what could cause this
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Senior User
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what could cause this
03 6.0 while truck is running the head lights and inter.lights are pulsing are strobing. could this be the alt. going bad are a lose ground ? I've checked every thing I know to . this is driving me crazy
Posting Guru
Joined: Feb 2009
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From: Moyock, NC
Did you load test both batteries the other day concerning your cruise control? Sounds like either 1 or both may be dead and the alt is working overtime...or they're dead because the alt is not performing to standard....perform a voltage drop test on the altenator....also try the magnet on the backside of the alt....see if a screw driver blade of other similar metalic object feels the magnetic attraction while the engine is running. Their shouls be a magnetic pull. Check all grounds and especially both battery termnials...on both batteries, especially the pass side battery. Sounds like you could have an alt going south.
Senior User
Joined: May 2007
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From: Central Texas
Most of the Major auto parts stores will test your batteries and alternator. If you have one close by and the truck is drivable, take it by and have them test both items. Just be aware that continued operation of the truck could cause more damage. If the truck is not operational, its not to hard to remove the batteries or alt.
Fleet Mechanic
Joined: Feb 2008
Posts: 1,955
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From: Eastern PA
I tried to have them test my alternator at Advance Auto Parts, and the guy had no idea what he's doing. Just because it's free doesn't mean it's good. A multimeter and you can do it yourself.
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make sure when you test the batteries to disconnect them. together they will read fine, but apart they will read totally different. i had to learn this the hard way after getting them tested at 5 different places someone finally did it right and had me disconnect one. guess what? they were both shot!
my truck was doing the same thing. after a new alternator, and switching to optima red and yellow tops, it stopped for the most part.
my truck was doing the same thing. after a new alternator, and switching to optima red and yellow tops, it stopped for the most part.
Postmaster
Joined: Jul 2005
Posts: 3,956
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From: Abilene, Texas
I agree have the alt and battery tested and like said it's not too hard to do your self. If it is a battery or alt and you don't get it fixed then you could do some expensive damage like ficm going out.
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DSMMH
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checked batts. this morning with volt metter disconected both of them and was reading 12.53 volts so that looked ok so I reconnected the batts. and started the truck and it ran like crap for a few seconds. put the volt metter on the alt. from the out put on the alt. to the neg. on batt. was reading 13.3 to 4 not shure if that is right. this is an after market alt. 105 amps not shur if that is the right alt. are not had it replaced on the 4th of july
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Posting Guru
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also check the single red wire connected to the pass. side baterry for cleanliness, if it's loose or dirty it'll give you fits, but it sounds to me like the voltage regulator in the alt. is going bad, which is why your'e seeing it "pulse".
FTE Leadership Emeritus
Joined: Aug 2007
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From: Lakewood, Ca.
Take a look at this thread before you run out and buy an alternator:
https://www.ford-trucks.com/forums/8...again-ugh.html
https://www.ford-trucks.com/forums/8...again-ugh.html