Idle air control problem

mainegirl

mainegirl

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Joined
Feb 12, 2019
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Location
fairfield, maine
Hope someone can help me figure this out. My 2004 6 cyl. auto jeep with 58,000 miles, has a parasitic drain somewhere. I did the usual pull relay/fuses put a test light on the battery cable (removed) and it only lights the light for an instant. I notices a faint ticking sound by the throttle body and discovered that my IAC is warm, and I can feel the vibration when it ticks! So I changed out the IAC with a new one and no joy it still does it! My question is what is causing it to do this? Do I need a new computor (I hope not), shouldn't the power to this turn off with the key? I am thinking of cutting the power wire to it and putting it on a switch so I can shut it off when not in use. It only takes a week of non use to make the battery go dead. I'm really discouraged and ready to sell it, can't find any mechanics that know anything any more, they just change parts, no idea how to diagnose. help!
 
A week is a long time to leave an old battery sitting around especially in cold weather. I'd bet even if you pull the IAC connector to test for a week the battery would still be dead. Try and find a way to hook up a standby charger.

It is common for the hood light to break off and stay on but that'll drain the battery in one day not a week.

If the IAC really is getting power I'd hook up a voltmeter to the connector so you can see it and then wiggle the ignition switch and see if you can get it to shut off. If it isn't the ignition switch you might have a pinched wiring harness somewhere that is shorting out, that wont be easy to find.

My opinion is the only part worth blindly changing out is the ignition switch, only if you have no other options.

Do not cut the factory harness for a switch, that is a really bad idea. Worst case get a set of mechanics gloves to throw in the Jeep and pull the IAC plug every time you let it sit for extended periods.

Sorry for the disjointed post, good luck with it.
 
pagrey said:
A week is a long time to leave an old battery sitting around especially in cold weather. I'd bet even if you pull the IAC connector to test for a week the battery would still be dead. Try and find a way to hook up a standby charger.

It is common for the hood light to break off and stay on but that'll drain the battery in one day not a week.

If the IAC really is getting power I'd hook up a voltmeter to the connector so you can see it and then wiggle the ignition switch and see if you can get it to shut off. If it isn't the ignition switch you might have a pinched wiring harness somewhere that is shorting out, that wont be easy to find.

My opinion is the only part worth blindly changing out is the ignition switch, only if you have no other options.

Do not cut the factory harness for a switch, that is a really bad idea. Worst case get a set of mechanics gloves to throw in the Jeep and pull the IAC plug every time you let it sit for extended periods.

Sorry for the disjointed post, good luck with it.
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I have a brand new really expensive agm 900cca battery (bought a Warn winch wanted something good to operate it) I put a new Mopar ignition switch in it when I bought the Jeep 5 years ago. It is in heated storage all winter and I do keep a Battery Tender on it at all times, but when I go up to hunting camp (off grid) I worry that it will go dead if I don't use it every day. The hood light works & like I said I yanked all the fuses & relays. It definately is the iac, if I go out in the garage right now It will be warm to the touch and making that faint ticking sound, you can actually feel it trying to do something if you put your hand on it, like it's stuck on or something. I guess I'm going to have to find a wiring diagram somewhere to see what powers the darn thing up and what sensors cause it to function. I am a Ford person, this Jeep stuff is not familiar to me. Thank you very much for your ideas, I'll try the switch wiggleing idea, It's just such a pain when we want to go for an ice cream or quick ride, to frig around with the charger and hood, and I'm getting older and don't trust it to go way up in the mountains to camp all alone (16 miles up a logging road, no phone service) , I have a ton of money in it and it is exceptionally maintained, but this is just saddening. It only has 58,000 and has never been driven in the winter or mudded. Thank you for your help!
 
I doubt it's actually the IAC itself, especially since you changed and the symptom was the same with the new IAC. If indeed it's the IAC causing the drain, and I'm not yet convinced it is, the root cause of the IAC problem is likely inside the PCM (engine computer). The IAC has four connections that go only to the PCM so if one of the drivers (a transistor) has gone bad and it's keeping the IAC energized, that's a problem that is only curable by replacing the PCM. It's theoretically possible for a small minority of electronic techs to maybe repair the PCM but it'd be hard to find someone qualified or willing to do that level of repair.

Did you do measure the amperes being pulled out of the battery and then disconnect the IAC to see if that significant drain went away upon doing so?
 
Jerry Bransford said:
I doubt it's actually the IAC itself, especially since you changed and the symptom was the same with the new IAC. If indeed it's the IAC causing the drain, and I'm not yet convinced it is, the root cause of the IAC problem is likely inside the PCM (engine computer). The IAC has four connections that go only to the PCM so if one of the drivers (a transistor) has gone bad and it's keeping the IAC energized, that's a problem that is only curable by replacing the PCM. It's theoretically possible for a small minority of electronic techs to maybe repair the PCM but it'd be hard to find someone qualified or willing to do that level of repair.

Did you do measure the amperes being pulled out of the battery and then disconnect the IAC to see if that significant drain went away upon doing so?
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I don't think it is the iac itself, but the component that is causing it to stick on, in a weird pulsing way. I tried to measure the voltage, but lost my patience waiting for it to tick on. (sometimes it does it every second, sometimes its a few seconds apart, and my attention span is terrible!) I guess I should unhook it to see if that stops the drain, and I am almost positive it will, because the fact that it is getting warm and ticking means it is obviously using energy. But I should go out and unhook it & try that! There is still 2 feet of snow up here and cold, so I don't need to get it out yet, good time to fool with it if I can get a day off again. I was really hoping it wasn't the PCM, but after your explanation of the 4 connections going only to the pcm, I fear that is what is causing it to stick on. I was hoping someone else had this problem and it was something simple! I don't mind buying one, but I want to make darn sure that is the cause first! Thank you very much for your help, I really appreciate it!
 
I think fuse 12 behind the glove box supplies power to the PCM, you can check current draw there too if that's helpful. It's also an easier to pull than the IAC. It will wipe some of the memory but so will a dead battery.

I carry an inexpensive ham radio (uv-5r) and program it with the local repeaters when I'm out past cell service. You don't need a licence in emergencies and they cost about $25.
 
pagrey said:
I think fuse 12 behind the glove box supplies power to the PCM, you can check current draw there too if that's helpful. It's also an easier to pull than the IAC. It will wipe some of the memory but so will a dead battery.

I carry an inexpensive ham radio (uv-5r) and program it with the local repeaters when I'm out past cell service. You don't need a licence in emergencies and they cost about $25.
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I used to unhook the battery when I was at camp, but it's such a pain to sit there and baby sit it while it relearns itself how to run again, (not to mention it scares the crap outta me that it won't run right again if I keep doing that!) so I stopped doing it. I would sure like to learn more about Ham radios, that would be a life saver to alot of us older folks if it worked up there! We are in an unorganized territory in the middle of old paper company land amongst the mountains, so I'm not sure their are any towers that would work, but I need to find out about it, for emergencies that would be very helpful! I know tv & fm radios don't get any reception, but we go up there to get the heck away from all that! I was wondering if I left something on the gas pedal if it would shut off the iac (seems like I read that somewhere, that giving it the gas shuts it off) or am I grasping at straws? Thanks for the help, and thanks for the idea on the Ham radio!
 
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