Driver headlight high beam does not work and my blinkers and flashers will not work with the headlights are on

DUCKY NICHOLS

MEMBER
1998 FORD F-100
4.0L
6 CYL
4WD
MANUAL
26,000 MILES

When I turn on my headlights my blinkers and flashers won't work, but I turn off the headlights the blinkers and flashers start working again. My drivers side high beam doesn't work at all. I changed every bulb on the truck and I checked all the fuses.

1 Reply

JACOBANDNICKOLAS

MECHANIC
109,885 POSTS

Welcome to 2CarPros.

This could be a few things. Honestly, the first thing I would check is for a bad ground. I looked through the schematic and found the headlight in question and signals have a common ground. If it is weak, the added load when you try to run both may cause it to fail. I attached a picture of the wiring I'm referring to. In the pic it indicates where the ground is located. Please keep in mind, a bad headlight switch or multi function switch can be causing this too. However, lets start simple and see where it leads. First, locate the ground and confirm that it is clean and tight, free of damage and corrosion.

Here are a few links for checking electrical you may find helpful:

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

https://www.2carpros.com/articles/how-to-use-a-voltmeter

https://www.2carpros.com/articles/how-to-check-wiring

Take care and let me know what you find.

Joe

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