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Discussion Starter · #1 ·
2000 AWD Astro
Hey there!
I've been having issues with pulsing lights (both interior and exterior) while the van is running. Sometimes its worse than others. The voltage gauge moves with the pulsing lights, so I recently installed a USB outlet that has voltage reading on it so I could get a real-time number as I drive. It is almost always fluctuating constantly as I drive. Rarely does it sit still, unless the engine is NOT running.
-van off voltage: ~12.4 steady
-van running voltage: ~13.2-15.6 fluctuating
I'm thinking this is pointing towards a faulty voltage regulator of my alternator. I did have O'reilly's check the battery and the alternator; they said both are OK (i don't believe them).

Any thoughts on where to begin with this diagnosis?

Thank you all!
 

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1998 LS AWD Forest Green metallic
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It could be a regulator issue, but they very robust. They usually fail either with no charge, or charging at maximum.

I would begin by thoroughly checking ALL connections in the circuitry between the battery and the alternator, the engine ground cables, and the battery to body ground cables The so-called 'Big Three'. Be sure the alternator is bolted down solidly. ( some even recommend an actual ground strap from the alternator frame to a solid engine or body ground point)
Do a search on 'Big three' and you will find many postings related to that potential 'Big Three' upgrade.
Does the voltage vary more with many accessories turned on ( lights, wipers and heater) , or only with a few ( just normal interior lights, radio, etc) turned on?
Rod J
Issaquah, WA
 

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Discussion Starter · #3 ·
Hey Rod, more loads don't seem to correlate with more variance.

I have been looking into the BIG3 and I think I'll go in that direction from here. I'll see if I can get into that this weekend. Mabye I'll find the culprit along the way.
 

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I suspect doing the Big 3 will fix your problem, being a 22 year old vehicle, pay extra attention to the engine to frame to battery grounds. These are very prone to failure with age.
 

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1998 LS AWD Forest Green metallic
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Several have reported finding a partially broken main output wire from the alternator, often finding broken strands at the lug where it attaches to the alternator.
Rod J
 

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Common Sense + Critical Thinking
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I would check the connections/wires esp down by the starter, tight/clean/corrosion/damage. I'm of the opinion that the 'big 3' is pretty useless for a stock van, but that is just my opinion.
 

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1998 LS AWD Forest Green metallic
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I was referring to the 'Big 3" for reference, as the wires that may be the most likely to be causing the issue. I was not recommending the upgrade for normal use vehicles.
Yes, it is a bit overkill for a stock setup. But it is an option if replacing any of the cables for any other reason.
Now, if you have the 'Big Audio System' and/or the big alternator and auxiliary batteries and a large inverter (needed to run the microwave?) ;), then the 'Big 3' upgrade is definitely worth the effort.
Rod J
Issaquah, WA
 

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Now, if you have the 'Big Audio System' and/or the big alternator and auxiliary batteries and a large inverter (needed to run the microwave?) ;), then the 'Big 3' upgrade is definitely worth the effort.
I agree 100%
 

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Discussion Starter · #9 ·
I seem to have found the culprit. I found that the pos+ lead from the battery at the starter motor wasn't very tight. I pulled the connections, cleaned, and installed properly. Steady voltage while engine is running!

Thanks @AstroWill for the suggestion of the starter connections. I really appreciate that!
 

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Thanks for the detailed reply. Many times we never find out what the specific issue turned out to be. Knowing what you found can be a big help to the next guy with a similar problem.
Rod J
 

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Thanks for the detailed reply. Many times we never find out what the specific issue turned out to be. Knowing what you found can be a big help to the next guy with a similar problem.
100% this, nothing worse than a hit and run.
 
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