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Constant Battery Drain - Denali


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#1 KVacek

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Posted 12 February 2008 - 06:49 PM

Our "new" 2005 Yukon XL Denali just refused to start while my wife was at the gas station. I got there and tried it and it only clicked - a quick jump and everything's running fine. Charging well, battery healthy, but there's a constant 3.6-amp drain on the battery.

It's cold and dark and snowing - I'd like to narrow it down a little before pulling all 3 zillion fuses to check. No lights are on, nothing's obviously running. Anything a likely culprit to check first, before I just test everything one by one ? And if it's not a fused circuit, is there an easy way to disconnect and check the alternator for a bad (stuck) regulator, without pulling off the plastic cover over the engine ?

Also - do the Omron breakers plug in ? That is, can I pull them out to check whether any of their circuits are causing the drain, or are they soldered in ?

Thanks!
Karl

#2 Silverado-CoA

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Posted 12 February 2008 - 07:01 PM

did u wait 20min after powering off to do the draw test? takes that long for the ecu,s to power down.

#3 KVacek

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Posted 12 February 2008 - 07:03 PM

Nope. I just pulled off the negative terminal and threw my Fluke on it. Is there a recommended procedure ?

Thanks!
Karl

#4 ryanawesome

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Posted 12 February 2008 - 07:11 PM

snap the hood latch shut. Put the fluke on the negative terminal set to the highest amperage. Lock the truck and wait about 30 minutes. Let all the modules power down and then check for draw. A general spec for draw is 30-40 mA.

#5 Silverado-CoA

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Posted 12 February 2008 - 07:13 PM

Vehicle may have a concern with the battery going dead overnight. The draw can be from 40 to 60 mA. This is due to the HVAC control head staying "awake". Further diagnostics may show that the draw is reduced to approx 5 - 9 mA with either the front HVAC controller unplugged or HVAC fuse B pulled. Disconnecting (& reconnecting) the battery may result in the draw being gone until the next key cycle. The rear HVAC head is unrelated to this issue.

<A href="http://service.gm.co...m#ss2-1910798">
Recommendation/Instructions:
A draw of approx. 60 mA for 2.5 to 3 hours after vehicle shutdown is normal. The time varies with ambient temperature. However, this should NOT be enough to drain the battery.

DO NOT replace the HVAC control head for a draw of 60 mA (approx) or less.



When diagnosing battery draws on trucks equipped with the automatic dual zone HVAC controls (RPO CJ2), technicians should keep in mind that the control head does not completely "go to sleep" until after 150-250 minutes, or up to 4- hours, from when the ignition key is turned OFF. This is a normal condition. In these cases, DO NOT replace the control head.




saw these for ur truck. duno if theyll help but heres how we do it:
  • <LI type=1>Disconnect the battery negative cable. Refer to Battery Negative Cable Disconnection and Connection . <LI type=1>Install the male end of the J 38758 to the battery ground terminal. <LI type=1>Turn the J 38758 test switch to the OFF position. <LI type=1>Install the battery negative cable to the female end of the J 38758 . <LI type=1>Turn the J 38758 test switch to the ON position. <LI type=1>Road test the vehicle and activate ALL of the accessories, including the radio and air conditioning. This may take up to 30 minutes. Important: Leaving the key in the ignition on some vehicles may cause a parasitic drain that is above the recommended amount. Refer to Body Control System Description and Operation .

    <LI type=1>Park the vehicle. Turn the ignition switch to the OFF position and remove the ignition switch key. <LI type=1>Connect a 10-amp fused jumper wire to the test switch tool terminals. <LI type=1>Turn the J 38758 test switch to the OFF position. The current now flows through the jumper wire. <LI type=1>Wait one minute. If the fuse blows, install an inductive ammeter to locate the current draw. <LI type=1>Turn the test switch to ON and then remove the fused jumper wire. <LI type=1>Set a digital multimeter to the 10 A scale. <LI type=1>Connect the digital multimeter to the test switch tool terminals.
  • Turn the J 38758 test switch to the OFF position. The current flows now through the digital multimeter.
<LI type=1>
  • Wait one minute. Check and record the current reading.

  • 15.1.
When there is a current reading on 2 A or less, turn the J 38758 test switch to the ON position. The electrical current will now pass through the switch.

15.2. Then switch the digital multimeter down to the 2 A scale for a more accurate reading when the J 38758 test switch is turned OFF.

  • <LI type=1>Turn the J 38758 test switch to the OFF position. Wait 15 minutes for most vehicles.
  • Check and record the current reading.
<LI type=1>
  • Note the battery Reserve Capacity, amp hour rating. Refer to Battery Usage .

  • 18.1.
Divide the reserve capacity by 4, amp hour rating by 2.4.

18.2. Compare this to the multimeter milliamp reading taken in the previous step. The parasitic current drain should not exceed this number. Example: If a battery has a reserve capacity of 100 minutes, (60 A/H) the current drain should not exceed 25 mA.

<LI type=1>
  • If excessive current drain is not found at this time and there are no other apparent causes, complete the following:

  • 19.1.
Using the MIN/MAX function of the digital multimeter, monitor the parasitic drain overnight or during the day. This will determine if something has been activated during that time frame



#6 KVacek

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Posted 12 February 2008 - 08:29 PM

Well, after 30 minutes it's at 8 ma. I put it on min/max and will check later or in the morning.

However, I DID NOT have any way to duplicate the full test, as I didn't rig up a jumper cable to enable running the vehicle and then switching it to the meter - I just disconnected the negative battery cable and put my Fluke between the cable and the battery, closed the hood and locked the vehicle.

Is that good enough, or is there something more to be found by doing the whole test with a switched jumper so I can keep the battery constantly connected? It sounds like the HVAC head will not be "on" if the battery is disconnected and reconnected unless there's another "key on" cycle. My Fluke only takes 10 A, so I'd have to make a heavy switched jumper like the real GM tool.

#7 ZZ327

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Posted 12 February 2008 - 08:37 PM

You might be over analyzing this, maybe you just need a new battery? Yours might have a bad cell in it. Have your auto parts store or shop do a battery load test.



Try charging up your battery and disconnecting the leads overnight, and reconnect in the morning to see if its still charged

Edited by ZZ327, 12 February 2008 - 08:48 PM.


#8 ryanawesome

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Posted 12 February 2008 - 08:50 PM

I agree. Check your battery. A weak or dead cell will draw voltage from all the other good cells slowly draining the battery.

#9 KVacek

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Posted 12 February 2008 - 08:55 PM

Could be, but I initially rejected a bad battery because the resting voltage is a bit over 13. Even an old, solid battery usually measures lower and yet still cranks OK. This really seemed more like a bad battery cable connection, but the connections are clean and they were reasonably tight when I removed them to check. Might be an intermittent shorted cell though.

Thanks!
Karl

#10 MS03 2500

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Posted 12 February 2008 - 09:28 PM

The only way to test a battery is a load test, that 12 volt means nothing