2014 Mazda5 goes nuts

Looking for some help if anyone has experienced this. I do all my own Cummins work but not much on the GFs Mazda 5. So heres what I have. Two weeks ago. She was driving to get the kids at school, looses power steering turning into parking lot. She parks turns it off, battery is completely dead. I go jump it and it starts and runs. Scan it and it throws U0100 lost communication with engine control module A. I keep it hooked to the jumper cables to charge the battery enough to drive it home. Get it home. Starts and runs fine. No codes or anything. It had been showing battery light off and on for a few weeks. We had replaced the alternator and the battery within the last 90 days. So anyways runs fine. Starts and idles for 45 min. GF drives it for the last two weeks without any issues. Then today Im driving it and lose power steering. Then the steering light comes on, then the abs light followed by the traction control and such. I pull over and figure Ill turn it off and see if it resets. Battery is dead. It will crank but barely. Jump it, fires up and idles. Warning lights stay on, no power steering. No speedometer. Get it home in what seems like limp mode with the transmission jerking a few times and throttle not responding. It revs to 3,000 but doesnt accelerate. I hook the battery to a charger and come back a few hours later and run diagnostics. I get P0500/P0884/P061B. I erase the codes except for 0884 and 061B because it states it cannot. Starts up, no check engine, no other lights and everything works again. I dont see any loose cables, transmission has oil, alternator shows 13.6 at 3,000 rpm. So what am I missing? It did it turning left, the same way when it did it to my GF.

I would check the battery cables. Look them over REALLY GOOD. Twist/bend them a bit and make sure they aren't corroded internally. Cables can totally look fine but be rotten inside. Although I wouldn't expect them to be rotten so soon on a 2014. Was there corrosion on any terminals when you replaced the battery? Whenever I get corrosion on a terminal that comes back after I clean it up, it winds up being a bad connection or cable further into the wiring harness.

Battery light being off and on seems like there is a bad connection somewhere....and faulty power would explain all this.

negusm said:

I would check the battery cables. Look them over REALLY GOOD. Twist/bend them a bit and make sure they aren't corroded internally. Cables can totally look fine but be rotten inside. Although I wouldn't expect them to be rotten so soon on a 2014. Was there corrosion on any terminals when you replaced the battery? Whenever I get corrosion on a terminal that comes back after I clean it up, it winds up being a bad connection or cable further into the wiring harness.

Battery light being off and on seems like there is a bad connection somewhere....and faulty power would explain all this.

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Ill check the cables. When it did it the first time, the negative was slightly loose so I tightened and suspected that may of been the culprit. I do not recall any corrosion on the terminal. It does have dielectric grease on the battery posts. I am also leaning towards a connection somewhere, I just dont have a schematic to track down wiring and where it goes. I thought also maybe the alternator has some type of fault Im unaware of that is causing intermittent issues but again, that would not be something Ive ever run into with alternators.

How old is the battery? If its original, it is at least 5 years old. That is old enough to start having problems. If it's turned up dead a couple of times already, I would change it out. Cheap insurance.

njaremka said:

How old is the battery? If its original, it is at least 5 years old. That is old enough to start having problems. If it's turned up dead a couple of times already, I would change it out. Cheap insurance.

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The battery is new. Bought a few months ago. Optima Red top