Pulsating Lights & Volts

Pulsating Lights & Volts

Postby Thunderball [OP] » August 7th 2011, 3:45am

This is kind of a weird problem, but what do you think......

Problem:
I just replaced my alternator with a 1-year reman from Reilly's. About a few weeks later, I noticed that periodically, after starting, my headlights, dash lights, map lights, etc. would 'pulsate' with the engine rpms. They are not going completely off, but they are pulsating like if you were flicking a dimmer switch up and down real quick. I also notice that my volt gauge on the dash reads around 13 volts, not 14.3.

What I've done:
- Replaced the belt tensioner...I thought mine was worn out and causing the belt to slip. Nope, all is good.
- A guy at Reilly's says that I may have a bad voltage sensor??? never heard of it, but says there was a recall for it.
- They tested the alternator and I noticed that the voltage regulator was jumping around a bit, but they said that was normal and appeared fine.
- Battery is a NAPA top of line about a year old. I don't see any battery issues here, good cranking power.

Could I have a bad negative cable ground? All my grounds are clean, but I never did the Negative battery cable to the block connection.
- Where is that connection? I see cable goes down by the power steering pump.

Thanks guys.....
_________________________________________________________________________________
2001 Astro LS - 4.3L V-6 - RWD - 260,000 miles
Original Poster [OP]
User avatar
Thunderball
250k+ Miles
250k+ Miles
Firing on 1 Cylinder (L1)
Firing on 1 Cylinder (L1)
Years of Membership: Thunderball has been a member for 9 full yearsThunderball has been a member for 9 full yearsThunderball has been a member for 9 full yearsThunderball has been a member for 9 full yearsThunderball has been a member for 9 full yearsThunderball has been a member for 9 full yearsThunderball has been a member for 9 full yearsThunderball has been a member for 9 full yearsThunderball has been a member for 9 full years
Posts: 133
Topics: 8
Images: 5
Joined: January 2011
Location: Cleveland, Ohio
Gender: Male
Alias (AKA):
Van Model Year: 2001
Van Make/Model: Chevrolet Astro
Extra Info: LS 4.3L V6 RWD

  • Similar topics
    Replies
    Views
    Author
  • Change overhead spot lights
    by bradaskins » June 15th 2020, 3:20pm in Electrical
    4 Replies
    361 Views
    Last post by Birdshake View the latest post
    June 16th 2020, 3:51am
  • Question about interior "map" lights
    by bradaskins » July 6th 2020, 5:17pm in Electrical
    5 Replies
    312 Views
    Last post by bradaskins View the latest post
    July 7th 2020, 12:25am
  •  
    8
    28
    Last post by AstroSafari.com View the latest post
    December 4th 2020, 8:45am

Re: Pulsating Lights & Volts

Postby 'cudapaul » August 7th 2011, 4:45am

Why did you replace your alternator to begin with?

If you saw the "voltage regulator" jumping around when they "tested" the alternator, hmmm, I think they need to replace it!

BTW, the voltage regulator or "voltage sensor" is INSIDE the alternator, so if it's bad, so is the alternator!
'cudapaul
AstroSafari Pioneer
AstroSafari Pioneer
Firing on 5 Cylinders (L1)
Firing on 5 Cylinders (L1)
Years of Membership: 'cudapaul has been a member for 12 full years'cudapaul has been a member for 12 full years'cudapaul has been a member for 12 full years'cudapaul has been a member for 12 full years'cudapaul has been a member for 12 full years'cudapaul has been a member for 12 full years'cudapaul has been a member for 12 full years'cudapaul has been a member for 12 full years'cudapaul has been a member for 12 full years'cudapaul has been a member for 12 full years'cudapaul has been a member for 12 full years'cudapaul has been a member for 12 full years
Posts: 596
Joined: January 2008
Gender: Male
Alias (AKA): 'cudapaul
Van Make/Model: Chevrolet Astro
Extra Info: LT AWD

Re: Pulsating Lights & Volts

Postby vangogo » August 7th 2011, 6:43am

i agree with paul, have them replace it. Also would be interesting to get a 2nd opinion form a shop other than O'Reallys (sometimes other shops get a laugh out of such things). They kind of pulled a fast one with me when I replaced my alternator last year...i asked if they carried AC delco, they lady said they did not, and tried to sell me a rebuilt one. I explained that I wanted to stick with a new one, and AC delco...she then said, "Oh, we do carry brand new ones", and brought out a box already bagged up. I knew it was not what I asked for, but it was on a Sunday, near 100 degrees and I was on mt mtn bike, so I let her slightly dishonest sales tactics slide (since i did not feel like riding around any more in the heat, with my bad alternator in my backpack). I figured it was an educational experience, and I know not to trust the lady weasle at the local O'Reallys!
PASTAFARI
vangogo
Firing on 1 Cylinder (L1)
Firing on 1 Cylinder (L1)
Years of Membership: vangogo has been a member for 10 full yearsvangogo has been a member for 10 full yearsvangogo has been a member for 10 full yearsvangogo has been a member for 10 full yearsvangogo has been a member for 10 full yearsvangogo has been a member for 10 full yearsvangogo has been a member for 10 full yearsvangogo has been a member for 10 full yearsvangogo has been a member for 10 full yearsvangogo has been a member for 10 full years
Posts: 185
Topics: 11
Images: 3
Joined: July 2010
Location: Oregon
Alias (AKA): VanGoGo
Van Model Year: 1999
Van Make/Model: Chevrolet Astro
Extra Info: LS 4.3 V6 AWD

Re: Pulsating Lights & Volts

Postby Phantom » August 7th 2011, 12:37pm

The battery cable goes down by the starter and bolts to frame , it is possible that your cable is weak , but it is more likely that the problem is the alternator , some companies use a lower quality regulator and they go bad quicker ,,
If bench testing an alternator at a consistent rpm , with no external power drains , it should hold at a steady output reading ,
Normal jumping would be if in a car and you had van in gear foot on brake and having turn signal flashing and or other devices causing a power drain , but in park normal idling it should hold a steady reading .At least 14 volts
Another possible cause with the headlight pulsing is a worn headlamp switch causing excessive resistance and it get hot and shuts off ,,this is common indicator if driving and you turn on brights and the lights either flash or go off , then return to normal when going back to regular dims.
Phantom
Firing on 7 Cylinders (L4)
Firing on 7 Cylinders (L4)
Years of Membership: Phantom has been a member for 10 full yearsPhantom has been a member for 10 full yearsPhantom has been a member for 10 full yearsPhantom has been a member for 10 full yearsPhantom has been a member for 10 full yearsPhantom has been a member for 10 full yearsPhantom has been a member for 10 full yearsPhantom has been a member for 10 full yearsPhantom has been a member for 10 full yearsPhantom has been a member for 10 full years
Posts: 3725
Topics: 15
Joined: July 2010
Alias (AKA):
Van Make/Model: Chevrolet Astro

Re: Pulsating Lights & Volts

Postby Thunderball [OP] » August 8th 2011, 12:32am

I replaced the original at 185,000 miles. It blew the regulator.

Here's what I did today, just to eliminated the possibilities.
- Cleaned all body grounds under the hood. (they weren't too bad)
- Battery connections are all good, just put new connectors on etc and it's nice and clean.
- Checked all connections on the alternator....all good.
- Removed and cleaned the (-) cable connection on the engine block. It looked better than I thought, but cleaned anyway and reconnected.

I'll drive some more and see how it goes. But I do think its an inferior part in the rebuilt alternator. I put a voltage meter on the battery and I get 12.8 volts right out of the battery. When the engine is started, it goes up to, and averages around 13.7 volts.

I'll see how it goes for the next few days. If it keeps up, I'll remove it all together and take it back.

Thanks guys....
_________________________________________________________________________________
2001 Astro LS - 4.3L V-6 - RWD - 260,000 miles
Original Poster [OP]
User avatar
Thunderball
250k+ Miles
250k+ Miles
Firing on 1 Cylinder (L1)
Firing on 1 Cylinder (L1)
Years of Membership: Thunderball has been a member for 9 full yearsThunderball has been a member for 9 full yearsThunderball has been a member for 9 full yearsThunderball has been a member for 9 full yearsThunderball has been a member for 9 full yearsThunderball has been a member for 9 full yearsThunderball has been a member for 9 full yearsThunderball has been a member for 9 full yearsThunderball has been a member for 9 full years
Posts: 133
Topics: 8
Images: 5
Joined: January 2011
Location: Cleveland, Ohio
Gender: Male
Alias (AKA):
Van Model Year: 2001
Van Make/Model: Chevrolet Astro
Extra Info: LS 4.3L V6 RWD

Re: Pulsating Lights & Volts

Postby chevymaher » August 8th 2011, 2:02am

Thats exactly what mine reads to.I got lifetime warrantee so I took first one I changed recently back.Always starts and never does anything wrong.On mine there was a body ground comming out of wiring harness going between fuel pump and engine.Bolted to body near tailshaft of driveshaft toward drivers side.It was nasty cleaned it and radio noise was gone, dome light was brighter.I had a slight resistance testing between body and negative battery.Took 2 days to find it but that was it for that.Another possible culprit is positive power feed that goes through key switch.Connection as it enters through firewall, connection in plug on steering column leading to switch, one in the switch,and back through the same plug comming out before it powers anything.Alot of places to be dirty and gain resistance.I thought my voltage gauge was acting up.Took it out tested it perfect kept hunting.Found bad ground I mentioned.Last but not least gauge not wrong it reading exactly what coming from keyed hot.Anywhere under the hood 13.8 anytime. Anywhere in cab off keyed hot. The more you have turned on the lower that voltage is because of the resistance.Jumped a wire to test problem solved.Same voltage everywhere.Unhooked batt tested yup resistance.And no I never fixed it right now I happy knowing whats wrong.Furds terrible for this exact problem.Just a heads up on other possibilities.
Image
User avatar
chevymaher
Team Leader
Team Leader
Firing on 8 Cylinders (L7)
Firing on 8 Cylinders (L7)
Years of Membership: chevymaher has been a member for 10 full yearschevymaher has been a member for 10 full yearschevymaher has been a member for 10 full yearschevymaher has been a member for 10 full yearschevymaher has been a member for 10 full yearschevymaher has been a member for 10 full yearschevymaher has been a member for 10 full yearschevymaher has been a member for 10 full yearschevymaher has been a member for 10 full yearschevymaher has been a member for 10 full years
Posts: 14210
Topics: 90
Images: 94
Joined: November 2010
Gender: Male
Alias (AKA): chevymaher
Van Model Year: 1994
Van Make/Model: GMC Safari
Extra Info: SLE RWD Mercruiser

Re: Pulsating Lights & Volts

Postby Thunderball [OP] » August 9th 2011, 4:21am

Thanks Chevymaher....I'm going to try and track that ground down too.

All ran good today, no pulsating lights etc. Ran about 275 miles and start/stopped about a dozen times and all starts were good. The only cable I touched yesterday was the main negative ground to the engine block. Took that off, cleaned it and reassembled. Maybe that's all it was. I notice my lights are brighter, especially the interior ones.
_________________________________________________________________________________
2001 Astro LS - 4.3L V-6 - RWD - 260,000 miles
Original Poster [OP]
User avatar
Thunderball
250k+ Miles
250k+ Miles
Firing on 1 Cylinder (L1)
Firing on 1 Cylinder (L1)
Years of Membership: Thunderball has been a member for 9 full yearsThunderball has been a member for 9 full yearsThunderball has been a member for 9 full yearsThunderball has been a member for 9 full yearsThunderball has been a member for 9 full yearsThunderball has been a member for 9 full yearsThunderball has been a member for 9 full yearsThunderball has been a member for 9 full yearsThunderball has been a member for 9 full years
Posts: 133
Topics: 8
Images: 5
Joined: January 2011
Location: Cleveland, Ohio
Gender: Male
Alias (AKA):
Van Model Year: 2001
Van Make/Model: Chevrolet Astro
Extra Info: LS 4.3L V6 RWD

Re: Pulsating Lights & Volts

Postby Thunderball [OP] » August 17th 2011, 4:18am

Those that are following this.....I took the alternator out and returned it to the store for a warranty swap. They bench tested it at the store and the regulator was bad, or should I say it was acting pretty erratic. It would bounce from 13-15 volts as it was charging. Put a new one in and all is good now. Have a constant 14.3v and no pulsating lights. Just a bad part in the rebuilt alternator.
_________________________________________________________________________________
2001 Astro LS - 4.3L V-6 - RWD - 260,000 miles
Original Poster [OP]
User avatar
Thunderball
250k+ Miles
250k+ Miles
Firing on 1 Cylinder (L1)
Firing on 1 Cylinder (L1)
Years of Membership: Thunderball has been a member for 9 full yearsThunderball has been a member for 9 full yearsThunderball has been a member for 9 full yearsThunderball has been a member for 9 full yearsThunderball has been a member for 9 full yearsThunderball has been a member for 9 full yearsThunderball has been a member for 9 full yearsThunderball has been a member for 9 full yearsThunderball has been a member for 9 full years
Posts: 133
Topics: 8
Images: 5
Joined: January 2011
Location: Cleveland, Ohio
Gender: Male
Alias (AKA):
Van Model Year: 2001
Van Make/Model: Chevrolet Astro
Extra Info: LS 4.3L V6 RWD


 
  • Related topics
    Replies
    Views
    Last post

Return to Electrical

It is currently December 4th 2020, 8:45am

Electrical Forum
ElectricalDiscussion specific to electric components of vans. Category for alternators or batteries, starters and ignition parts, anything 12v and electrical issue like fuses, circuitry, wire, terminals, switches, connectors, bulbs, relays, and wiring. Voltage and amperage diagnosis.
To create a new topic in Electrical, click this button:
Previous topic Next topic
Recent Image Attachments
Attached by:
Dbleeger
in Electrical
Views: 184
Comments: 14
Date: Nov 27 '20
Time: 11:29pm
» Read last comment
Attached by:
tungtide
in Electrical
Views: 159
Comments: 10
Date: Nov 23 '20
Time: 4:40pm
» Read last comment
Attached by:
Attached by: stent
stent
in Electrical
Views: 957
Comments: 24
Date: Nov 20 '20
Time: 8:18am
» Read last comment
Attached by:
Attached by: sixsix
sixsix
in Electrical
Views: 313
Comments: 12
Date: Nov 20 '20
Time: 1:16am
» Read last comment
Attached by:
Attached by: AstroWill
AstroWill
in Electrical
Views: 313
Comments: 12
Date: Nov 19 '20
Time: 8:00pm
» Read last comment
Sponsors

Who is online

Users browsing this forum: No registered users and 4 guests