, where to find each of the connectors! PS - this is a conversion van.

Thanks so much.
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Tuesday, September 2nd, 2025 AT 12:23 PM
Tiny
ERICH PETERSON
  • MEMBER
  • 34 POSTS
UPDATE #1: OK, so I finally found the connector just beyond the anti-theft module in the B-pillar behind the driver. I disconnected it, and the test lamp went out. I will now attempt to find the short between it and the tail lights. Do not need any help at this time. Will update if I finally find the short.
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Wednesday, September 3rd, 2025 AT 7:04 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,137 POSTS
If the van has trailer wiring I would go there first, also, remove all running light bulbs and check to see if the light sockets are melted or rusted. This guide should help.

https://www.2carpros.com/articles/no-tail-lights-exterior-running-lights-tail-lights-out

Please go over this guide and get back to us.
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Thursday, September 4th, 2025 AT 10:07 AM
Tiny
ERICH PETERSON
  • MEMBER
  • 34 POSTS
UPDATE #2: SOLVED.
I finally found the short. It was between the license plate light connector behind the left rear tail light and the light itself. It was intermittent when opening and closing the rear door, which made it seem several times like it had been fixed. Thanks for the help.
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Monday, September 8th, 2025 AT 9:11 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,137 POSTS
Nice! Glad you could get it fixed, thanks for letting us know. Please use 2CarPros anytime we are here to help.
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Monday, September 8th, 2025 AT 11:15 AM

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