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I know this topic has been beaten to death on dozens of threads, not just on this site, but other forums as well. I've read the posts. My problem, however doesn't seem to fit any I've come across yet. Any input from people who have encountered, or tackled a problem like this would be greatly appreciated. The dealer gives me the runaround, where they say they're never heard of a G35 draining problem. Have asked several different people on separate occasions. I think they're trained to give that response.


I have an 05 G35 coupe, 5AT with about 110,000 miles, completely stock. It has the Bose audio, along with factory navigation. My car suffers from what appear to be MULTIPLE excessive parasitic draws, where if the car sits for more than 1 day, will not start. I'm on my 3rd battery since I bought the car 13 months ago. (The draining to empty and recharging kills them quickly). I used to drive it everyday, so it wasn't really an issue the first couple months. Now it's a problem.

After some research online, reading about other people with what seems to be a similar problem, I pulled the radio fuse for a couple days, and the car wasn't completely dead like usual, so I took the entire unit (radio, climate, GPS) to a local audio shop, where they rebuilt part of the radio circuit board, which from their tests, was the cause of a draw. Interestingly enough, while the entire radio unit was out, the car still drained (This was over a 10 day period). I simply figured it was because something was not shut off properly by the radio unit prior to removing it. Have tried disconnecting the amp in the trunk as well. No difference. (Radio repair is still under warranty.)

Car still drains, even with the repair. So I took my multimeter, and started pulling fuses to see what draws what. (Tested by connecting the multimeter between the neg. battery post and neg. wire) Basically, the car is drawing 0.480A when sitting. That will for sure drain a battery in no time. I removed every fuse under the hood (with the exception of the safety fuses connected to the + terminal.) Amperage dropped to 0.141A. I figured 141 milliamps is still too much, so I started pulling fuses by the pedals. Most drew negligible amounts (no more than 5 milliamps), so I put those back. The one that drew a significant amount was the trunk lamp+DTRL fuse. The trunk light, however is cold to the touch, so it's not staying on, even though that circuit is draining. The car doesn't have (but is wired) for daytime running lights. That seems to be drawing. I can hear a relay engage each time I connect the battery. When that fuse is removed, I don't hear it. So I removed that fuse. So the lowest I'm at is 0.017A, which I think seems reasonable. Now to reconnect everything:

(In order)
0.017A: LOWEST READING, MOSTLY EVERYTHING DISCONNECTED
0.141A: Trunk+DTRL fuse reconnected
0.208A: BCM fuse reconnected
0.370A: ABS fuse reconnected
0.480A: Radio fuse reconnected
(Radiator fans, rev. light diodes etc. not mentioned showed no change)

If you look at the differences between the circuits, the radio circuit is still drawing 110 milliamps, ABS is drawing 162 milliamps and the BCM draws only 67 milliamps, which is probably fine, considering everything it does while the car is off. The FSM does not give a range for allowable amperage draw. Why is the ABS system drawing nearly 3 times as much as the BCM? While off. And 110 milliamps to save my radio stations? I'll live without a trunk light, especially when that circuit draws 124 milliamps.

I also removed the alternator this past weekend to be tested, thinking maybe a bad diode was also partly responsible. Alternator tested fine.

My question is, what should the draw be (roughly) when this car is sitting off? If anyone would be willing to take an amp reading of their car simply by taking a multimeter and connecting it between the neg. post of the battery and the neg cable, I'd be grateful, just so I can get an idea of what I should be shooting for. Just a heads up, you would probably lose your radio stations because you're disconnecting the negative battery terminal, but it would really help me out. Haven't found a rough number online for this car, and I don't know anyone with this kind of car (or 350z), or I'd ask them to do it. Also, the reading will be higher for the first 10 seconds or so, because the audio system does a self-test of some sort. Assuming you don't have the same problem also! Thanks.

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500 mA might not be that bad.

if 500 mA will kill a battery in a days time then 115 mA would kill mine in a less than 5 days and I promise that isn't the case.
 

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Try leaving the meter in place for a while. My car had been setting for about an hour so and I didnt ever break the circuit putting the meter in.

some time to reset and/or settle might make a difference in the reading.
 

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Discussion Starter #6
Thanks for your replies, thatguy.
I left the meter connected for 15 minutes. Initially it starts off high because of the self-tests, but it drops to 0.450A and just stays there. I figured maybe some module might eventually go to sleep if I left it for 15 minutes or so, and would possibly drop the current draw. Made no difference. Also, out of curiosity, I disconnected the Bose amp in the trunk and tried the test again. Exactly the same result. I'm going to research the ABS circuit some more and see what could possibly be the culprit. I'm hoping not to have to spend a fortune on an ABS computer or anything along those lines.

A 450 milliamp draw kills the battery enough in a 24 hour period to (If I'm lucky) crank the engine extremely slowly. Over 2 days, and the starter won't even turn it.

In response to your second post, my car is drawing almost 4 times as much current as yours is. This is on a continuous basis. It's basically the equivalent of 4 of your cars being dependent on a single battery all day and all night while sitting. Without question, that battery will be spent within a day or two because 4 times as much current is being drawn nonstop. My Costco battery is rated at approximately 42 amp hours, so in its most efficient state (ideal conditions, and when new), it can sustain a draw of approximately 2.1A for 20 hours before the battery is completely useless at 10.5V. As time goes on, that amperage rating goes down. When the battery voltage reads anything less than 11.80V, the starter solenoid won't even engage. Interior lights will be very dim. I'm going to see how far disconnecting the trunk light +DTRL gets me. I'll test it with a fresh battery and see what things are like in a couple days. If anything here doesn't sound right, let me know. I'm by no means an expert at any of this.
 

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I understand the amp-hour rating system and that's what I'm getting at. my car should behave the same as yours but should take 4 times longer to do it. I know I've let mine set for a couple weeks in bad weather and it started up fine, considering last time I did that the battery was about 4 years old.
 

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I'll try to check my 01 Accord to see it's drain. it typically only runs a few times a summer and I don't think I've ever had to jump it. I think it's been about 2 weeks since it has ran and I bet it fires right up, even with a battery that's over 3 years old.

my point....

if it can set for 3 weeks and not kill the battery then based on your amp-hour like standard of 450 mA for 1 day; it has to have a draw of less than 20 mA and shouldn't be able to start after 3 weeks. I don't see that happening.
 

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my best explanation for your situation is an intermittent fault with the head unit. it is extremely common for the HU to crap out. I'm betting it weirds out and has a high current draw at some unpredictable point and completely kills your battery. from then on your battery is weak since it is not a deep cycle.

then maybe the 450 mA draw might be too much for it.


my 2¢
 

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Could it be a relay that is stuck like even for the ABS whereas it's keeping the juice going all the time? If so maybe try pulling one out at a time.
 

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So a few years later.. But I have a G37s with more or less the same problem. So I hope this thread can help me since the problem.
 

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So a few years later.. But I have a G37s with more or less the same problem. So I hope this thread can help me since the problem.
Sounds like a pain but you either try a DIY troubleshooting or pay for the service or fix. I remember looking this stuff up years ago on motorcycles which are (were) so darn simple. Yet even newer bikes have lots of additional circuitry etc...

Even with a car though, it seems to me a $35 multi-meter can allow you to do an 8 or 10 step procedure step-by-step and you ought to be able to pin down the correct sector by the fuse. If I recall correctly, you unhook the neg battery term then proceed to check current readings as outlined, eventually getting to a fuse that shows the higher than normal level draw. At that point, you've narrowed it to items within that fuse control. I'll guess it takes time and patience, but that's what you are paying for if you leave to someone else. The thing you want to hope for is that this is NOT and intermittent problem. IOW, anytime you put that meter on this test procedure, it always shows that unacceptable level of current draw. It'll be far easier and faster to track it down.

If this is something you want to undertake and don't find good info or links on the methods, let me know and I'll help you find them.

Secondly, if you have trouble getting a consistent reading that proves the parasitic draw, are you for certain the battery is good? I'read a lot of cases where time and effort were not spared but it turns out there was a bad battery or alternator. Start there at least to verify the charging system is doing it's job and the battery is A-1.
 

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Today I tried to narrow it down exactly by doing the above. Only the electrical wiring diagram is not easy to read. Also I'm not sure how long it takes before the CAN system is getting into sleep mode and I'm also not sure if it does matter if I leave the bonnet or door open. If yes then it is not easy to pull fuses.
Also I need a goal, I now have 230mA steady (that's after a few seconds, when I just connect it is 750mA). I think it's too much but what should it be like?
 

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Today I tried to narrow it down exactly by doing the above. Only the electrical wiring diagram is not easy to read. Also I'm not sure how long it takes before the CAN system is getting into sleep mode and I'm also not sure if it does matter if I leave the bonnet or door open. If yes then it is not easy to pull fuses.
Also I need a goal, I now have 230mA steady (that's after a few seconds, when I just connect it is 750mA). I think it's too much but what should it be like?
This is what THATGUY came up with.... not sure if newer cars with more goodies means more current draw though.

05 6MT.

car off, 115mA.

didn't even lose the radio presets.....I have tricks.....
 

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I'm posting 2 links here and 95 % of this info may be 'old hat' but the two agree on a range of acceptable milliamps draw for newer cars.

The one site revisits the simple how to for testing and Randy's Repair has some good insights, tips and tricks for testing. I'll highlight a few items from Randy's and leave the links for your access/perusal.

This part here has me thinking the actual draw one reads might be created by waking up the system without knowing it.... See blue text-

Computers That Must Time Out

By the mid 1990s many manufacturers had at least one computer that would draw as much as three amps for up to 20 minutes after turning off the ignition switch before it went to "sleep mode". These systems present new challenges when measuring current drain because anything that creates an open circuit and removes battery voltage will wake those computers up again for another 20 minutes. You must insert the ammeter as shown in Figure 1 on a high enough range to prevent blowing an internal fuse in the meter. After the computers have timed out and current drain is ready to be measured, you must switch the meter to a lower range for the needed accuracy. Switching to a lower range is the problem. Most digital meters require one lead to be plugged into a special jack for the 10 Amp scale, then it must be moved back to the common jack for all the other ranges. Removing the lead breaks the circuit. When the meter lead is plugged in again, the computers will again draw high current until they time out.


By the early 1990s, many more computers were showing up and most of them had their own memory circuits. Body computers add a new level of complexity to many systems. Air bag, anti-lock brake, and transmission computers all draw memory current. Unless the manufacturer specifies differently, the industry standard is a maximum of 35 milliamps allowed to maintain all the computer memories. At that rate, a good battery will crank the engine sufficiently for starting after sitting for three weeks. A few manufacturers allow 50 milliamps.

http://randysrepairshop.net/testing-for-battery-drain.html

http://www.wikihow.com/Find-a-Parasitic-Battery-Drain
 

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Just for somebody else with the same problem.
Recently i've solved the battery drain problem. It was solved by removing the terrible built in Viper alarm system. The alarm caused the CAN-bus system didn't went in sleep mode. If the system is not in sleep mode it consumes about 250mA, when it is in sleep mode is goes to 30mA.

It was a viper alarm with remote start. But there was an auxiliary module which was really terrible built (see attached pictures). It took me two days but everything went well.
 

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Congrats Robert ... Well done !!
I assume that alarm system is aftermarket add-on ?


If so, I guess I learned that the first question to ask on anything similar is; "Do you know if the car has any add on or DIY installations? If so, isolate those systems one at a time."

I can see how even a simple seeming audio system with switchable amp could be faulty or hooked up wrong and do the same type of thing and there is no telling how many other doo-dads people put on cars these days..... rear facing camera, front facing recording device, radar detectors, Nav and custom sound systems, aux or custom lighting, alarms systems/remote start, blue tooth .....

One thing I did tonight and think of a few times a year is using my battery tender style maintainer from my motorbike with alligator clips and just randomly (now and then) hooking it to one of my car batteries overnight. I figure a little boost now and then can't hurt and I have it on the G35 tonight plugged in here at work.

I typically think to kill the fan from high blower if it's on and the heated seat switch if using them before shutting off either car. I figure anything that is extra draw on the system is just more stress when starting the car as it turns over.

Maybe as I get older, I'm just getting as crazy as I used to think my grandparents were in those days when they thought they better unplug the VCR at home if they were going away for a few days (in case it burns the house down) .... lol

Now, I understand technology can be a bit intimidating but this was the 1970's and TV's and so many other electronic gadgets were around for years and years and they never unplugged the toaster, the blender, the washer and dryer etc...... Nope, just the one time that had the clock on it and it blinked constantly because they never knew how to reset it.
But I guess maybe that's why we went to visit the grandparents so often. so we could reset their *&^% VCR clock !!

:rolleyes:
 

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That's the worst circuit I've ever seen. I'm surprised it worked enough to complete a circuit.
 

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2007 Infiniti G35S parasitic draw reads 0.13 Amps with all fuses connected. Removed all fuses individually, only 1 had any effect. Removing the 10A fuse labeled "ROOM LAMP", reduced the parasitic draw from the above stated 0.13 to 0.07-0.08 Amps. I believe the 0.07-08 Amps to be the "factory OEM normal condition"; however, that is conjecture on my part given what Ive read on various sites.
 
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