Need some help peoples .. I have had the dreaded battery drain ever since I bought my G ... Had the TSB done and still issues . I don't drive my G much and when I do it's short distances ... I found out on the M forums that the ECM turns on the alternator after 8 miles of driving .. The M guys are having battery issues as well .. I verified through Infiniti that the ECM does in fact activates the alternator after 8 miles .. What the M guys are doing is disconnecting the ECM wire that controls the alternator from the IPDM . When they do that the alternator turns on the moment u start your car and stays on until u shut the car off .. So it is always charging the battery . The M guys say it works and I need to know where where the ECM wire to the IPDM is so I can disconnect it ... Please let me know ...

Thanks !!!

 

Im confused.....where the does the output of the alternator go when its not "activated"?

Is driven by a belt that is spinning whenever the engine is running, AFAIK. Or is there some sort of clutch that gets engaged to it?

 

I would like to know an answer as well. I was reading the topic for the M's. I drive short distances too

 

Im reading the thread too and it still makes no sense to me.....the "reasoning" was to save MPG? The only thing that makes sense is there is a clutch built into the alternator (much like your A/C compressor) that only engages when the ECU tells it to. Without a clutch disengaging the pulley, you couldnt save any mpg by having the alternator "off"

Is that the case? Ive never looked at the alternator with the engine running, so I dont know.

 

I actually did this mod and my alternator turns on the moment I start my car .. Thank goodness I found that thread . I did the same thing that Infiniti techs are doing for the m guys ... I could post a DIY with pics I Took . If you are having battery issues give it a try . I will report back in a couple of weeks ..

 

Please post a DIY.

Please include exactly what you use to determine your alternator is "on" or "off" because thats the part of this I cant wrap my head around.

 

I've never heard of an alternator being switched on or off.
Has anyone confirmed this in the M FSM?
The easiest way to prove this switching the alternator on or off does not occur would be to place a voltmeter across the battery with the engine off.
A fully charged battery will read 12.6 volts as each of the 6 cells in a 12 volt battery are 2.2.volts
Start the vehicle and then observe the voltmeter reading.
Normal alternator output is 14.4 volts.
If you observe that reading then the alternator begins charging the battery immediately upon startup.

Telcoman

 

It might actually be true.....

Check the FSM in the G37 sedan forum....CHG.pdf, page CHG-6 thru CHG-9

"IPDM E/R converts the received power generation command val-
ue into the power generation command signal (PWM signal) and
sends it to the IC voltage regulator."

"IC voltage regulator controls the power generation voltage by the
target power generation voltage based on the received power gen-
eration command signal.
When there is no power generation command signal, the alterna-
tor performs the normal power generation according to the char-
acteristic of the IC voltage regulator."

 

Talking out loud, but Im wondering if this is also helping cause the DAS issues on the Q50

People complained the issue would show up after a short trip, run into the store run right back out kind of thing.....

 

I'd be interested in a DIY write up on this

 

From what I see in the factory service manual, there should be 4 terminals connecting to the alternator.

The "C" terminal looks to be the one that controls the variable voltage generation system. From the sounds of it, the dealer just disconnects the wire to that terminal (I dont know if its a single terminal that bolts on or if its part of a harness connector).

Once that terminal has no signal, the variable voltage generation is no longer variable.

 

Also I was wondering, is it really "8 miles" or is it supposed to be "8 minutes". It seems odd that the alternator would be set to start charger after 8 miles. If that were the case if you were just warming up your car theoretically you would drain your batter since the car is not moving the pre-requisite "8 miles". Just a thought.

 

It's the yellow wire in your ipdm which is in your engine bay

 

According to the Infiniti tech it turns on after 8 miles . The reasoning is to save gas .. I would rather have a charged battery ..

 

So what cable to we need to disconnect on the alternator??