Hello!

I have a 1999 ZR2 that seems to be having problems with the battery/charging system. I just bought it about a month ago. I have found that if i leave it sit for 2 days or so the battery is completely dead, not even enough to use the doorlocks/interior lights. If i jump it, all is well and seems to be okay as long as I drive it frequently. I suspect the battery not holding a charge, but it has a sticker on it saying it was just bought in Apr. of this year. The alternator is also new. So i figure I either have a bum battery or something in the truck is draining the battery while it sits. None of the lights in the truck are staying on, however, I have the factory alarm, it activates and eventually the security light goes out. After it sits for a while, the BRIGHT headlight indicator on the dash comes on and seems to stay on until I unlock the doors and deactive the alarm.

Is this normal that this comes on? Is this an indicator that the alarm is active, or an indicator that something in the truck is running and draining the battery? I cant seem to find anyhting about it staying on in the manual. I dont suspect that the indicator light is enough to drain the battery in a couple of days, but perhaps it is an indicator of something else that is? or then again, maybe just a bum battery.

Thanks in advace for you help!!

-Bryce

 

Thats perplxing to say the least.

Do you, or did the truck have an aftermarket security system?
They typically stay on while the engine is off.

 

Well there's one of a couple things I'd do. first off shut down the truck and then pull the terminal off the battery when you know it's gonna sit for a day or so and leave it sit with the terminal off... then after a couple days when ya go to start it. If you have plenty of juice then you know it's not a bad battery as it's holding a good charge when nothing is drawing on it. now if you see the battery is good. I'd go invest in a descent volt meter that will do current too. Try to get somethign that'll handle 10 to 20 amps of current. then shut the truck down and pull the posative terminal off set the meter up for amps and put the red wire of the meter on the battery and the black wire of the meter on the posative terminal and see how much current you're pullin'. Then I'd go into the fuse box and start pullin' fuses. Pull one fuse then check the current see if it dropped considerably. if not. replace it and repeat for all fuses until you find the one that when pulled the current drain drops considerably. once ya find the one that stops the drain on the battery then ya got a damn good place to start lookin' for the component that's doin' it. When ya find the circuit that's pullin'. post results and one of us here can probably pull a schematic of that circuit and post it. so you can start pullin' connectors to components in that circuit to find the one that's pullin' the current....

 

ok try this....in my 1996 blazer there is a glove compartment light.....if not closed right it drains the battery....happend once...and i went in at night and saw this spec of light i opened it up and the glove compartment light was the cause, i was pretty pissed but hey least i figured it out

 

Well i know it has been awhile since the last post in this thread. Here are my results.

I finally invested in a multimeter that measures DC amperage. I put the meter in series on the positive battery cable. It seemed that with the interior lights off I was sitting at a constant .78 - .80 Amps with the truck off, no key in the ignition. I pulled every single fuse one at a time (Interior and under the hood) the only one that seemed to make an markable diffeerence was the one fuse labled RDO, IGN. with this fuse pulled, i was drawing a stead .20A. So that circuit is drawing .6 amps. This fuse seems to affect my speedometer, tachometer, gas guage, radio head unit (Factory) and my factory CD Changer. (That is what I could tell was off anyway)

I have left that fuse out and leave it for a couple days to see if it drains the battery. Unfortunately, I need to leave this weekend with the truck and cannot leave it sit until next week, but i will give it a shot.

My question is this... is .6 Amps enough draw to drain the battery if it is left sitting 24-36 hours? Should there be ANY draw on the battery at all with the truck off (I am sitting at a steady .20A) I realize that the radio needs constant power to keep the clock time etc. but .6 amps to do that seems a little much. Is the .2 amps I am left with being drawn from the battery a reasonable draw for things that need constant power in the truck?

Does anyone have any wiring diagrams as to what would be on that specific circuit?

Thank you all so much for your replies!!!!!!!
-Bryce

 

I'm certainly not an electrical whiz but I was doing some reading. It takes about 20 minutes after you shut off the engine and remove the key for your class 2 devices to go into "sleep" mode, so your draw will be higher for those 20 minutes.
The calculation for battery drain is:
Note the battery reserve capacity. .
Divide this number by 4. Example: 90/4 = 22.5
Compare this to the ammeter reading.
The current drain in milliamps should not exceed this number.
Example: if a battery has a reserve capacity of 90 minutes, the current drain should not exceed 22 milliamps

When the current draw is too high, remove the electrical system fuses one at a time until the draw returns to a value less than or equal to specifications.
Start with the fuses that are hot all the time.
To remove the fuse, you must first open the door, which causes a high enough current flow to damage the ammeter.
Protect the ammeter, without disturbing the electrical continuity, by turning on the test tool before opening the door.
Remove the courtesy lamp fuse.
Note the ammeter reading.
If the parasitic load is still excessive, start removing the remaining fuses one at a time.
Keep the courtesy lamp fuse out during diagnosis, so the door can remain open.
Removing the PCM or VCM fuse should cause a drop of less than 10 milliamps. A drop greater than 10 milliamps indicates a possible short to ground.
Check the orange wires at the PCM or VCM along with the components connected to the orange wires. No drop in the milliampere reading indicates the PCM or VCM is not drawing current.

Hope this helps a bit.

 

.6 amps is 600 milliamps and yeah... for those components to draw a half amp seems a bit much to me when the engine is off.... now if that cluster goes to sleep after 20 min. I'd test it then and see.. if it's still up around that high after about a half hour... then I'd say yeah.. there's a problem... but what I'd do is hook that meter in and let it sit for about 30 min. don't wanna remove then readd power and "Wake them back up" but if it's still up around that high... I'd start pullin' harnesses to components and start with your stereo and cd player first.... do you have a power antenna? and if so does it stay up when ya shut the truck off?? if so it might be pullin' current tryin' to keep driving the antenna up. OR could be that a relay in the stereo is sticking and keepin' the finals (amp section of the stereo on) in what's called a quescent state and pulling minor power. so that's what I'd start pullin' first to see....

 

My Bonneville flows 0.08A when everything is asleep and about 0.25A for 10-15 minutes after key-off.

*EDIT* - had to look up what I actually observed when my battery was on the fritz. Just ran out to check my log

 

Hello all again!

So i have narrowed it down a little more. After leaving the truck sit for 30 minutes I am now sitting at .09A. I tore off all the panels inside the truck and started pulling connectors on the RDO, IGN circuit. I have found that when I pull the connector off of the guage cluster itself, the draw drops from .80A to .09A which seems much more reasonable draw. This also seems to make a little sense as I am having problems that the speedometer doesn't work either (See my other posts) so I figure that the problem is internal to the guage cluster.

So my question is....... being that the current being drawn drops that signifigantly when the gauge cluster is unplugged, would the problem be internal to the gauge cluster, or could it be something to do with the wiring to/from the gauge cluster?

Does this make sense?? One more thing... if it is internally in the gauge cluster, could I buy a used one and have GM program the KM into it, or do I have to buy it new from GM to have this done?

Thanks again for all your help!

-Bryce