RE: Where & How to test & locate Parasitic drain-2000 Chev Express?

Discussion in 'Automotive Electronics' started by 1.5 v bat, Mar 7, 2016.

  1. 1.5 v bat

    Thread Starter Member

    Mar 6, 2016
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    I read that disconnecting the wire on the alternator overnight and check battery level in the morning. But I did not say which battery wire. I Believe they meant the Large Red Output Wire. Usually there is another plastic connector with 2 more wires. I can't seem to access the rear of the alternator. I'll take the cowl cover off inside the van. Supposedly It may have a bad diode inside the alternator. My alternator charges, but I've been disconnecting my battery cable every time when I'm done using the van. A mechanic told me to turn on headlights, wipers, heater fan, & step on the brake lights while watch the if the voltage gauge drops from 14 volts. It did not drop. I was reading on You Tube this morning ADP Training/ Build your own test equipment and the narrator mentioned that Body Control Modules, ABS, SRS, and
    other sub system modules can cause parasitic drain. And ADP shows how you can build a diagnostic tool from electronic components called a Fuse Voltage Drop Short Identifier together with a Voltage to Amperage chart they've developed in 2012. They say to try using a DMM first because their meter is sensitive. And to Test across System fuses
    while the fuses are installed in the vehicle. - I know its sounds like I answered my own question here but I always need a game plan on where to start poking around. Electricity was never my forte I graduated Electrical Construction and Maintenance at my local community college. Let me know if you have any new angles. Thank you ! : )
     
  2. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    Voltage tells you nothing is this case. None of the electric loads are heavy enough to cause a noticeable voltage drop.

    You need to monitor current. You need to connect an ammeter on the 12 volt line leaving the battery. Pull all your fuses. You should not see any current draw. Put the fuses back in one by one at which point you will discover which circuit is pulling current with the ignition off.
     
    JWHassler and #12 like this.
  3. #12

    Expert

    Nov 30, 2010
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    It's a lot easier with a helper. You watch the meter, he takes the fuses out and then puts them back...one at a time!
    I found the problem in a Chevy Astrovan in 35 minutes. It had been to a Goodyear repair shop 4 times, and they never measured for leakage current. They just replaced the alternator and battery 4 times.:confused: WTF? The customer bought a thousand dollars worth of incompetence?:mad:
     
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  4. 1.5 v bat

    Thread Starter Member

    Mar 6, 2016
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    That's what I'm talkin bout! Thanks a real LOT KERMIT ! and # 12 AAC Fanatic! Right on ! : )
    I Love you guys!
     
    Last edited by a moderator: Mar 7, 2016
  5. KeepItSimpleStupid

    Well-Known Member

    Mar 4, 2014
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    Looking at voltage is not strictly true. See this article: http://www.autonerdz.com/yabbfiles/Attachments/HowtodoParasiticdraintestacrossfuses.pdf

    The fuse has two test points, and the table gives you an idea what the current in that circuit is based on the small voltage measured across the fuse. It's a place to start.

    Problem is, the car has lots of fuse boxes.

    You have to watch on some cars, it takes a while for the systems to power down after the car is turned off.

    I would look at the dome circuit first.

    The alternator is also a tough one to diagnose. The big fat wire to the alternator to the battery would remove the diodes in the alternator "leaking".

    The starter would be a tough diagnosis too.

    And yes, it could be a body control module. It could be the radio. The Hazard switch.

    If the drain is substantial, you may be able to look at the voltage drop across the battery to ground wire.

    Just remember, it might take 20 minutes for the car to shut down. Stay away from orange wires. I believe that's the universal color of the airbag system. It's also recommended that after turning off the car, don't do anything electrical for about 5 minutes. Enough time for the air bag system to shut down.

    One question, I have for you is just how long does it take to get the battery flat? You have already answered that removing the battery cable fixes it.
     
  6. 1.5 v bat

    Thread Starter Member

    Mar 6, 2016
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  7. 1.5 v bat

    Thread Starter Member

    Mar 6, 2016
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    Hey, Thanks KISS, Thank you for your detail. I love attention to the details! : )
    - It goes flat in one overnight. - figure 12 hours.
     
  8. 1.5 v bat

    Thread Starter Member

    Mar 6, 2016
    37
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    Hey kiss! I Also thank you for the mV / fuse amperage chart Link. Thank you So Much! ! !
     
  9. KeepItSimpleStupid

    Well-Known Member

    Mar 4, 2014
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    You have serious draw or a really bad battery.

    Do me a favor and rule out the battery by using a battery hydrometer. e.g. http://www.amazon.com/E-Z-Red-SP101-Battery-Hydrometer/dp/B000JFHMRU It's not likely based on what you said, but it's worthwhile.

    Take a look at the wire(s) leading away from the battery. If you can access both ends, TRY to measure the voltage across the wire and start there.

    If you have a wiring diagram of the car, all the better. There may be fusable links you can access too.

    If you have the wiring diagram things become more systematic.

    Just remember there are more than one block. In one car you had to remove the right kickpanel with a screwdriver. There are fusable links which could be a "wire in the fusebox".

    I'd go after dome, Radio, Park ECM, BCM, PCM first.

    Remember to force the dome circuit OFF with the switch. Don't rely on the fuse. Some circuits involving the alternator like a leaky diode will be hard to spot.

    If you find a big draw, it may be best not to pull fuses willy nilly. If your good, you can disconnect the battery. Remove half the fuses. See if the problem goes away. Remove the other half. Now binary search the fuses.

    If If you remove all of the fuses in the interior panel and it has not gone away. It's not there. If you install half and test and the problem is not there, then it's likely in the other half. Keep diving the number of fuses by 2.

    The glove compartment lamp switch is another hidden gem.

    Other options exist, like putting a resistor between the battery cable that could handle 29 ams and not drop a lot of voltage (Say 1V).
    Put a fuse, resistor and connect in series with the battery cable. e.g. http://www.digikey.com/product-deta...amp-connectors/9-1625984-2/A102179-ND/2056130 0.1 ohm 50 W.

    These https://www.pololu.com/search?query=current+sensor&x=0&y=0 sensors could increase your sensitivity, but you need a 5V supply. A USB wall wart would work. Agian, fuse at the maximum.

    These are just some low-cost ideas.

    Yea - attention to detail. That;s what my psyc profile says.
     
  10. bwilliams60

    Active Member

    Nov 18, 2012
    725
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    First off, you are looking for a current draw greater than 30mA and the best tool is a good inductive ammeter placed around either the positive or negative battery cable. Make sure you include all cables coming off that post. Second choice is an inline ammeter placed between the negative battery cable and the ground post. Some will say to use a test light but this is not a valid test.Once you are connected, make sure the key is turned off and all accessories are turned off. Because of control modules, you must now allow the car to go to "sleep". This allows all modules to power down, do their housekeeping and get ready for the next startup. Depending pn the vehicle, this could take up to an hour but most will be done in about 20 minutes. Check the amperage draw now.If it exceeds 30-50mA, you have a problem. Start pulling fuses one by one as #12 said, until the draw goes below spec. If there is no change when you pull one, put it back in. If it drops but not below spec, leave that one out and continue pulling until below spec. Sometimes more than one circuit could be affected. If you pull all and still nothing, look to the alternator or any other device connected directly to the battery such as add-ons. Generally the alternator will draw 2 - 4 amps because it is the regulator and rotor that stay turned on.
    Once you have found the fuse and circuit causing the problem, you will need a wiring diagram. Take the circuit and start disconnecting it as you work your way from negative to positive. At some point, the draw will disappear. You have now found your problem area. Usually a component. Don't jump around looking at dome lamps etc, follow the procedure, much faster. Good luck.
     
  11. shortbus

    AAC Fanatic!

    Sep 30, 2009
    4,019
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    My one son has a van like this too(1999Chevy express). His would drain the battery over the weekend, when it wasn't driven. Ended up it was the under hood light not turning off when the hood was closed. Took out the bulb, now battery stays charged.
     
  12. 1.5 v bat

    Thread Starter Member

    Mar 6, 2016
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  13. 1.5 v bat

    Thread Starter Member

    Mar 6, 2016
    37
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    Thanks for that ShortBus! I forgot all about that My hood lite does not work at all but a mechanic said to take the bulb out any way and to check mercury actuated switches. I' gonna go check that right now! Thank You Short Bus !
     
  14. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    It may not be the fix for you, but was for my son. Those lights are also in some car trunks. They aren't mounted real secure and can get bent or moved so they are then on all the time. I got tired of going to his house on Monday mornings to give him a jump start.
     
  15. 1.5 v bat

    Thread Starter Member

    Mar 6, 2016
    37
    1
    Update : There is no underhood lamp on this stripped down model.
    Took it for a drive. Left it running when I got back. Ran in the house got my clamp-On D.C. am-meter.
    The pos side terminal style cable head has the main #6AWG running down to the starter solenoid.
    And the #10 Red to the alternator. And another #10 Red runs across the fan cowl to port-side and dis-appear under the air filter box in the area near the MAF sensor and relays/fuse box. (I'll have to remove air box to see exactly). - Anyway my Craftsman Clamp Meter does not have mA function setting. It Has (2) forty amp positions and the one was reading 16. amps w/o being connected to anything. So I clicked it around to the other 40 amp
    position setting and it zeroed out like I wanted to. Then I took readings on the smaller two #10AWG wires and the alternator wire read 2-3 amps output. The other #10AWG read about the same and the large #6 battery cable read .0009 Amp (10 thousanths of an amp). Anyway it looks like I am going to change out the alternator. But that's not going to get my Digital LED Clock/Radio to work again I bet. In the old days I would have already thrown money at it and purchased an alternator immediately. But now I tend to take my time and test around. Let me Know about that Digital LED Clock/Radio Symptom (It hasn't work since the new ignition switch was installed). Thanks Guys and Gal's?
     
  16. 1.5 v bat

    Thread Starter Member

    Mar 6, 2016
    37
    1
    Another Update for Today! - I Installed a new alternator. I performed the same tests with same DMM and Clamp On Amp meters on the new alternator to confirm. And I got the same numbers as this morning. I'm not sure about how that Sears Craftsman Clamp On's; Amperage Selections are. At first it looks redundant because it has (2) 40A selections where one will read zero; Before connecting, and one will read 16. 57
    it has (2) 400A selections where one will read zero before connecting and one will read 16.57 before connecting. Those are the only four choices for it's amperage selections. The readings that make the most sense are taken when the selection starts at the 16.57 before clamping around the wire because it then reads almost 40A while idling probably around 700 RPM. < - - - (The Selector being set for 400A).
    I had not used the 400 amp selection earlier this morning. The numbers were all the same but the decimal was in the wrong place. Which was confirmed; -What I thought was 3A on the 40A setting is 39A on the 400A setting. So it looks as there is no change between old alternator & new alternator. However there is change.
    The Dash Gauge which is a Volt Meter increased from 14 to 16. And the van starts-up faster and idles smoother. The real test will be overnight. This will be the first night in a long time that I am leaving the battery connected overnight. The Harbor Freight Digital Multi-Meter is still reading .1A draw with key off. The only thing I know of that will be drawing current tonight is that the gear selections indicator stays lit all the time. My Digital LED Clock did not come to life. I think back when I replaced the Ignition switch and transponder, I killed the clock and radio somehow.
     
  17. 1.5 v bat

    Thread Starter Member

    Mar 6, 2016
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    One Last update for today : I made a misprint in that last blog. It was not .1Amp
    (one-tenth of an amp).
    It was one whole Amp draw with key in the off position.
    That would be 1000 milliamps draw with the key in the off position. I also measured the battery voltage being 12.53 volts after idiing maybe 10 ten minutes total on the new alternator. We'll see if it discharges by tomorrow morning.
     
  18. bwilliams60

    Active Member

    Nov 18, 2012
    725
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    Do I understand you correctly? Do you have 12.53 volts with the engine running. If so, do yourself a favor and shut it down and put the battery on a charger for a few hours. An alternator is not a battery charger and my guess is it will be hot enough to cook your dinner on in no time.
    As for the other, if you follow exactly what I said and you get accurate readings on your current draw, I can tell you what to do next. When we figure this out we can look at your other problems but for now, lets get current draw solved. Stay on course. Pulling bulbs and other things are guesses.
     
    Last edited: Mar 10, 2016
  19. GopherT

    AAC Fanatic!

    Nov 23, 2012
    6,073
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    Check the electrolyte level in your battery. Regular cells are coming back - not everything is completely maintenance free as it seemed 10 years ago.
     
  20. KeepItSimpleStupid

    Well-Known Member

    Mar 4, 2014
    1,150
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    For inductive to work, the current must be time varying, The DC/AC clamp-on technique resorts to hall effect.

    -1 or +1 may be the meter's way of indicating an overload. The ohmmeter function might indicate +1 (no decimals) when the leads are open.
    The ammeter mode with nothing connected will indicate 0. if it;s over range, the motor might indicate +1 or -1 with no decimals.
    Usually only the high current range is fused.
    [/quote]


    But your meter works on "conventional current" where positive is the convention positive to neg. It matters in solid state physics and tube curcuits somewhat (electron beam deflection) and solid state physics, so it mattered to me in my lifetime.

    You won't have 0. A few mA is permissible

    Fixing your clock.

    I MAY be able ell you an easy fix. On a vehicle I had the clock died shortly after i jumped my car. The "trick" worked and there is a scientific basis as to why it works. I've fixed someone elses HP calculator, a bike computer (It slid across a carpet) and my own automotive clock.

    When the battery drain is fixed, I'll reveal the method. No distractions for now.

    Make sure no codes are being thrown. The radio/ignition might not have been programmed to the BCM.

    I had a 2000 Chevy BCM replaced and the tire pressure monitor and interior lighting didn't work after replacement, I can't remember what happened, but the "new" BCM was replaced.

    16V seems too high an alternator output.
     
    Last edited: Mar 10, 2016
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