long story but answers a few questions that nissan can't.
I spent hours on the phone with nissan local and nissan north America with their answers to questions limited to -we can't- they can't-it won't-uh huh- and so sorry- then I got into the books and tools.
As we all know, the Armadas leak voltage like water through a sieve. I have been attempting to train the local stealership about the charging system. First problem identified is that Nissan has not updated their maintenance computer system for the Armada since 2006. Their current maintenance, parts, and service computers show a revision date of 2012 but contain all the 2006 images. So if you are looking for a current electrical system diagram for the Armada, don't bother looking for it, it's not there. However, the Titan crowd has found a way to apply leverage and most of the updated diagrams, to include the IPDM for the 2007-2010 Armada are on the Titan service system.
That being said, I went to replace the ECM relay on my 07's IPDM. Checked with Nissan Parts, Service, and Mechanics computer systems, got the diagram and the relay, per their instruction- only problem is the 2007-2010 has no ECM relay on the IPDM... It's included in the IPDM. The voltage regulator that we old farts all knew and loved, because it was easy to understand, manipulate, repair, adjust, is now included in the IPDM of 2010-2010. It's results go to the ECU which then controls the alternator output.
Reason this is interesting. The charging system is based on some really odd really old designs with modern adaptations. The ECU, which controls the charging rate, voltage, and amps, receives it's information from the IC regulator/electrical feedback sensor (the circular thing on the negative battery cable located about 6" down the line from the battery terminal.) it's the size of a 5 peso coin. Basically, it's a magnetic field sensor the exact same as what you run over at a stop light. The signal generated tells the ECU to tell the alternator how much and how hard to charge, ostensibly so that the alternator doesn't constantly charge, in order to save gas. But the field sensor/ic regulator/ feedback sensor routes through the IPDM. So here's what we start with.
You have basic battery voltage that isn't measured, but is indicated. You have basic battery amperage available, which isn't measured. Then you have running car voltage which is measured and compared to a reference voltage programmed into the IPDM and the ECU which sounds normal. But the reference voltage is programmed in as 12.1 volts (read from the OBDII port) So first problem is, the battery is fully charged anywhere from 12.4 volts for a factory new nissan overpriced lead acid battery to 13.2 volts for a top of the line AGM battery. So your charging system will never fully charge your battery. Next, with a battery of 13.2 volts, and OBDII port voltage indicated as 12.2 volts, and a dash gauge indication of 11.2 volts, you have three different inputs going to the IPDM and the ECU. Computers can't handle conflict. Now remember the voltage leaks we all have?
Well they come into play after the battery reference voltage of 12.1 comes into play. So the gauge may say you have 12.2 volts available, which is one needles width below center/half scale on the dash gauge, but you may only have 11.2 at the battery. 11.2 will generate all sorts of flashing dash lights, anti lock problems, transmission shifting problems, 4whl drive selector problems, traction control problems, etc.
If you have low voltage but have a system that doesn't leak voltage too badly or have an alternator that starts charging immediately, you should see a dash voltage needle position 1/8" to the right of center instantly after start up. If the charge catches up with the system before the system reacts to the low voltage, you may not know you have a problem.
The center line position on the dash voltage gauge is 13 volts. You should always see a voltage indication to the right of the center line. When you turn the car on, but don't start it, you should see a voltage indication with the needle on the dash gauge no more than one needle width to the left of center. If you have a super AGM battery, resting voltage will be with the needle touching the centerline on the gauge. So, we have an ECU and IDPM with all slots that can be programmed, programmed in with a 100% charge/voltage reference of 12.1. Nissan has no way of measuring or determining any of these parameters at the dealership level maintenance facilities. Of course, you also have to remember that Nissan has no maintenance facilities anywhere in the U.S. the maintenance facilities at the dealership are sub sub contracted companies who supply nissan with trained mechanics. Therein lies another problem. None of the nissan trained mechanics anywhere are taught how to repair the vehicle. They are simply taught how to swap parts. They have no diagnostic capability for anything. They have trouble shooting checklists that say if the car does X check Y, if Y isn't at X level, replace part Z. So if you have CV joints that are all clunking and can be moved by hand, nissan considers them to be OK and will not replace them until they physically break apart. If you have bad universals, they won't replace the universals, they replace the whole driveshaft unit. If your charging system is faulty or the factory programming in the IPDM or ECU is bad, they only know to swap parts and not fix anything.
So if your charging system needles swings correctly but doesn't charge your battery to the correct level. If your OBDII port shows a voltage one or two volts down from what the battery actually has. And everything appears to work correctly but not produce the desired results (fully charged battery) (no flashing dash lights) (correctly working antilock and traction control systems) then you have to figure a way to lie to the charging system to make it think it needs to do more, in order to get the correct results.
The IC regulator is temperature sensitive as cold makes wire flow voltage better, hot slows voltage down/decreases it. The connector into the sensor has three wires which are crimped and not soldered, then plugged together. Soldered or solid continuous wire is impervious to water, vibration, dust, temperature, etc. Crimps are not. Nissan has no way of diagnosing or checking the IC regulator/voltage feedback sensor. If you say it's bad, nissan can only replace the whole negative battery cable instead of replacing the 5 cent sensor loop. So- how do we get around this?
Fool the sensor! Take the tie wrap off the sensor, slide the sensor (black plastic circular thing with a plug on the bottom/side/back containing three wires that runs into a wire tube, then back to the IPDM) out of the way, take a piece of tin foil 4" x 5"wide and wrap it around the negative battery cable, centered where you will move the sensor back to when finished. Once you have the tin foil wrapped, cover it with a layer of electrical tape, one piece thick. Slide the sensor back to center over the tin foil and re-tie wrap it in place. It will now shield the negative battery cable and make the sensor think that it's reading less voltage than actual and tell the system to raise the minimal acceptable charge level to - in my case 13.4 volts- up from 12.1. More tin foil, higher charge levels, higher battery voltage. So far, 28 degrees up to 80 degrees no longer affects the output. Hours on the freeway at 80 degrees or hours on the freeway at 29 degrees make no difference. The click and return to zero charge is gone. And if I let the car sit a week, when it starts, it immediately charges at 14.2 volts, dropping as the battery re-energizes stopping at a charge level of 13.9 when cold or 13.4 when hot.
On my AGM 13.2 volt battery, resting voltage has gone from 12.2 volts (11.1 volts on a new nissan battery) before the fix up to 12.9-13.2 volts after the fix.-where it's supposed to be- It's cheap, easy, and allows you to manipulate the voltage as you watch so you can check the rest of the systems performance as well.
