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Dead battery

I recently had a brake controller installed on my dodge ram 1500,1999 with factory tow package. Ever since, my truck battery goes dead between uses. I’ve replaced the battery and also the instrument cluster.The mechanic said the instrument cluster was drawing power from the battery. The battery is still discharging. They say it has nothing to do with the brake controller., but the truck was fine before I had the brake controller installed.


By “brake controller” do you mean a sending unit for electric trailer brakes?

If the controller works properly, it seems unlikely that it is the source of the problem, but it should be easy to find out if there are plugs or fuses that will completely disconnect the brake controller from the truck.

Yes, the brake controller is for pulling a horse trailer, I’ve disconnected the unit in between uses, but still the battery discharges. Does this ruin the battery? It’s just been replaced.

Automotive starting batteries are designed to be discharged to about 50% of their capacity, IIRC. Repeatedly discharging the battery to less much less than that will damage it. If it is recharged immediately, the damage will be minimal. The longer it goes before recharging it, the more the damage.

The brake controller should NOT be discharging the battery. I have one (Drawtite) then I leave hooked up all the time. I only tow a camping trailer during the summer. As long as no trailer is hooked up to complete the circuit it should NOT drain the battery. Something else is going on here.

they wired a short to ground

what do you mean?

A “short to ground” results in a smoke test, not a slowly discharged battery…

An ammeter can be placed between the battery and the disconnected + cable. This will read the current draw. It should be less than 150MA. If it’s higher than that, pull fuses until it drops to below that number. Troubleshoot the offending circuit.

I agree, but it could be a defect in the controller. My guess is the controller is defective or it was improperly installed.

do you have the wiring harness for the trailer clean, dry and not plugged in to anything else?

think back to when the controller was installed. any thing else installed around then? cb radio? multi cigarette plug? change the radio? anything???

Pull the fuse (I think it’s a 40A fuse) for the brake controller.

I have a 40A fuse for the (Prodigy) brake controller in my Tahoe. Without this fuse there won’t be any power going to the controller.

even when the Prodigy is unplugged, the truck won’t start. Nothing else was installed at the same time, do I take this truck back to the guys again, or go to a place that installs these. I’ve already spent alot of money on this. would a faulty plug or wiring harness affect the battery if the controller isn’t plugged in?

ANY competent shop can perform a “Parasitic load test” and isolate the problem. You are making a big deal out of a small problem…

12hooves you are not alone! I had a prodigy installed on my 2008 Jeep Liberty last weekend and have the same problem! Every morning I come out to find the battery deader than dead. And it doesn’t seem to matter whether the controller is actually plugged in. I’ve contacted the installer and taken the vehicle in to the dealer (for 2 days!), and no one can identify the problem!