Hello, I have a 2002 monte carlo ss that has a huge battery drain, like below 10 volts within 8 hours of sitting. I have replaced battery, alternator, starter was last summer. Hooking up a multimeter doesnt show any draws instantly, it seems to happen intermittently. One Mechanic said it was a tempature sensitive issue? Can anyone help with this problem. They did test the radio to see if they was a problem but still had the draw. I don't know when it draws but did say it draws a volt when it does. Thanks

 

It doesn't show any draw at all- like absolute 0? I only ask because that in itself is abnormal for a modern car.

This is a good application for a data logging multimeter. You can set it up to measure and just let it run (and given it goes practically dead in 8 hours, you'll certainly capture the event before it runs out of battery / memory). Of course that won't tell you the exact circuit, but it will tell you exactly when it happened and how much it drew so you could eliminate circuits that couldn't physically draw that much due to fuse rating (ie if its pulling 25 amps, you can likely rule out all of the 5/10/15/20 amp fused circuits).

Absent that, you'd have to chip away at the circuits by disconnecting them until the problem goes away (to isolate the circuit). Obviously doing it one by one would be too time consuming, so you'd have to cluster them to narrow it down more quickly - ie disconnect all fuse boxes but one the first time, then rotate through them. Once you find the box with the draw, you can then narrow it down to the exact circuit.

The follow up question to that is - how do they know when they previously claimed the car has absolute 0 current draw? To make that assertion means they'd have to have seen something (in which case they should've explored that path further).

Unfortunately there's not much we can do remotely. You need someome to brute force through the diagnostics on this to isolate the circuit causing the issue.

Draws a volt as in the system drops 1 full volt with the radio on? If so, that's a serious amount of current draw. I'm not sure how else to interpret this - if they meant 1 amp, thats unusually low when the radio is on and unusually high when the radio is off - both of which should've prompted a deeper dive.

Thats an ultra specific circuit to be testing when they're not getting any current draw at all in the parasitic test. What caused them to investigate that circuit - is it an aftermarket radio? If so, my first step would be to pull the fuse on every aftermarket item to let it sit for 8 hours to see if it goes away.

The vast majority of electrical issues I've seen are caused by aftermarket stuff, so its always best to eliminate them first.

 

Here to update my thread as I haven't been able to get back on lately.

The last month I have been taking fuses out. Started with the one in the engine compartment and then the 2 panels in the doors. As I watched the battery volts drop I would say slowly, the battery stayed above 11 volts for a month so if I would have put them all back in it would have started up.

I did get out and drove it around for a Saturday afternoon. After not touching it for a couple days after. I went to check battery and it was less then 4 volts

i put the charger back on to get it charged up again.
after it was charged up. I simply just unplugged the charger and the battery has stayed up to between 12.75 and 12.50 over a week.

So if I am on to something that the battery drains only after driving and doing normal stuff. Something isn't being shut off after running. Does this narrow anything down to a relay switch or something?

Anything you would start with checking?

 

Sounds like something (like a solenoid or relay) gets energized when the car is started and running but doesn't de-energize after the car is shut off.
Three words — process of elimination.
The vast majority of electrical problems are caused by poor grounding. Current will travel via the path of least resistance. If a circuit is not sufficiently grounded, the current will travel through other components and circuits until it finds a ground, meanwhile causing those other circuits and components to behave erratically. For instance, a capacitor that is only supposed to be energized when the circuit is active cannot de-energize when the circuit is deactivated.
You won't follow my suggestion because it's laborious and seems like a waste of time, nevertheless; re-do all your ground connections. This means disconnect each ground wire and strap one connector at a time, clean the terminal and the area where it connects to with steel wool or a wire wheel, wipe off with brake cleaner, reconnect then move on to the next connector.

 

Had a friend that just bought the newiest code scanner do some tests on my monte over the weekend. It had multiple codes that refereed to the body control module. Does anyone have videos and Info replacing this? Buying a new one need programing, or am I able to find one with same ID from a junkyard? Thanks

 

Had a friend that just bought the newiest code scanner do some tests on my monte over the weekend. It had multiple codes that refereed to the body control module. Does anyone have videos and Info replacing this? Buying a new one need programing, or am I able to find one with same ID from a junkyard? Thanks

 

I was having a lot of problems with my cluster going crazy, and my fuel gauge lying to me as well as my new battery draining. Ultimately I solved the problem by changing the negative battery cable. Drove me nuts trying to figure it out. Good luck.