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Discussion Starter · #1 ·
Hello,
Since Jan 2022, the battery and brake warning lights (exclamation dash light) have been appearing on my dash when I start my car after it's been sitting idle overnight. Both warning lights disappear after driving at 50km/hr for about 10 minutes.

My mechanic opted to change the car battery as the alternator was showing no signs of problems. The warning lights only occasionally appeared after the new battery was installed in Jan 2022 and eventually the warning lights stopped appearing.

July 2022 the battery and brake warning lights start appearing again on my dashboard. Back to the mechanic. The tests now show that the alternator needs replacing. Ok, I get that done. And it's pricey! I drive my Altima about 10km and the warning lights appear again on my dash! Back to the mechanic. A new alternator is installed. I pick up my car and drive it around town doing errands. All seems good, and with no warning, the car just dies. Very scary! Thankfully, I could pull over to the side of the road. My car was towed to the mechanic where it sat overnight. The mechanic started it up with no issues this morning and both the battery and alternator are showing no problems. Help! What could be the issue? I HATE driving my Altima now as I'm afraid it could suddenly die! Any suggestions??? Thanks.
 

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Check all the power and ground connections for the battery, with particular attention to the main ground cable where it attaches to the transmission. Also inspect the fusible link "card" on the battery for hidden cracks. I've seen several instances where fatigue or abuse caused the busbar inside the card to split, making it intermittently lose contact. All the power to every part of the vehicle runs through that card in some fashion, so a faulty one can produce every sort of electrical mayhem you can imagine.
 

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Discussion Starter · #3 ·
Thanks. I'll have the mechanic look into that. My mechanic is suggesting that a control associated with thr steering column is not allowing the battery to fully charge. My car is now being towed to a Nissan dealership for them to investigate.
 

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Thanks. I'll have the mechanic look into that. My mechanic is suggesting that a control associated with thr steering column is not allowing the battery to fully charge. My car is now being towed to a Nissan dealership for them to investigate.
Follow @VStar650CL's suggestion. Also test the alternator; A properly working charging system puts out about 13.2 to 15.0 volts. When replacing electrical components such as alternators, starters, fuel injectors and sensors, always replace with new or reman'd Nissan OEM components; aftermarket components generally don't last long, don't work right and many times are DOA.
 

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Discussion Starter · #5 ·
Thanks for the advice. My car is now at a Nissan dealership, and apparently there is a significant backorder for an OEM Nissan alternator for my 2009 Altima. So I'm out of luck and need to have an after market alternator installed by the dealership. This will be the THIRD alternator installed in a week.
 

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Discussion Starter · #6 ·
Aug 8 update: So alternators #1 and #2 were installed by my mechanic at a cost of $1000 Cdn. This didn't fix the issue, so the car was towed to Nissan dealership.

Nissan mechanic was certain that faulty and poor quality alternators were used by my mechanic. He was 90% certain that a better quality alternator would solve the problem. After some debate, it was decided to have yet another alternator installed. Another $1000 mechanic bill!
Just received a call from Nissan. They replaced the alternator, only to find out that this is NOT the problem!!! Now they want more money to complete additional diagnostic tests. I was told that perhaps the accelerator is not connecting properly with the battery causing the battery to die. It may also be faulty wiring somewhere in the battery circuit that is not allowing the battery to charge.
Please help. Any suggestions? I am livid about paying Nissan $1000 to replace my alternator that did not even require replacing! My car is apparently charging, but once you start driving it, the power cuts out. Advice?
 

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Gen4 Alties all have a "smart" charging system. Note the Green wire I marked in the diagram below running from the IPDM to the alternator. That's a PWM signal telling the alternator how much current to put out. The BCM actually controls it by passing instructions to the IPDM via the CANbus, based on the Battery Current Sensor located on the main ground cable. Since it's at a dealership, the first thing they should be doing is reading the alternator duty% from the IPDM to see if the BCM is commanding a very low output level. If so, you probably have a bad Current Sensor which is lying to the BCM. The "cheap out" for problems with the smart charging setup is simply to disconnect the Green wire. That puts the alternator in "self regulation mode" and it will output around 14V constantly. That's also a good "quick check" for whether the smart charging is causing the issue.
Rectangle Schematic Font Parallel Slope
 

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Discussion Starter · #8 ·
Thank you for sharing that information and diagram. I appreciate your help and will pass this suggestion on to the mechanic. Thanks!
 
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