Lexus IS Forum banner

1 - 20 of 23 Posts

·
Registered
Joined
·
32 Posts
Discussion Starter #1
Hey guys, so yesterday i got in the car and it wouldnt start cuz the battery died. so i jump started it and got home fine. i turned the car off and and 5 seconds later it still started right back up. Then 30 min later i tried again and it wouldnt start. i heard weird noise coming from under the hood. sounds like a buzzing sound. so i went and bought a new battery and plugged it up and let it sit for a day and today in the morning when i was leaving for work i heard the same buzzing sound. I left the car parked for a day and wen i got home i tried starting it, the battery was dead. Wat is going on!?!?!? im trying to sell the car and i really need help fixing this issue.
i just relocated the battery to the trunk cuz of my turbo setup but other then that nothing else is plugged up to the battery. im running thick cable from trunk to fuse box.
 

·
Super Moderator
Joined
·
19,540 Posts
Try to locate the place where it is buzzing. The ignition switch has been known to go bad causing the EFI relay to buzz and chatter, but honestly it could be many things. You don't want your car to draw more than 70mA after 5 minutes, that should be your parasitic draw. Mine is 47mA after 5 minutes and stays steady. You will need a DC amp meter or multimeter with a DC 10A scale. I would have the battery tested for free but the source of the drain needs found. Once you know the total draw, you can start to isolate what's wrong OR if you can find what's buzzing.

Skip down to parasitic draw

Http://my.is/forums/f221/diy-charging-system-full-diagnostic-alternator-battery-426000/
 

·
Registered
Joined
·
32 Posts
Discussion Starter #3
So i got the battery checked out and everything is fine. I got closer to the problem tho. The only problem i have is that the car recharge mode is a little weak. The buzz sound is coming from the TPS sensor and when i unplug it i can hear the butterfly shut off. its as if the TPS is keeping the butterfly open even when the car is off causing the TPS to stay on. So i switched out the TPS and still the same problem. i also have a problem with idle. It surges from 500 to 2500 over and over again until i start it on warm starts. BUT on warm starts its hard to turn over and the car has a problem starting. PLEASE HELP ME!!!
 

·
Super Moderator
Joined
·
19,540 Posts
What do you mean by car recharge mode, the charging voltage at the battery when the car is running? As long as it's 13.2 or higher, it's fine(mine is 13.5 when the car is at operating temp).

The buzzing you hear is coming from the throttle control motor, it's supposed to hum when the throttle wheel is turned. If it is keeping your throttle open and humming when the car is off then most likely the ignition switch is faulty. The throttle control motor shouldn't hum unless you don't have the pedal position sensor at rest. Also, you have to specifically set the TPS, either using a scanner or voltmeter. There's a video by Nyke and several Diy's around to show how.
 

·
Registered
Joined
·
32 Posts
Discussion Starter #5
Thats wat i meant the charging voltage. I adjusted the TPS to .64-.65
I think the problem is i relocated my battery to the trunk cuz of the turbo installation and i ran the ground wire to the front of the car and grounded it on the frame but really close to the engine and im thinking the reason it is hard to start when the engine is warm is because the frame is warm too and maybe that is affecting the ability of the ground wire.
 

·
Super Moderator
Joined
·
19,540 Posts
Thats wat i meant the charging voltage.
That's what i thought you meant, just wanted to be sure. But yea, 13.2v or higher is fine. Anything below that is a problem which may be attributed to low battery voltage, poor grounds, weak alternator(which will usually give a battery indicator), etc. The battery should read 12.6v or higher when the car is off, otherwise it's not fully charged.

I adjusted the TPS to .64-.65
I think the problem is i relocated my battery to the trunk cuz of the turbo installation and i ran the ground wire to the front of the car and grounded it on the frame but really close to the engine and im thinking the reason it is hard to start when the engine is warm is because the frame is warm too and maybe that is affecting the ability of the ground wire.
Yea, when temperature goes up, resistance of a wire/conductor goes up as well. I actually thought the negative of the battery should go right to the engine block termination point(right by passenger side motor mount). Regardless, the frame, block and body should be grounded.

What concerns me is that you have a humming TCM when the car is off. Normally the TCM won't hum until the throttle cable wheel is turned and the car ignition has to be on. Again, if you are experiencing humming of the TCM when the key is out if the ignition, you have a bigger problem and i guarantee your battery will die very quickly. You either have a short somewhere in the ignition circuit or your ignition switch is faulty. You can rule the ignition switch out easily by removing the connector on the ignition cylinder. I know there's a common issue with '01's especially, where the cylinder switch would short out and the EFI relay would energize. So what i would do is try turning the throttle wheel with the car completely off. If turning the throttle wheel makes the TCM hum, pull the EFI relay and see of it stops. There was actually a TSB for this on the first year of the IS300.

I'm inclined to believe the thread below is your problem, which is the EFI staying closed when the car is off. It shows how to narrow down and repair the microswitch. When your car is off the EFI relay should not be on, and this powers up basically everything including the ECU. The relay may not be clicking, it just may be on. You can also try swapping that relay with the horn relay to rule out a bad EFI relay.

http://my.is/forums/f115/fast-clicking-sound-under-fuse-box-next-battery-438600/
 

·
Registered
Joined
·
32 Posts
Discussion Starter #7
Honestly im a visual learner so i wish there were some pictures explaining how to do all of that. But ill try to figure it out.
It's not the TCM humming it's the TPS
But What do you think about the "trouble starting the car on a warm engine" problem?
On cold starts it's fine but when it's on a warm start the car has problems turning over. Could it be the starter solenoid going bad?
 

·
Super Moderator
Joined
·
19,540 Posts
I honestly have never heard of the TPS humming, nor have any clue how it could hum because it is only a dual redundant potentiometer. Not saying i don't believe you, just doesn't make sense to me. Can you post a video?

If the battery has the proper charge and the solenoid just tries clicking instead of turning over, it very well could be the coil on the solenoid. You can always pull it out and have it tested for free. I'm not sure if you have an issue with slow cranking or the starter won't engages at all.

What concerns me is that it sounds like your ECU isn't shutting down and it's like the ignition switch is stuck in closed position.
 

·
Registered
Joined
·
32 Posts
Discussion Starter #9
Well i just found out my starter is going bad that is why even on the cold starts it takes longer to start. A mechanic told me the reason it is harder to start is because the bushings on the starter are wearing out. next time it hums i will record it. but i honestly think the reason for battery drainage is because of the bad starter that is draining power even when the car is off. the reason im ruling out the humming TPS because when it hummed i unplugged it and when i plugged it back in it stopped but the battery still drained completely.
 

·
Super Moderator
Joined
·
19,540 Posts
Well i just found out my starter is going bad that is why even on the cold starts it takes longer to start. A mechanic told me the reason it is harder to start is because the bushings on the starter are wearing out. next time it hums i will record it. but i honestly think the reason for battery drainage is because of the bad starter that is draining power even when the car is off. the reason im ruling out the humming TPS because when it hummed i unplugged it and when i plugged it back in it stopped but the battery still drained completely.
As soon as you touch the accelerator pedal just a tiny bit, the TCM will hum and continue to hum because it's not a stepper motor, it has a clutch. If it comes on during ignition only with no gas pedal, then there is a problem and it may just be the TPS needs adjusted. Make sure there is a tiny bit of slack in the throttle cable and the accelerator pedal position sensor is at rest. I still believe it waa your TCM that was humming, there's nothing to hum in the TPS.

Anyways, what i believe happened is that your ignition switch may have failed, that way the ECU never fully shuts down. I would suggest pulling the EFI relay near the battery when this happens. This will continuously kill batteries until it is found.

The only true way to find out where the draw is by using a multimeter with 10A AC/DC current reading capability, one can be had for $15. It will tell you which circuit is drawing amperage. It should be less than 50mA (after 5 min) and anything more will kill a battery in a few days. There is a starter relay that closes the coil on the starter for the solenoid to kick in.

This is aside from the starter. They have specific bench tests for starters at nearly any auto store. Make sure to have it tested for free at least once IF the starter really is drawing excess current. I really am not sure what to think about it, I'm sure if the bushings/bearings are worn then that's another thing. Two independent problems i believe.
 

·
Super Moderator
Joined
·
19,540 Posts
To add, you can test to see if the starter coil or B+ connection is drawing current by doing a DC amp test. The very next thing you do is find the source of the drain and what stays on. See if you have voltage on TC at the TPS(5v)

And DEFINITELY keep the battery disconnected when the car is off while this is sorted out, or you'll be buying another.
 

·
Registered
Joined
·
39 Posts
I'm not sure what the humming would be, but this has happened to me twice. Come to find out, there is a fuse that has a continuous draw that I found. it has to do with the Locking/Unlocking or AutoLock option in the car. I can't remember which fuse it was specifically, But it is in the passenger side kick panel if that helps. It's a really slooowwww draw, but over time it will put enough strain on your battery to deplete it. Both times this has happened to me, I was out of town and left my car sitting for 3-4 days. Come back, and dead. Charged it back up, would start right up if i started it within 5 minutes, but left it for an hour or so, and completely dead again.

hope this helps with the battery issue.
 

·
Super Moderator
Joined
·
19,540 Posts
I'm not sure what the humming would be, but this has happened to me twice. Come to find out, there is a fuse that has a continuous draw that I found. it has to do with the Locking/Unlocking or AutoLock option in the car. I can't remember which fuse it was specifically, But it is in the passenger side kick panel if that helps. It's a really slooowwww draw, but over time it will put enough strain on your battery to deplete it. Both times this has happened to me, I was out of town and left my car sitting for 3-4 days. Come back, and dead. Charged it back up, would start right up if i started it within 5 minutes, but left it for an hour or so, and completely dead again.

hope this helps with the battery issue.
That must be MPX-B fuse, it'd always hot with one of the radio fuses, and ECTS. They'll definitely be a certain drain, just depends on how much.
 

·
Registered
Joined
·
39 Posts
That must be MPX-B fuse, it'd always hot with one of the radio fuses, and ECTS. They'll definitely be a certain drain, just depends on how much.

Yeah, I believe that was it. I checked every single fuse and relay in my car and it was the only one that was still hot when the car was off. Ergo, my only suspect in my battery drain. haha I disconnected it for a month and locked/unlocked my car manually, and left my car sitting for 3-4 days when on trips. Didn't have a problem, so I assumed it was the culprit.

Hope belarusgangsta finds where the drain is though.
 

·
Registered
Joined
·
32 Posts
Discussion Starter #15
So i found out my ignition switch is going bad causing the ECU to stay on. but here is my latest problem. The car has a starting problem. on cold starts it turns over a little more than needed but still starts but on hot starts its really sssslllllooooowwwww to turn over and still wont start. i did a turbo build on my car and installed 830cc injectors. im thinking maybe the stock fuel pump is going bad or am i way off?
 

·
Super Moderator
Joined
·
19,540 Posts
So i found out my ignition switch is going bad causing the ECU to stay on.
That's what i thought and even suggested, so that's good you narrowed that down. I guess the contacts aren't made the best because this seems fairly common, especially with '01's.

but here is my latest problem. The car has a starting problem. on cold starts it turns over a little more than needed but still starts but on hot starts its really sssslllllooooowwwww to turn over and still wont start. i did a turbo build on my car and installed 830cc injectors. im thinking maybe the stock fuel pump is going bad or am i way off?
Yea, may be. I would verify the pump is getting full voltage during crank. I don't think the ECU would run it at slow speed but you may need to verify if you have the right pressure.

Now if you're referring to how slow the starter turns, you could have a starter going bad(open windings, brushes, etc) or starter relay, that's providing you don't have a battery drain when the car is hot, therefore poor cranking current. Test the voltage of the battery when the car is hot, could even be heat soak.
 

·
Registered
Joined
·
32 Posts
Discussion Starter #17
Thank you guys for all your help.
Well i just replaced the starter so thats out. Im ready to rule out the fuel pump because i read that if the problem was a fuel pump then the car would have problem accelorating at high speeds...minen doesn't do that. So now im down to either a fuel filter. Or maybe some sensor that acts up when its warm. Tell me more about "heat soak"
My battery is located in my trunk. Ive had it tested after driving and it still charges fine. There is a little battery drain wen car is off. It went from 12.61-12.59 in 2 minutes so im thinking thats because of the ignition switch.
If anyone figures out this fuel problem ill buy them anything they want/need online. $20 worth
 

·
Super Moderator
Joined
·
19,540 Posts
There's no doubt the ignition switch needs replaced or your battery will die very quickly(the ECU stays on). I didn't think you'd replace your starter, i thought you were going to have it tested for free as most places do.

What i meant about hot temperature is to check the running voltage at the battery when the car is running and hot. Some alt's act up and diodes fail when hot and under stress. If you have a current meter, you can see of there is a draw to the starter but i doubt it, the relay is open anyways.
 

·
Super Moderator
Joined
·
19,540 Posts
ssssoooooo any ideas on the problem?
For one replace the ignition switch. Not is only causing the ECU to stay in and drain your battery at a very high rate, it may also have something to do with why the starting the way it is. The ignition switch kinda ties to both problems here, at least it seems to me. The starter solenoid is picked up through contacts in the ignition switch.
 
1 - 20 of 23 Posts
Top