Today went to jump in my 1995 12V, flat dead- so it must have a drain somewhere. I put the 10 Amp charger on it for the night, as I turned out the lights to the shop I noticed the parking lights were on, but very dim. When I open the door to the cap they go completely out, close the door they come on dim? Turn them on with the headlight switch and they are bright and act normal. As the battery's got some charge they stopped sticking on dimly and all seems well. Any ideas on what on earth caused this? Maybe it was my New headlight switch and overlay relay recall 819 I installed a few years back causing this?
Recall 819

 

Any lights attached to the cap door? Brake light? Interior light inside the cap? Start looking for the shorted wire or missing ground.

 

If you have a 7 pin trailer connector on the rear of the truck, it's fairly common for the inside of it to become full of mud and corrosion that can partially bridge two circuits together. As the tail light pin is right beside the 12 v pin, it's quite possible that this is your problem. I'd take that connector apart and have a good look inside.

 

I thought about the trailer connector until he said that it changes when you open and close the cap.

 

now that the batteries are up, no more strange parking light problems. But there is a drain somewhere that's pulling the batteries down over a weeks time. I will check into the trailer connector and also the 4 pin marine connector that the previous owner installed.
Joe

 

I added a post yesterday about finding parasitic drain, then I deleted it because it looked like you had solved your problem. I guess I will put the information back now.

First of all let's keep in mind that with things like radios and security systems, you will always have a bit of a draw, even when the truck is turned off.
To find your total draw when the truck isn't running, disconnect the batteries, make sure doors are closed and the under-hood light is removed (you don't want to get an artificially high reading because your underhood light is on). Reinstall one negative cable and then using your multimeter measure the amps between the positive cable and the positive battery post. You now know your total current draw when the truck is turned off.

One of the more experienced folks is going to have to help with this next bit. I can't remember what the total expected draw is for our trucks when they are turned off. If your reading is higher than normal then you need to start looking for the problem. This is where the cool trick comes in.

Start removing fuses one at a time. When you remove a fuse, measure the current draw for that circuit by using your multimeter on amps and place the multimeter probes on the two contacts for the fuse that you just removed. Write down the circuit name and current draw and put the fuse back in. Go through each of the circuits and you will eventually find your parasites. The inside fuse box can only be accessed with the driver side door open so don't forget to push in the door contact switch so the light isn't on when you get to that particular circuit.

Also, don't forget that there are 2 fuse boxes in our trucks, one in the cab and one in the engine compartment.

Hope that helps.

 

Good advice above from Tallguy. I'd like to emphasize that you need to install your ammeter in series with the battery connection and THEN let the vehicle sit and time out for probably time out without disturbing the connections. (As soon as you unhook batteries and install the ammeter, it will wake up all the modules and they will need to time out again before your draw reading will be accurate.) Also, if your truck has dual batteries, make sure you disconnect the battery you are not measuring from, beforehand, so it won't be supplying any of the draw current.

Dodge's spec for acceptable ignition-off draw is 30 milliamps (.030 amps) after all the modules have timed out.

 

Thanks for the added information Torquefan, I forgot about things like the seatblet modules pulling a fair bit of current when power is first applied. I think the seatbelts take 20 minutes to timeout and stop drawing amps.