Constant Battery Drain - Denali
Posted 12 February 2008 - 06:49 PM
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 ?
Posted 12 February 2008 - 07:03 PM
Posted 12 February 2008 - 07:11 PM
Posted 12 February 2008 - 07:13 PM
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 4-¼ 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.
- Wait one minute. Check and record the current reading.
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.
- Note the battery Reserve Capacity, amp hour rating. Refer to Battery Usage .
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:
Posted 12 February 2008 - 08:29 PM
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.
Posted 12 February 2008 - 08:37 PM
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.
Posted 12 February 2008 - 08:50 PM
Posted 12 February 2008 - 08:55 PM
Posted 12 February 2008 - 09:28 PM