HowTo: Disable ECM Controlled Alternator

[VStar650CL]

Here's how I do the job quickly, neatly, and undetectably unless you know what you're looking for. The subject vehicle is a '16 QX80, but the same technique will work fine on just about anything with a PWM-controlled alternator. For the most part the Armada/QX80 connector can be gotten out without moving the IPDM, but you may need a hook tool to depress the tab enough to get the connector to move. Some of them can be very stubborn.

On the QX's and Armadas there are always two red wires in the connector, the right one (all Red, green arrow) and the wrong one (Red with a White tracer, red arrow). If you clip the wrong one your car will no-start.

Start by clipping the correct wire, then bend the cut end on one side back on itself. Insert it into a solder shrink tube and shrink that end over the wire without melting the solder. That seals the end so it's weather-tight and can never make contact.

Then repeat the same thing on the other cut end. If you're using a Bic for shrinking as I do, keep the tube in the blue part of the flame and you won't get a lot of carbon-crud on the work.

The shrink tube will have the effect of compensating for the bent-back wires, so your finished product will be almost the same length as the uncut wire. Just tape it up neatly and it will almost unnoticeable.

If you've done it correctly, you'll have a happy alternator which outputs full rated regulation voltage at all times.

[Jreeves45]

Is this the same for 2015 qx80? Mine was fine yesterday but today nothing. Won't start even when attempting to jump it. No electrical at all as though the smart key is dead. Replaced batteries in both fobs. I have no idea what to check to get it started.

[VStar650CL]

No power even with a jumpstart almost always means a bad battery lug or bad cable. It's remotely possible for a completely dead battery (so dead it's sucking down the jumpstarting voltage) to cause it, but that's very unusual. The battery has to be in a very narrow range around 8V for that to happen, below that the battery will resist a charge and won't resist jumping. Have a close look at your battery terminals and cables, it's likely your problem is there.

[Brian35XR]

To toss another anecdotal report in: I did this mod at the beginning of this year, 2024, along with buying a brand new battery (because the old one was dead from being discharged in the Winter so many times - 3rd new battery for this car).

For the past 2 weeks my Brake+Battery light would pop on and off intermittently but stay off for the majority of the ride. These lights are common for Japanese cars when there is a fault somewhere in the charging system. Last week the lights stayed on the whole ride, and as I was getting on the highway my car went into "Limp mode" and would no longer give gas from the accelerator pedal (but no other lights came on). I had to call for a tow on a highway where there is no shoulder with speeding cars zooming past. Side-note: Screw Progressive, Screw AAA - they never come and say oh just pay for a tow and submit reimbursement online, then when you submit reimbursement they say the receipt is rejected for not being in the format they want - scammers.

Anyway I got the car home and it did start up and drive, I'm assuming after the alternator cooled down. Today (1 week later) I took the battery upstairs, it only read 2.5v on the multimeter.. That's TWO point five. I un-did the hack just in case and re-inserted the Brown 22-PIN on the specific harness of the IPDM. In the meantime I have the battery on my charger in "Low Voltage Repair Mode" - it's currently halfway done and reading around ~13.3v on the charger. I hope the alternator is fine.

My only assumptions are either 1. The battery was defective from the start (which I doubt) and couldn't hold a charge which overheated the alternator and put it in Limp Mode or 2. The hack forced the alternator to overcharge/kill the battery in 6 months which caused the alternator to overheat when it couldn't hold a charge. Hard to believe that as well because even though there are reports in the thread of similar things happening to others, most people report no issues. Any thoughts from the Nissan guru and others?

[VStar650CL]

The only way a battery overheats an alternator is if it's sucking more current than the alternator can source. The internal regulation is self-limiting under any other circumstances, because the alternator will only source exactly enough current to maintain the fixed charge voltage. You'd be amazed at some of the crap we see these days in the way of batteries, so I wouldn't be a bit surprised if your new battery got a collapsed-and-shorted cell. Unless you're running a kilowatt of woofer in your cargo room, that's about the only thing which can overload an alternator the way you describe. It's also possible the regulator failed and melted the battery, but that's a chicken-and-egg thing that you'll probably never know. Regulators do fail (although they usually fail open and not short).

[Grendeleve]

Hi all, sorry if bumping an old thread. I have been down this rabbit hole for so long and landed here.

2011 Infiniti FX 35, recently got it from a family member, they maintained it mostly as infiniti dealership, normal behavior in summer , never had any issues, come winter in Canada i start seeing the battery sign on dashboard on cold mornings, after a bit of driving used to go away. So I ignored, until one day i got stranded . Well, i thought it must be the battery, could not remember when it was replaced. ok no prob, get a new one from Costco, all well for a while and the same issue keeps happening and more severely.

Decided to look into it more, plugged a scan tool and measured voltage at ON, 11.5V start car and it kept the voltage same, no charging, start driving for a while and keep an eye on voltage. Fluctuates between as low as 10.5 to 11.5 at most even while driving on highway. Made a turn to head back and car starts loosing power, pull on the side and maybe it must have hit the certain distance by then but the alternator suddenly started outputting at 13-14.5V and rest of the drive was great.

More research and found all this variable charge non sense. currently debating taking to dealership and asking them to disable this feature or trying to unplug the battery current sensor. Can anyone who has also done this please share their experience.

Also @VStar650CL may I please ask if you could guide me what pin/cable would it be on my case.

Thank you so much.

[VStar650CL]

I doubt 10~11V is from the dumb charge, that sounds more like a bad alternator. But you can try snipping the PWM wire, it can't hurt. I'll get you specifics in the morning, ASIST seems to be acting up right now.

[Yoda's Master]

After you snip the wire, you need to change the battery since the bad charging probably damaged it already.

[Grendeleve]

Oh you think it is just a bad alternator? But how come after driving a certain distance it will start putting upward of 13V with no further drops? Very strange. Most of my daily commute are just 4-5 kms.

I will look into getting alternator tested first too.

[Grendeleve]

After you snip the wire, you need to change the battery since the bad charging probably damaged it already.

The battery was replaced three weeks ago. But I will keep that in mind

[VStar650CL]

Okay, your'11 FX has the old style IPDM with the long latch connectors. The PWM wire is on pin 76, it's Violet if you have the VQ35, Pink if you have the VK56.

[Yoda's Master]

After you snip the wire, you need to change the battery since the bad charging probably damaged it already.

The battery was replaced three weeks ago. But I will keep that in mind

Just take it back to Costco and them them it died. You're not going to notice the change if the battery is damaged and that usually happens around 10 volts.

[VStar650CL]

Oh you think it is just a bad alternator? But how come after driving a certain distance it will start putting upward of 13V with no further drops? Very strange. Most of my daily commute are just 4-5 kms.

The regulator is a silicon part. It's very common for them to overheat and go in-and-out when they're failing. Since the regulator also drives the lamp, it's also not uncommon for that to happen with no warning lamp.

[Grendeleve]

Okay, your'11 FX has the old style IPDM with the long latch connectors. The PWM wire is on pin 76, it's Violet if you have the VQ35, Pink if you have the VK56.


11 FX Alt Mod.jpg

Thank you so much, i will try and get this a go. -10 C here haha so no fun.

Today morning on my drive to work (2.5 KM) i kept an eye on the voltage using a plug in OBD2 tool, it may not be the most accurate but it shows a picture. I kept the AC and Rear Defrost ON to put load along with fan on high and seat heaters ON, they never got hot lmao.(not enough power)

Started the car to ON position 11.52V A bit low but nothing crazy, should charge ideally but it's -10C outside for the last week
Start the car and let it idle for 1-2 mins 11.36V
Start driving 11.12V
Throughout the drive the voltage goes as follows, 11.04V , 10.96V , 10.88V , 10.56V
Reach work and end the drive with similar 10-11V

Net battery never went higher than what started. This seems to me that the whole time there was 0 attempt to charge the battery. This is strange since just 2 days ago while going on a longer drive the alternator eventually did kick in and kept it above 13V the whole time. The battery and Brake light were ON the whole drive. For those who have experienced this smart charge issue does this seem similar? The results might be exaggerated but maybe due to how cold it is outside. I was able to find the battery current sensor but could not get to unpluggin it, will try it later today.

[Grendeleve]

The battery was replaced three weeks ago. But I will keep that in mind

Just take it back to Costco and them them it died. You're not going to notice the change if the battery is damaged and that usually happens around 10 volts.

fair point, i will try doing that this weekend as well.

[VStar650CL]

The battery and Brake light were ON the whole drive.

If the generator light was on then the problem is definitely the alternator itself and not the dumb charge. The only thing it could be besides the alternator is a bad connection to the field fuse. Unfortunately, the only good way to check that is to back-probe the connector at the alternator to see if there's 12V getting to the field. The wire will be Violet for a VQ or Orange for a VK and should be hot at all times (fused to battery). That said, unless the alternator connector is trashed (which can happen with old age), it's about 99% probable you just have a bad alternator.

[Grendeleve]

The battery and Brake light were ON the whole drive.

If the generator light was on then the problem is definitely the alternator itself and not the dumb charge. The only thing it could be besides the alternator is a bad connection to the field fuse. Unfortunately, the only good way to check that is to back-probe the connector at the alternator to see if there's 12V getting to the field. The wire will be Violet for a VQ or Orange for a VK and should be hot at all times (fused to battery). That said, unless the alternator connector is trashed (which can happen with old age), it's about 99% probable you just have a bad alternator.

Thanks for your insight, greatly appreciated. I will book a visit to dealership and see if they can confirm your point. If that is the case then i should just look towards getting a new alternator. Any tips on replacement? I see lot of people online having issues when the use remanufactured. Should i go for a new one?

[VStar650CL]

New is usually the way to go, yes (if available). Many "remanufacturers" just test the regulator and don't replace it out of hand. That means units like yours which are going in-and-out can slip through the cracks and end up being the next person's headache. Given how difficult most Nissan alternators are to change, you probably don't want to be that guy.

You also don't want to take a chance that the regulator will be behaving itself when you go to the dealer and they tell you they can't find anything wrong. Make sure the gen lamp is lit in the service drive and show it to the advisor.

[Grendeleve]

New is usually the way to go, yes (if available). Many "remanufacturers" just test the regulator and don't replace it out of hand. That means units like yours which are going in-and-out can slip through the cracks and end up being the next person's headache. Given how difficult most Nissan alternators are to change, you probably don't want to be that guy.

You also don't want to take a chance that the regulator will be behaving itself when you go to the dealer and they tell you they can't find anything wrong. Make sure the gen lamp is lit in the service drive and show it to the advisor.

Thank you. I booked an appt with my dealership this 8th, will have them take a look and confirm if its alternator, Will take a pic of battery light to show them as well. Asides from a possible new alternator and a new replacement costco battery i'm planning on asking them to clip the wire too to prevent any future issues. You all have been very helpful and i will update you guys on what happens

[Grendeleve]

To toss another anecdotal report in: I did this mod at the beginning of this year, 2024, along with buying a brand new battery (because the old one was dead from being discharged in the Winter so many times - 3rd new battery for this car).

For the past 2 weeks my Brake+Battery light would pop on and off intermittently but stay off for the majority of the ride. These lights are common for Japanese cars when there is a fault somewhere in the charging system. Last week the lights stayed on the whole ride, and as I was getting on the highway my car went into "Limp mode" and would no longer give gas from the accelerator pedal (but no other lights came on). I had to call for a tow on a highway where there is no shoulder with speeding cars zooming past. Side-note: Screw Progressive, Screw AAA - they never come and say oh just pay for a tow and submit reimbursement online, then when you submit reimbursement they say the receipt is rejected for not being in the format they want - scammers.

Anyway I got the car home and it did start up and drive, I'm assuming after the alternator cooled down. Today (1 week later) I took the battery upstairs, it only read 2.5v on the multimeter.. That's TWO point five. I un-did the hack just in case and re-inserted the Brown 22-PIN on the specific harness of the IPDM. In the meantime I have the battery on my charger in "Low Voltage Repair Mode" - it's currently halfway done and reading around ~13.3v on the charger. I hope the alternator is fine.

My only assumptions are either 1. The battery was defective from the start (which I doubt) and couldn't hold a charge which overheated the alternator and put it in Limp Mode or 2. The hack forced the alternator to overcharge/kill the battery in 6 months which caused the alternator to overheat when it couldn't hold a charge. Hard to believe that as well because even though there are reports in the thread of similar things happening to others, most people report no issues. Any thoughts from the Nissan guru and others?

Hey Brian did you ever figure out what cause this for you? similar experience, i'm getting my alternator checked in coming days.

[VStar650CL]

i'm planning on asking them to clip the wire too to prevent any future issues.

They probably won't do it for you and may try to sell you a Current Sensor. Nissan engineering approves (strictly in a backdoor way) of performing the mod on Armadas and QX80's for the model years with PWM alternators. To my knowledge they don't approve of it on any others. If you want it done you'll probably need to DIY it.

[Grendeleve]

i'm planning on asking them to clip the wire too to prevent any future issues.

They probably won't do it for you and may try to sell you a Current Sensor. Nissan engineering approves (strictly in a backdoor way) of performing the mod on Armadas and QX80's for the model years with PWM alternators. To my knowledge they don't approve of it on any others. If you want it done you'll probably need to DIY it.

Will keep that in mind, went into limp mode again today going back home, restarted and turned on fine and all of a sudden constant 13-14V being generated,,, so yeah the alternator is indeed behaving oddly.

[Grendeleve]

The battery and Brake light were ON the whole drive.

If the generator light was on then the problem is definitely the alternator itself and not the dumb charge. The only thing it could be besides the alternator is a bad connection to the field fuse. Unfortunately, the only good way to check that is to back-probe the connector at the alternator to see if there's 12V getting to the field. The wire will be Violet for a VQ or Orange for a VK and should be hot at all times (fused to battery). That said, unless the alternator connector is trashed (which can happen with old age), it's about 99% probable you just have a bad alternator.

VStar you were absolutely right haha. It was a bad alternator, ended up going to a local mechanic instead. Once everything changed it turns out smart-dumb charge may not be the issue. When cold starting the car, the voltage immediately jumps to 14V and stays there for the drive even if i have NOT YET driven 12 kms(8mile) for the day. I will keep monitoring this and if it trips again then i will clip the wire as you showed in diagram.
The mechanic installed i believe denso rebuilt, i should have asked for a new one but with work i didn't get a chance and he has installed it by then, hope it stays working for a while.

Thanks again for your help.

[VStar650CL]

[Espious]

So, I wasn't having the battery charging issue. I cut the wire anyway and it seems to have fixed my wonky idle.

Still having issues with all lights pulsing (reverse, dash, interior lights, fog lights, etc) so I assume the alternator needs replaced. I'm happy that I can at least put that job off for a bit longer though.

[2015roguesl]

Hi
I have a 2018 Nissan Rogue SV
Any info on HowTo: Disable ECM Controlled Alternator for the Rogue, photo of wire to cut?
And
I was thinking putting in a switch instead of just cutting wire, and wondered if the dash lights would go out when switch was closed verse being open, so i could have full charging and smart charging.

Thanks

[VStar650CL]

You can't disable it on a gen2 Rogue, it uses a LIN alternator instead of PWM. The grille shutter is on the same LIN circuit, so you'll get a full-blown Christmas tree on the dash if you cut any wires. The only thing you can do is yank and tape-off the connector for the Battery Current Sensor, located on the negative battery lug. That will limit the smart charge functionality but shouldn't light the MIL.