Battery draws down after 24 hours

[The_Family_Tahoe]

1999 Tahoe
Battery is drawn down low enough it won't crank after about 24 hours.
I disconnected the negative cable and put my voltmeter on 10mA and bridged between the negative post and negative cable. The reading is .014. What is a normal measurement reading for this truck?
I tried removing the underhood fuses one at a time to see if the reading would change but it never did. It always reads .014.
All recommendations and suggestions are greatly appreciated.
Thanks

 

[GoToGuy]

What about the fuses on left side of dash?

 

[Wildblue19]

A typical car battery is around 50 amp hours, so at that low of a draw it should take months for the battery to drain to a point to where it wouldn't crank. Is the battery known to be good? Can you test with another battery? Also, the measurement not changing with fuses pulled is suspect - you would expect to see the quiescent draw decrease with the fuses pulled.

 

[GoToGuy]

There are some utube vids that are good, it would easier and quicker than trying to explain a few different ways to narrow it down.

 

[Schurkey]

The alternator diode(s) could have shorted; that would not be affected by the fuses.

However, I'd also expect higher amperage draw. I don't worry about parasitic drains under about 0.2 amps. I'm not sure of your meter reading--you're saying you have a drain of .014 mA? Or .014 A?

Are you sure the battery is not self-discharging via the conductive slime that builds-up on the case? CLEAN the battery case.

Disconnect both battery cables, FULLY charge the battery so that it has 12.6--12.7 volts AFTER it's been off the charger for an hour. (It'll maybe have 13+ volts when fully charged and fresh off the charger.) See what happens.

The battery may be plain ol' defective, unable to hold a charge.

 

[The_Family_Tahoe]

The alternator diode(s) could have shorted; that would not be affected by the fuses.

However, I'd also expect higher amperage draw. I don't worry about parasitic drains under about 0.2 amps. I'm not sure of your meter reading--you're saying you have a drain of .014 mA? Or .014 A?

Are you sure the battery is not self-discharging via the conductive slime that builds-up on the case? CLEAN the battery case.

Disconnect both battery cables, FULLY charge the battery so that it has 12.6--12.7 volts AFTER it's been off the charger for an hour. (It'll maybe have 13+ volts when fully charged and fresh off the charger.) See what happens.

The battery may be plain ol' defective, unable to hold a charge.

With the meter set on 10mA the reading is .014. I don't know how to interpret that. Is that mA or A?
The battery looks visually clean with no residue or chalky build up. I will clean it thoroughly and confirm a full charge like you suggest.
It's raining here now so I may not make any additional progress until the rain stops

 

[HotWheelsBurban]

Does your Tahoe have the deluxe sunvisors with the lighted mirrors? The hinge points on the mirror covers control the switch for the lights(terrible design!) and when they break, the cover moves just enough to make the light come on. It'll definitely pull the juice outta the battery in a day or two, been there done that on both of mine! The visors are partially disassembled and the harnesses unplugged.... because they all eventually break!

 

[L31MaxExpress]

My van had a similar issue once. Ended up being the mercury switch in the underhood trouble lamp was never allowing the bulb to turn off with the hood closed. With the hood open it was on like it should be. That took some time to figure out.

I also had an alternator on the 99 Tahoe that was drawing 5 amps continuously from a shorted diode. That one was much easier.

 

[df2x4]

Does your Tahoe have the deluxe sunvisors with the lighted mirrors? The hinge points on the mirror covers control the switch for the lights(terrible design!) and when they break, the cover moves just enough to make the light come on.

My van had a similar issue once. Ended up being the mercury switch in the underhood trouble lamp was never allowing the bulb to turn off with the hood closed. With the hood open it was on like it should be. That took some time to figure out.

Both of these would be good things to check. I've had both of these issues in my '97s. The underhood lamp issue can be solved by bending the light housing down on the bracket slightly. A quick temporary fix for the sun visor cover is to jam a couple of toothpicks in the sensor hole, break them off and put a small square of tape over them. Or at least that's what I thought when I did it years ago, that temporary fix has become semi-permanent in my case. I have a new lamp/cover assembly but it's never made it to the top of the priority list.

 

[The_Family_Tahoe]

I checked the hood light and it is off when the hood is closed.
I checked the visors and these don't have lights.
Is my reading of 10mA =.014 any concern?