Battery not charging after alternator replacement

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Xabyte
Posts: 2
Joined: Tue May 03, 2022 12:09 pm
Car: 2008 Infiniti G35/37 4Dr Sedan Base

Battery not charging after alternator replacement

Postby Xabyte » Wed Aug 17, 2022 8:15 pm

Greets everyone,
I hope I can get some valid information here on the issue I'm having. I own a 2008 G35 Infiniti Sedan. I've had the car nearly 2 years. The alternator went out about a year ago. I had it replaced and the car ran fine then one day as I was changing the oil, I noticed that the bottom bolt on the alternator was loose. I made arrangements with the mechanic to take the car back and have the bolt tightened. On the day I was to take the car to him the alternator died again, or at least that is what I thought was wrong. The battery/alternator light started to come on while idling just days before, but would go off when I started driving.

I decided to replace the Alternator myself rather than take it back to the mechanic who changed it before for obvious reasons. After replacing the alternator, the battery won't charge at all and runs 20 mins or so or until the battery is drained and shuts off. I have replaced the battery twice, a new battery, the alternator three times only to be told that the alternator was fine when I took it back to the parts store.

The third and current alternator is an high output 250 Amp Alternator from an aftermarket vendor. [Could the aftermarket alternator be the problem?] At the urging of a trusted mechanic I have also replaced the ECU. Prior to replacing the ECU, there was an O² sensor code, following the ECU replacement now I get a mass air flow sensor, air temperature code, and a fuel temperature sensor code, none of which has anything to do with the charging system, battery or Alternator. in addition, the cooling fan does not seem to be working when the engine is running. I have replaced the Alternator fuse, and the fusible link as well. This problem has plauged me for 2 months now and i am unable to drive the car since it only runs on battery power.

Has anyone else had this problem and what did you do to fix the issue? I don't want to but I am seriously thinking of trading the car or just selling it. Any help would be greatly appreciated. I signed up here when the problem first started but am only now deciding to take time to post. Need Help......

XABYTE


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VStar650CL
Posts: 5354
Joined: Thu Nov 12, 2020 1:25 pm
Car: 2013 Nissan Altima 2.5 SL
2004 Nissan Altima 2.5 S

Re: Battery not charging after alternator replacement

Postby VStar650CL » Thu Aug 18, 2022 7:48 am

First thing is to make sure the cabling is good and the charge simply isn't reaching the battery. I know that's a PITA on a G, but it wouldn't be the first time I saw a cable that wasn't fully tightened on the stud or a fusible link that popped during replacement. You should see more or less the same voltage at battery+ as at the alternator stud, usually the drop is no more than 100 millivolts on a healthy cable. If that checks out, get with the aftermarket vendor and make sure the pinout on the 3-pin connector matches the one for the car. You can see the wiring diagram for your system on CHG-15 here:
https://www.nicoclub.com/service-manual ... %2FCHG.pdf

The connector is F36 and the layout is on CHG-17. You're looking at the "Harness Side" of the connector, the side where the wires enter. Pin 2 (Green) is the charge lamp output, it grounds to turn on the lamp. Pin 3 (Violet) is the supply for the field coils and regulator, it must have solid battery voltage at all times. Pin 4 (Pink) is the "smart charging" wire from the IPDM and may be causing a problem. If everything else seems to check out, unpin or clip that wire and see if the alternator output comes up. Disconnecting that puts the alternator on internal regulation and disables the "smart" circuit (which sometimes can get really stupid if something like the battery current sensor malfunctions).

Xabyte
Posts: 2
Joined: Tue May 03, 2022 12:09 pm
Car: 2008 Infiniti G35/37 4Dr Sedan Base

Re: Battery not charging after alternator replacement

Postby Xabyte » Thu Aug 25, 2022 2:39 pm

Thanks for the reply. After further investigation it seems that the IPDM IS/WAS shot. I ordered a replacement. My research shows that you should match as close to your vehicle as possible. This is the donor vehicle INFINITI G37 COUPE G35 G37 SEDAN 2007-2013 OEM FUSE BOX JUNCTION. 73K.
This should be pretty much an exact match shouldn't it?

The problem now is when I attempt to start the vehicle, I get the orange Key light in the dash panel and no accessories and the car doesn't start. The trunk unlocks, the alarm sounds if panic button is pushed, the doors lock/unlock but the engine does not budge. Door chime sounds as well. Battery has a full charge. Should I check the wiring. I was careful not to mix my wires. Could I have crossed something up? Thanks and I look forward to your response...

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VStar650CL
Posts: 5354
Joined: Thu Nov 12, 2020 1:25 pm
Car: 2013 Nissan Altima 2.5 SL
2004 Nissan Altima 2.5 S

Re: Battery not charging after alternator replacement

Postby VStar650CL » Thu Aug 25, 2022 2:57 pm

The IPDM isn't part of the security system, so if you're getting bad lights and no crank, you have the wrong IPDM. Shopping for electronic parts by make-model-year is silly and dangerous. Visit InfinitiPartsDeal.com and enter your VIN, that will pull up the IPDM part number your ride was built with and show any supersessions. Then you can use the Infiniti p/n to google for bargains and be pretty certain you're getting the right part. I'm crossing my fingers for you, I hope you didn't blow anything up.


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