For the last few months the battery on my 2007 LandRover LR3 has been draining. I had it looked at by two different mechanics and they both say the GEM module needed to be replaced. So my question is does a GEM module need to be programmed for each vehicle or is it just plug and play? I wanna make sure I know what I’m getting myself into before I make any purchases.

 

There is no GEM module in an LR3, per say. In a Disco two there was a GEMS engine, but that is only thing GEM I can even think of on a Disco. So maybe they are talking about the CJB? But if they cant get the term right, I would not trust them to touch anything at all. And if they are taking about the CJB, I really doubt if it is causing a drain. You can not replace them easily, they are hard encoded on the production line and if you swap a used on in you will have VIN mismatch errors and you may have other issues due to software compatibility.

 

Any other ideas on what could be causing the battery to drain then? If it’s any help background I had the dreaded sunroof water leak that many other have talked about here.

 

Connect an ammeter in series with the negative battery terminal. Current drain after everything has gone to sleep should be something like 0.05 amps/50 milliamps. If higher start pulling fuses until it drops.

 

When you say, "Connect an ammeter in series with the negative battery terminal," is that just ammeter black to battery terminal black + ammeter red to battery terminal red, or something else?

 

You disconnect the battery negative lead and connect one ammeter/multimeter lead to that cable and then the other meter lead to the battery post. If using a multimeter make sure the leads are in the correct Jack's and it is set to read current. You may see negative amps, such as -0.100. That just means the leads need reversing. It still means a 0.100 Amp current drain.

 

I just got new info from the repair shop, and they said the problem is being caused by something in the body control module not fully turning off when the car gets turned off. Do you know anything about this part? Can I just swap a new one in?

 

If it is at a shop and they know the issue, why not have them fix it?

I never heard of the BC module causing a drain, but I suppose anything is possible. Keep in mind that even when the Rover it turned off, there are shutdown delays. For example, infomat takes two minutes. And the EAS states live for a while and wakes up a couple times later. But dont believe the module is VIN hard coded and if I recall it can just be swapped.

 

I would have them fix it there if I could; they say I have to take it to a Land Rover dealer, which is going to cost me a small fortune.

 

I think the used modules are cheap on eBay. But if you dont want to spend money, you should do as outlined above when it comes to tracking power drains and get yer hands a little dirty, see what you come up with! Worth a shot.