Flickering lights
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Cargo Master
Joined: Jul 2015
Posts: 3,076
Likes: 21
From: Aransas Pass, Tx
Flickering lights
Hey guys,
When I drive with my head lights on, they strobe from dim to bright, but only when I'm on the gas. At idle, they're always bright. Strobe frequency does not change with rpm. Any ideas what's going on?
1976 f250, 360/390 np435/np205
When I drive with my head lights on, they strobe from dim to bright, but only when I'm on the gas. At idle, they're always bright. Strobe frequency does not change with rpm. Any ideas what's going on?
1976 f250, 360/390 np435/np205
Post Fiend
Joined: Apr 2002
Posts: 19,311
Likes: 97
From: Waterloo, Iowa
Poor grounding at regulator or failed regulator most likely.
http://www.aa1car.com/electrical.htm
http://www.aa1car.com/library/charging_checks.htm
http://www.aa1car.com/electrical.htm
http://www.aa1car.com/library/charging_checks.htm
Post Fiend
Joined: Apr 2002
Posts: 19,311
Likes: 97
From: Waterloo, Iowa
Have battery tested too, not sure if unregulated voltage charging will have toasted a cell? Probably not, something to check, it might. The idea being, want everything on the same page after repairs - a good battery paired with a good alternator. Like Bacon and Eggs.
Spring for fresh grounding cables, to help keep resistance ultra low, where it belongs. Research shows just a few hundredths of a single ohm will cripple an alternator, 30% reduction in output. In fact that may have been what lunched the regulator in the first place.
Spring for fresh grounding cables, to help keep resistance ultra low, where it belongs. Research shows just a few hundredths of a single ohm will cripple an alternator, 30% reduction in output. In fact that may have been what lunched the regulator in the first place.
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Cargo Master
Joined: Jul 2015
Posts: 3,076
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From: Aransas Pass, Tx
Thanks guys. I am going to have to do some research into the 3G alternator. It is always my policy to upgrade when replacing... that's how I got so deep into my powerstroke haha!!
Fleet Owner
Joined: Dec 2009
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From: NorCal
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Cargo Master
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Cargo Master
Joined: Jul 2015
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From: Aransas Pass, Tx
Ok guys.. some not so good news. I just thought my voltage gauge on the dash was bad because it was pegged in the high position after the VR swap. Finally got the multimeter to see if the gauge was correct, and in about 2 minutes of idle, voltage at the battery went from 14.7 to 16.5 V, steadily climbing. I shut it off because I knew something was still wrong and I didn't have the time to play with it.
I really don't want to just get a 3G alternator unless I have to, since this is the budget-fix truck and my powerstroke is the money pit. However, I would still like to be able to drive the old boy, so if I have to get another alternator, I'll bite the bullet.
Any ideas what would cause this? Like I said, steady climbing voltage, no bouncing up or down. Just about 1/10 of a volt every 2 seconds or so.
I really don't want to just get a 3G alternator unless I have to, since this is the budget-fix truck and my powerstroke is the money pit. However, I would still like to be able to drive the old boy, so if I have to get another alternator, I'll bite the bullet.
Any ideas what would cause this? Like I said, steady climbing voltage, no bouncing up or down. Just about 1/10 of a volt every 2 seconds or so.
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Cargo Master
Joined: Jul 2015
Posts: 3,076
Likes: 21
From: Aransas Pass, Tx
My thing is, if I can fix it with a $15 regulator, I don't need to spend the extra $50... Upgrades will come later.
Lead Driver
Joined: Mar 2004
Posts: 8,922
Likes: 153
A bad head light switch can cause that. A bad dimmer switch can too. Reach up in the dash, if the switch is hot it is probably bad.