Headlights dim at idle
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Senior User
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Headlights dim at idle
So I'm having a problem with my 2003 E150 headlights dimming at an idle after the van has warmed up. If I rev up the engine the lights go back to normal. Also today I went for a hour drive stopped for ten minutes and it wouldn't start. I got a jump start and bought a new battery.
Cross-Country
Joined: Aug 2017
Posts: 51
Likes: 2
From: TN
It could have been a symptom of the failing battery, so check your charging voltage; u can find required voltage on the internet, or Autozone or others will check for free? Also make sure terminals are clean.
Cross-Country
Joined: Aug 2017
Posts: 51
Likes: 2
From: TN
belt maybe loose/ slipping
Lead Driver
Joined: May 2004
Posts: 5,020
Likes: 132
From: Maryville
It is either battery or alternator but I'll go out on a limb and say check your grounds, engine to frame and to battery. BTW I had a fluctuating gauge at WOT, all tests came back inconclusive, I started ignoring it, about a year later the alternator failed, had an internal short, I got it built by a shop nearby, they increased the amperage with better internals.
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Cargo Master
Joined: Apr 2013
Posts: 3,087
Likes: 24
From: Central Florida
A bit of a long shot but have you looked into the DRL module? Or are you describing symptoms that apply when the headlight switch is on?
The DRL module is supposed to turn on your headlights (only, not including parking/marking lights) at reduced brightness.
When mine went bad it caused the headlights to flash similar to a police car.
The DRL module is supposed to turn on your headlights (only, not including parking/marking lights) at reduced brightness.
When mine went bad it caused the headlights to flash similar to a police car.
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Laughing Gas
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Always a good idea to check grounds, but folks, keep it simple. Do the basics first.
Check the charging voltage. It's as simple as putting a meter on the battery while it's idling. You should see about 13.8 volts.
OR, as suggested, go to one of the chains and get it tested. Free, easy, and pretty reliable.
Basics first.
Cargo Master
Joined: Apr 2013
Posts: 3,087
Likes: 24
From: Central Florida
Always a good idea to check grounds, but folks, keep it simple. Do the basics first.
Check the charging voltage. It's as simple as putting a meter on the battery while it's idling. You should see about 13.8 volts.
OR, as suggested, go to one of the chains and get it tested. Free, easy, and pretty reliable.
Basics first.
Check the charging voltage. It's as simple as putting a meter on the battery while it's idling. You should see about 13.8 volts.
OR, as suggested, go to one of the chains and get it tested. Free, easy, and pretty reliable.
Basics first.
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Senior User
Joined: Jun 2006
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What is / where is the diode that you speak of?
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