My infiniti Q45 has suddenly started draining the battery overnight. I had the alternator and battery tested. Both were fine.Also, the alternator tensioner pulley jammed up recently and had to be replaced.

The Traction lights come on after driving for alittle while, and there is a buzzing noise that comes from the car about every 5 seconds.

Any ideas on what is going on?

put an ammeter on the battery and start pulling fuses one by one to see whats causing the drain.

Welcome to NICO!!

most likley its coming from the TCS, could either be a relay or the actuator?

The exact same thing happened to me last night!

On Sunday, we took a couple of short (1.5 hours each way) highway drives. It was hot, so we had the air conditioner running near full blast on the way back.

Come to think of it though, on the return trip, acceleration got a little less perky during the final 30 minutes.

Anyhow, this morning, the battery was almost completely dead. For some reason, the air conditioner display was blinking on and off while making a slight clicking sound. I assume that this is just some sort of "Hey, you're battery is dead" kind of signal.

I plugged in my batter charger and it drew max for the first 10 minutes and then settled in at 7-8 amps.

Any suggestions - other than the fuse-pulling spree?

Could be something as small as the the knob to the left of the main gauge cluster that has the light bulb on it. Try turning that to the middle. Mine was turned to side and was killing my battery. Also check to see if there is grinding noise in your engine compartment when you park and cut the car off. If so, that could be your ABS relay back by the firewall. Just tap on it a few times, and it should cut off. Good Luck!

-Evan

Here is a quote from an old post I did regarding amperage draws under various conditions on my '94 Q45. It should give you a good idea of where your car should be if it was not draining the battery. If you have more than about .05-.07 amps draw from your battery with everything off after a couple of minutes there is something draining the battery so start pulling fuses for various circuits to narrow it down. I give several examples in my testing on what to disconnect and it's effect.

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OK, I have some baseline numbers from my '94 that's currently great in the electrical department. I pulled the negative terminal and installed my Fluke ammeter inline. Leads in the 10 amp terminals on the meter. You could use the positive as well, would make no difference. I just used the negative as it doesn't have all the other wires connected to it. Negative meter lead to B- and the meter positive lead to the negative battery cable. If you get these backwards you will just read negative amps, no big deal.

Upon connection the dome turned on and stayed on due to my aftermarket alarm until I armed and disarmed it. Then it turned off. Also, there are apparently some systems that operate for a couple minutes upon connection of power as the amps take about 1-2 minutes to stabilize at the low level.

Initial connection w/alarm disarmed, dome light on -> 3 amps, settled to 2.6 amps

Aftermarket alarm armed, dome light off -> .24 amps then settled to .066 amps after approx. 1 minute.

Alarm disarmed, dome light off -> .063 amps after 1 minute

Start pulling large fuses in under hood fuse compartment, unless noted I reinstalled the fuses prior to pulling the next fuse/relay"IGN SW" 30A fuse -> .056 amps"ENG CONT" 25A fuse -> no change"INJ" 25A fuse -> no change"COND FAN" 30A fuse -> no change"MAIN" 75A fuse -> .043 amps"MAIN" and "IGN SW" -> .035 amps*When "MAIN" reinstalled amps were at .5 amps 2 minutes then settled back to .063 indicating that a circuit was operating for a couple minutes upon power up, ECU?"Power window" fuse -> no change"Anti Skid" fuse -> no change"Blower Motor" -> no change

Small underhood fuses"Eng Cont" 10A fuse -> no change"Fog Lamp" 15A fuse -> no change"Room Lamp" 10A fuse -> no change (unless the dome light was on already)"Tail Lamp" 10A fuse -> no change"ALT (S)" 10A fuse -> no change"Hazard" 10A fuse -> no change"Horn" 15A fuse -> no change"Headlamp LH" fuse -> no change"Headlamp RH" fuse -> no change

Relays underhood in junction box (same box as above)"Anti Theft" -> no change"Cond Fan" -> no change"Cruise Cont" -> no change"Inhibit" -> no change"A/C" -> no change

MiscellaneousTrunk open w/trunk lamp on -> .4 amps (amps fluctuating +/-)Room lamp fuse out, door open -> .233 amps (might be alarm LED drawing)Room lamp fuse out, door open, park lights on -> 6.2 ampsHeadlights on -> Exceeded 10 amps, couldn't get accurate reading

This should give you a good start on tracing the amp draw. I didn't pull the two really large fuses next to the fuse/relay box (100A+) or the two black/white wires plugged in at the B+ terminal.[QUOTE=EQwhipD]Could be something as small as the the knob to the left of the main gauge cluster that has the light bulb on it. Try turning that to the middle. Mine was turned to side and was killing my battery. Also check to see if there is grinding noise in your engine compartment when you park and cut the car off. If so, that could be your ABS relay back by the firewall. Just tap on it a few times, and it should cut off. Good Luck![QUOTE=EQwhipD]Could be something as small as the the knob to the left of the main gauge cluster that has the light bulb on it. Try turning that to the middle. Mine was turned to side and was killing my battery. Also check to see if there is grinding noise in your engine compartment when you park and cut the car off. If so, that could be your ABS relay back by the firewall. Just tap on it a few times, and it should cut off. Good Luck!

Just wanted to close the loop on this on.

I had my fuse-pulling party on Monday morning. Unfortunately, I don't have a nice ammeter but I do have a cheapo battery charger and it has a simple analog ammeter. Not precise but good enough for some quick tests. I let the battery charger run while I pulled fuses and watched the needle.

Generally, there were no perceptible movements of the needle when I pulled each fuse ... except for one. It was the dome light, registering perhaps half an amp.

To make a long story short, the passenger door was ajar all night and that must have drained the battery. Through recharging, I've confirmed that the battery will hold a charge and through driving I've confirmed that the alternator is charging the battery (that is, the amps aren't pretty much holding steady after a drive).

That dome light must be one power-hungry son of a gun!

You know, most cars nowadays have lights-on warnings (my 86 Camry would turn them off when I opened the door, not so my 94 Q45) but wouldn't it be nice to have some kind of battery-drain warning? Maybe at a future auto show?

ha haa yeah i killed my old battery by leaving the trunk ajar all night. As you know, if you pop the trunk but dont go open it, theres not much gap there so you can easilly walk away without noticing the trunk is popped. Of course the light will be on... will kill an old battery overnight. Ooops. I think every driver in the world has drained a batt overnight, admit it or not.

1996 Q45 95,000 miles

This is my second run at a battery drain problem. Thanks to qsiguy for the above info. I think I may have more than one issue. I'll try and briefly describe the known info.

If I take out the power window breaker (25A) my drain goes from about .2 amps down to .09 amps. I think this is my major issue. Removing this breaker also allows my security system to arm which it has not worked since I bought the car 3 years ago.

The above pointed me to the self diag tests in the EL section of the FSM. Mode one of the on board diagnostics gives me an error 21. Which indicates LCU01 -A both data line communication failure. Is this a total failure of the BCM or is LCU 01 -a just a sub module? Thanks in advance.

the LCM is the little computers that are in the doors (and for that matter, spread out throughout the car).

I dont know off hand which one LCU01 is but replace that one...

Yes, it is in the driver's door. I'm trying to find the part number in the FSM so I can see if it is the same as other years. I'd like to find a used one if possible. I suspect the driver's door is different since it looks like it controls the memory settings for the seats et al.

I pulled it up in the parts book and Im seeing that all the LCU's from build date 0293 + are compatible. I only see one number for the LCU on the drivers side (Sometimes called power window amplifier).

Thanks for checking Wes. I'll email Joe and see what a new one costs.