Our Community is 940,000 Strong. Join Us.

Battery drain: LoJack?

03-30-2022, 03:19 PM
I keep accidently deleting my post after long paragraphs of info have already been typed up some sort of way. This is my third attempt. I'm getting frustrated so please bare with me. I doubt make model and year have anything to do with the problem I'm having but I have a 2004 Chevy Avalanche.

I was playing my music (aftermarket stereo and amp) from the truck while working on another project. Eventually the battery went dead. i jump started the truck and I thought everything was okay but it wasn't. After driving around to charge the battery a bit but the next morning my truck did not start. I tried a few things but long story short I ended up buying another battery. The next morning same result, my truck did not start.

A mechanic buddy of mine spent a full day trying to find a drain but could not pinpoint anything. He did however rewire the battery connections. This seemed to have fixed the problem for a little over a week. Well it all came to an end and my truck did not start in the morning for the last two days.

So I'm sitting in my truck this morning and I remember a device that fell from under my dash awhile back. I assumed it was a component of a Lojack system I had installed years ago when I first bought the truck in 2005. My truck is now old, so in my mind I'm thinking my truck is probably not worth stealing again so I wasn't immediately concerned about the part that fell . The part that fell looks like a battery pack. It occurred to me the LoJack might be draining my battery without this battery backup (if that's what it is).

And yes, I said my truck was stolen before. I had a kill switch installed.
I started looking in the area where the LoJack Device came from, which is also the area where my kill switch is. I notice a non-factory splice in the wires. GM didn't do it. I didn't do it. I don't think my stereo/alarm guy did it. I think either the LoJack guy or the kill switch guy did it. I'm going to follow up with LoJack or whoever is taking over for them and will include my findings later, but I wanted to start a thread to see if anyone had any input. I will also try to include some pics later as well.

03-31-2022, 12:50 PM
So I got off the phone with LoJack. They're not entirely out of business but I was referred to what they call their "legacy program" which wasn't any help for my situation. They no longer have technicians to help or service any issues with their product. I was told that their device is not electrically connected to vehicles even though there are a pair of wires hanging out of their device. The only thing the agent on the phone could do for me was confirm that the device I had was in fact actually theirs. Only problem is, their device is identified by a 7 digit number which is on a label. Well the label was stuck to the tape that was wrapped around the device and came off when the tape was removed. I still have the tape but I would have to take some extreme measure like steam the label from the tape or something and I'm not even sure what that would do for me anyway.

So now I guess my only recourse is to look up some "how to find battery drain" videos on YouTube. Either that or start looking for a new truck.

03-31-2022, 01:20 PM
If you have a test light, or better yet, a digital multimeter with current meter, or a clamp-on DC current probe, you can measure the current flowing from the battery, then pull fuses one at a time to determine which circuit is the majority of the drain. The reason a clamp on probe or series DMM is preferred here is because it would allow the system to still transition to a standby state. With a test light it may not allow enough current for the system to function enough to even enter standby.

Once you confirm there's a larger than spec draw on the system (probably something more than 100 mA) they you can start pulling fuses one at a time to see which one causes the current draw to drop to a low rate. Then, using the fuse diagram or a factory wiring diagram, track the various items on the fused circuit to further determine where the draw is coming from. Maybe you'll be lucky and it will simply be a glove box light that isn't turning off or something simple like that.

If you don't have the wiring diagrams but can determine which circuit is suspect, post back and someone here can likely help to better define what items are on the circuit from the factory.

Have you checked the battery voltage at both the battery and at the clamps (GM side-post clamps can make measuring the battery voltage tricky) static and when the key is in the Start position to confirm if the battery voltage is the issue or if the system isn't trying to engage the starter?


05-11-2022, 08:56 PM
If you do use a clamp on Amp clamp make sure you use a name brand that has a high resolution testing ability. It would be better to install a multi meter that is capable of reading current inline with your positive battery cable.

05-13-2022, 04:05 PM
Have you checked this issue out any further? Or found your problem?

Add your comment to this topic!