Skip the auto shop - Our mechanics make house calls

Q: When headlights are on, turn signals do not work - 1979 Ford F-100

asked by on

When my truck's headlights are on, the right turn signal does not work and the tail lights go from bright to dim. The truck can be running while it is just sitting parked and the same problems occur with the headlights, turn signals and tail lights. I have changed the bulbs but the problem still exists. What do you suggest that I do to fix this?

If the items share a common ground or power circuit, there could be a loose connection or a bit of corrosion in the shared circuits in the steering column. The cross contact from corrosion growing across circuits can cause similar symptoms. If you would like, a certified technician from YourMechanic can come to your home or office and inspect your electrical wiring.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!
  1. Home
  2. Questions
  3. When headlights are on, turn signals do not work - 1979 Ford F-100

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Will a supercharger blow my motor?

Hello There! A supercharger can be a great horsepower addition, however some things to keep in mind are things like fuel octane requirements, cooling issues and fueling and timing corrections. As you know, when adding a supercharger, you are creating...

Q: Sluggish feel in gas pedal

Hi there, thanks for writing about your 1979 Volvo 244. First, you should confirm there is good spark at the spark plugs to eliminate ignition as a problem. Then, check fuel pressure for the correct pressure - it is likely...

Q: Turn signal issues on a 2000 Ranger

It could be. The emergency flashers and the turn signal flashers use different flasher relays in them. They are a separate thing. You'd want to pray it is just the flasher because if it isn't the flasher, then it is...

Related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.