Lights not steady
Senior User
Joined: Feb 2007
Posts: 419
Likes: 0
From: TENNESSEE, GO VOLS
there were two different volateg regulators one if equipped with an ammeter the other for a light only , but both are replaced with a single replacement regulator so dont be alarmed if the new ford regulator looks different , i bought mine at napa
you wont be able to find one at a dealer they have long since discontinued them
also see if the ground wire to the body of teh regulator is corroded and a bad rectifier in the alt. will cause the pulsing
if you have a DVOM set it to A/C voltage and probe the battery while its running if you get a reading on A/C scale the recitifier has one or more bad diodes
you wont be able to find one at a dealer they have long since discontinued them
also see if the ground wire to the body of teh regulator is corroded and a bad rectifier in the alt. will cause the pulsing
if you have a DVOM set it to A/C voltage and probe the battery while its running if you get a reading on A/C scale the recitifier has one or more bad diodes
New User
Joined: Jan 2009
Posts: 2
Likes: 0
From: Livermore
Was your pulsating light issue resolved? If so can you shed some light on what it was? My truck has in internal regulator and I have replaced the altenator twice and still have the pulsating lights.. Thanks in advance.
Thread Starter
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Posting Guru
Joined: Jun 2004
Posts: 1,808
Likes: 0
From: Cincinnati Ohio
I never resolved this, after discussing this on the other diesel forums I am a member at, I came to the conclusion it is normal. The pulsating is just the glow plugs from when you first start the truck after it is started they still kick on and off a few times which is normal and they take a lot of juice to turn on and thus takes juice away from every where else. It does it even worse since I switched to the solid state glow plugs. After they do there cycle and all the lights stop flickering.
New User
Joined: Jan 2009
Posts: 2
Likes: 0
From: Livermore
Thanks for the Reply. My Dad has an '89 IDI 7.3 that does the same thing as yours. My 99 does it now after I replaced the altenator except it is the opposite.... They dont start pulsating until 10 or so seconds after I start it up....
Post Fiend
Joined: Oct 2007
Posts: 10,501
Likes: 5
From: Faibanks Ak.
They shouldn't pulse very long after you crank it sometimes that is a sign of a controller going on the blink.
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Post Fiend
Joined: Jan 2000
Posts: 5,330
Likes: 17
From: Dryden, ON, Canada
My 6.9 truck developed pulsating lights not too long after I replaced a dead alternator. I tried another new alt, nothing, I tried a new regulator, and made sure everything was grounded properly, still the same. What it turned out to be was one of the connectors in the regulator plug was loose, replaced the connector, and all is well.
Senior User
Joined: Dec 2005
Posts: 364
Likes: 0
From: Southern Delaware
My truck's lights and voltmeter pulsated for about 18 months...put new VR and it turned out to be a bad diode in the alternator...I put another alt in from a salvage yard and it has cured the many charging probs I had(my voltmeter inthe cab would fluctuate and seem to wag like a dog's tail...weird)...however, the only prob was that the wire conection was 180 degress from where they were on the truck, so I had to take the case apart and rotate the case 180 degrees(which was a pain trying to get the brushes in the holder)....
Junior User
Joined: May 2003
Posts: 51
Likes: 1
From: Eatonville, WA
I had a 91 Explorer that did that. I was told it was the headlight switch. Never replaced it, sold the truck. Pulse would go away when alternator was full fielded. But pulsed constantly at idle.