Jeep Wrangler Forum banner

Battery Drain

14K views 17 replies 12 participants last post by  jcscotson 
#1 ·
Hello everyone,

I have a small problem and was hoping for a little guidence. I have a 1994 Wrangler that has a power drain. I have tracked it to the Fuse maked "IOD and Horn". I know its not the horn, so can someone face me in the right direction at to what the IOD might be and where to look. I have not completed any wiring on the jeep in over two months and this just started. It takes about two day to completely run it down.

Thanks
 
#7 ·
my cherokee did the same thing and if i remember i just pulled the fuse for the iod and it stopped draining and i think everything worked still. it was a long time ago so im a little unsure. it did have a power antenna that had a draw as well.
 
#11 ·
If the IOD runs only small stuff like radio memory, interior lights, etc. WHY is the IOD fuse rated at 50 amps?

My Optima battery drains to fully dead in less than a week. I followed the drain through all the fuses until I pulled the IOD and the drain stopped. 2001 TJ Sport 4.0 automatic Trans. Any suggestions? please.
 
#12 ·
Apologies for bumping an old thread, but I am having this issue as well.

I think I am also drawing more from my battery than the alternator is putting back with my electric fan. I have it running off a switch in the cab and turn it on while driving. My battery died yesterday will diving around and I did have the fan & radio running. I just bought this jeep that was someone else's project apparently.

TIA
 
#13 ·
#14 ·
Start by simply one by one disconnecting anything that has power with the key off. Possibly the radio, power antenna as mentioned above, any aftermarket accessories and whatever else you can find.

Check the draw at the fuse terminals with a multi-meter after pulling the fuse and before disconnecting anything. Then go about disconnecting things, measuring at the fuse terminals each time you disconnect something. Once you see a significant drop in voltage draw, you have the culprit.

Other posters can tell you what the draw should be with just the radio connected.

TJ-Aggie12, check the voltage from your alternator. If you don't have a multi-meter, Harbor Freight has them for $6.00 or sometimes for free with another purchase. It should be a little over 14 volts. If not, take it to your local auto parts store for them to check it out.
If you are driving at highway speeds you probably don't need the aftermarket fan. Air rushing through the radiator from driving should be enough to keep your engine at proper operating temperature.
I suggest you get rid of the electric fan and install the factory setup. The electric fan is unnecessary unless you have space limitations, such as from a Small Block Chevy installation. If your pulley is still on the water pump all you need is a fan and fan clutch. A stock fan blade will serve you better than a flex fan.

Good Luck, L.M.
 
#17 ·
Simple test for that. 12V ish on battery key off engine off (KOEO), 14V ish on battery key on engine running (KOER). Start with the battery fully charged (leave on trickle charger for a few hours). If the battery doesn't put out 12V by itself, it's bad. If you get more or less than around 14V with the engine running, get the alternator tested because it is probably bad if it's less. If it's more, the alternator is easy to take out and put back in, so it's worth testing before fixing the voltage regulator in the PCM.

What year is yours? Not sure about TJs but I would assume the alternators are eternally regulated in the PCM.
 
#16 ·
I was searching through my FSM on an unrelated matter and found under "charging system" a reference to "Battery Discharge Through Alternator". It stated "Refer to MR279 for procedure".

I don't know what MR279 is...probably listed somewhere else in the FSM. My manual is for 1987 & 1998, but if you have the Delco type alternator, it could apply to your 1994 Wrangler also.

Just a hint. Before you blame the PCM, have the alternator tested. The test should be free at your local auto parts store.

Good Luck, L.M.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top