Head lights flicker - Ranger-Forums - The Ultimate Ford Ranger Resource


Drivetrain Tech General discussion of drivetrain for the Ford Ranger.

Reply
 
LinkBack Thread Tools Search this Thread
  #1  
Old 12-05-2015
Member
Thread Starter
 
Join Date: Dec 2015
Location: Delmont pa
Posts: 6
Head lights flicker

My head lights would flicker while I had them turned on and my brother said my alternator, so I bought another "used one from a salvage yard". It did the same thing but if I hit the gas it stopped. Last night my battery light came on and my battery died. So I put my original alternator back on and it still don't charge. Could it be they both are junk now or is it something else? Please help.
Reply With Quote
  #2  
Old 12-06-2015
RF Veteran
iTrader: (1)
 
Join Date: Jan 2014
Location: Vancouver, BC
Posts: 7,584
You need to get a volt meter to test the system.

key off engine off
Check battery voltage
Lets say it is 12.5volts
(under 12volts means bad battery)
On the back of alternator is a larger Black/Orange stripe wire, it may have a cap on it, remove cap and test for 12.5volts there, if no volts then a Fusible Link is blown.

There will be a 3 wire connector on alternator, unplug it, there will be a Yellow/white stripe wire on this connector, test it for 12.5volts, if no volts then a different fusible link is blown.

If Battery light is working then the green wire is OK

Check white wire that loops back to alternator to make sure wire isn't loose or broken at either end, this wire is not there on some newer alternators, it is internal.

If you have battery voltage at the above 2 wires(Black/orange and Yellow/white) and battery light is working then alternator is bad, period.


Flickering or dimming head lights at idle means at least one of the 3 fields in the alternator has failed, so alternator can't output engine voltage at idle RPMs, if you raise RPMs and lights work fine again that confirms a bad field.

Old alternator could have blown a fusible link when failing, which is why you need to test the wires.

A Fusible Link is a short wire that acts like a "slow blow" fuse, if there is a short the wire will heat up and separate without melting and causing a fire, these are used on alternators because there can be short high amp spikes in voltage that would blow a regular fuse instantly, the Fusible link won't blow just heat up then cool down after the spike.

Last edited by RonD; 12-06-2015 at 11:55 AM.
Reply With Quote
  #3  
Old 12-06-2015
Member
Thread Starter
 
Join Date: Dec 2015
Location: Delmont pa
Posts: 6
Well I just got done testing both wires and they both had voltage in them. One had the same voltage as the battery and the one on the 3 wire plug had 10.5 - 11 volts either because I had key on and not running or not a good connection. Either way both have voltage in them and the wire that loops back to itself is connected from what I can tell. I guess I'll get a new alternator and hope that fixes the issue. Just can't believe both are junk but oh well.
Reply With Quote
  #4  
Old 12-06-2015
RF Veteran
iTrader: (1)
 
Join Date: Jan 2014
Location: Vancouver, BC
Posts: 7,584
Salvage yard alternator should have warranty, I just got one a few days ago with 60 day warranty, it did work fine, but not when first installed.
The old alternator blew the 15amp Yellow/white wire's fuse, in 1994 models Ford used fuses not fusible links.
So when I started the engine with new(used) alternator installed I still had the Battery Light on.
Had 0 volts on Yellow/white wire so checked the fuse and it was blown, installed new fuse and charging system was working again :)

The Yellow/white wire is hooked directly to the battery's "+" cable, so should have same voltage as battery, you could have corroded connector.

Your battery's "+" terminal should have 2 wires coming off it, larger wire goes to starter motor, smaller wire to Battery Junction Box, the battery junction box is where both the wires you tested connect, so both should have the same voltage, battery voltage.
You may have had a bad connection or poor ground on meter, but I would retest to make sure.

Last edited by RonD; 12-06-2015 at 07:15 PM.
Reply With Quote
  #5  
Old 12-06-2015
Member
Thread Starter
 
Join Date: Dec 2015
Location: Delmont pa
Posts: 6
I had my key in the on position so could that be why there was a difference in the voltage? I didn't have it running just the key turned on.
Reply With Quote
  #6  
Old 12-06-2015
Member
Thread Starter
 
Join Date: Dec 2015
Location: Delmont pa
Posts: 6
I checked the voltage again and it was the same in both wires and checked the wire that loops to the plug by itself and couldn't find any breaks in it anywhere at all. My only option is to go by a new one and put it on and hopefully it is the problem.
Reply With Quote
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Headlights flicker while driving Guth16 General Technical & Electrical 2 09-17-2013 12:37 PM
2001 Ranger Oil Gauge Flicker, Very rattly engine. adams0421 General Ford Ranger Discussion 11 11-16-2011 09:07 PM
Lights flicker. Any suggestions? rotekk General Technical & Electrical 3 09-22-2010 07:47 PM
My headlights flicker...Help! dross93ranger General Technical & Electrical 7 06-28-2008 09:34 AM
Blown head gasket or cracked head rangeon99 4.0L OHV & SOHC V6 Tech 20 12-04-2005 02:36 PM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -6. The time now is 05:01 PM.


We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.