voltmeter drops to 4 volts

voltmeter drops to 4 volts

Postby webcat [OP] » January 21st 2010, 8:16pm

My 2002 Astro started acting up , i was driving through a parking lot and all the sudden it act like it was going to die , then it would be just fine and then it would do it again , i've noticed that everytime it does it the voltmeter drops to i believe around 4 volts mayby its zero sometimes
It wont start at all now , only cranks , i measured 12 volts at the battery and the headlights come on

The picture is when the key is on engine off
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Re: voltmeter drops to 4 volts

Postby astro355 » January 21st 2010, 8:22pm

What else was the van doing? As causes and effects go, I believe the voltage drop is an effect of another cause. If your engine dies for whatever reason, the voltage reading will drop, the power brakes will fail as well as the power steering. Just curious.
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Re: voltmeter drops to 4 volts

Postby webcat [OP] » January 21st 2010, 8:54pm

astro355 wrote:What else was the van doing? As causes and effects go.


The only thing it ever did was act like it was going to stall or actually stall but it would start back up! I'm thinking it was mainly doing it when i hit the brakes or turned but that may be just a coincidence .

astro355 wrote:If your engine dies for whatever reason, the voltage reading will drop, the power brakes will fail as well as the power steering.

I knew the volts on the voltmeter was supposed to drop if the vehicle died but it should only drop to battery voltage should'nt it or is that what it did and i'm reading the voltmeter wrong , like in the picture i posted , i was thinking that was about 4 volts
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Re: voltmeter drops to 4 volts

Postby astroturf » January 21st 2010, 10:30pm

Your pic says about 11.5 - 12 volts.
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Re: voltmeter drops to 4 volts

Postby webcat [OP] » January 21st 2010, 10:52pm

astroturf wrote:Your pic says about 11.5 - 12 volts.

Ok , thanks , i was reading my voltmeter wrong !!! :dunce:
I know how to fix it from here .
I listened for my fuel pump , nothing
swapped relays , still nothing
i'll check my oil psi switch next and then my fuel pump wires
I want to test my wires right at my fuel pump now.
I'm trying to figure out if my fuel tank has a shield on top like in the second picture down , I guess i'll have to reach up and feel.
Both these pictures are 1999 astros , ones got a shield and the other no shield. :shrug:
My 1996 express van had no shield , very easy !
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Last edited by webcat on January 22nd 2010, 2:38am, edited 2 times in total.
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Re: voltmeter drops to 4 volts

Postby webcat [OP] » January 21st 2010, 10:59pm

astroturf wrote:Your pic says about 11.5 - 12 volts.

Ok , i see were you got 11.5 now , i did'nt see the 9 below the red empty mark , half way inbetween 9 and 14 would be 11.5 :lol:
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Re: voltmeter drops to 4 volts

Postby bobbyjo » February 26th 2010, 2:51am

I also have a problem like yours. But my van doesn't die.
I when it to a store for 20 minutes, came out jump in, turned the key & it turned over really slow as if the battery was flat.
I knew it wasn't. anyway I charge the battery up & still it turns over slowly & will not fire up. checked the link to starting motor.
(this burned out two years ago) it wasn't that. Brought a new battery (store's test says It's bad). Still the same problem.
I'm I missing something? I got a nice spark on plugs! & I Can smell fuel so injectors must be ok. When I put test meter on battery I get 12 volts &also 12 volts
from solenoid, but still only 10 volts showing on the dashboard meter. Any clues?
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Re: voltmeter drops to 4 volts

Postby astroturf » February 26th 2010, 4:30am

bobbyjo wrote:I also have a problem like yours. But my van doesn't die.
I when it to a store for 20 minutes, came out jump in, turned the key & it turned over really slow as if the battery was flat.
I knew it wasn't. anyway I charge the battery up & still it turns over slowly & will not fire up. checked the link to starting motor.
(this burned out two years ago) it wasn't that. Brought a new battery (store's test says It's bad). Still the same problem.
I'm I missing something? I got a nice spark on plugs! & I Can smell fuel so injectors must be ok. When I put test meter on battery I get 12 volts &also 12 volts
from solenoid, but still only 10 volts showing on the dashboard meter. Any clues?


Snap a pic of what you see as 10 volts please. Jim
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Re: voltmeter drops to 4 volts

Postby astro355 » February 26th 2010, 6:20pm

Are the battery connectors clean and free of corrosion?

Did you check the ground connectors?

Was there any maintenance you performed (regardless of what it is) just before this happened?

Do you have any aftermarket electronics?
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Re: voltmeter drops to 4 volts

Postby rev_les » February 26th 2010, 11:33pm

I like the "quick access hole" lol.... I thought it was mine for a second, then realized I never posted a pic when I cut mine out! :rockon:
Anyway, check and make sure all your grounds and the battery terminals are tight.
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Re: voltmeter drops to 4 volts

Postby bobbyjo » February 27th 2010, 4:15pm

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Looking at the other guys photo, my voltage seems higher? if you are saying that he's is between 10-11.5 volts.
So mine must be a normal reading, before starting the van.
I will check ground connections today, where does the negative lead go to from the battery?
There is a thinner wire going to the body near the battery, but the thick one goes down thought the wiring loom?
The red lead goes straight to the solenoid, right?
The link I replaced two years ago was crimped on with a connector, but I'm sure that is good.
Bypassing that with a jump lead straight to the solenoid should turn it over faster.
But it starts to turn over fast, then slower?
Thanks for the feed back so far. :ty:
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Re: voltmeter drops to 4 volts

Postby Astroplane » February 27th 2010, 9:47pm

bobbyjo wrote:where does the negative lead go to from the battery?

Connects to the lowest part of the engine block next to the crankshaft pulley.
bobbyjo wrote:The red lead goes straight to the solenoid, right?

Yes, there is also a jumper or splice from the starter to the alternator with a fusible link between. From the battery, the other positive wire goes to the Underhood Fuse/Relay center.
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Re: voltmeter drops to 4 volts

Postby krautfed » March 1st 2010, 10:07pm

My 2002 just had the same symptoms... luckily right after, not during, a 2 hour one way drive at 1am (for a friend). Later that morning after the trip, on the way to work, the voltage dropped on the instrument panel to 11.5-12v mark with the battery light coming on, then going off (battery light doesn't seem to stay on). I drove it to work and checked connections on the battery, etc. Leaving work, I killed the battery while trying to drive it to the local Autozone and got stranded on the side of the interstate. It died literally 1 mile from my house so I bought new battery and ran strictly off battery to Autozone who confirmed the alternator was not outputing. I immediately drove to my house, took new battery out, and placed it on charger.

I took out the alternator and brought it to a local alternator/starter repair shop (look for the term "armature" in phone books). They confirmed that the alternator was toast. It cost me $60 to have it repaired, not to be confused with rebuilt, as rebuilding involves cleaning, powdercoating, etc and costs $120+ which was more expensive than what a rebuilt exchange would cost ($115). So $60 and 2 days later I put the repaired alternator back in along with that new battery. 100% fixed my problem and voltage gauge now reads 15-16volts (before dieing it read 14volts).

So, this supports the general ideaology that if a voltage gauge reads 12 volts or less while the engine is running... the alternator is not getting the system charged whether its wiring or the alternator itself. Get your alternator checked before it costs you a $80 battery and a tow!
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Re: voltmeter drops to 4 volts

Postby hardlecure » March 28th 2010, 5:44pm

I had that issue with my van once. I replaced the alternator (was the first thing I did on my van actually - big pain that was) and now it's always 14v on the system.
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Re: voltmeter drops to 4 volts

Postby GaryZ » March 28th 2010, 6:10pm

Battery stuff; (connect voltmeter to the battery posts or monitor the dash voltmeter)
1) a good battery will read 12.5Vdc with the engine not running
2) a good charging system will read 14.5Vdc when the engine is running
3) a bad charging system will read the same with or without the engine running
4) a good battery will not drop below 9Vdc when cranking the engine
5) a battery that will not hold a load (bad) will drop below 9Vdc when engine is cranking
6) a bad battery cable connection will turn the starter slow (the bad connection will get HOT)
7) there are two battery cables, check both
8) a bad cable connection can be a loose connection or a dirty connection
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