ok so last night my service charging system light came on while I was on the way home, I tried to make it home and that was a fail . After about 10 minutes the battery had started to drain and shut off some accessories until it completely died and left me stranded . So of course I do t have warranty so I bought a new alternator and had my optima warranty.. well this morning after installing both parts it only took about 10 minutes of idle before the service charging system popped right back up.. maybe about a month ago I had the starter changed . That’s about it .. everything else on the car has been the same for about 2 years now.. any ideas what could be causing this ..

I did the old school alternator test by pulling out the battery while the car was running to see if the alternator would keep it on and it did.. not sure if that old test applies to these cars but I thought I would give it a shot..

 

You didn't state whether or not you had the battery tested...any time you have an issue with your charging system the battery and battery connections should be the first thing checked before doing anything else. You just need to have the battery charged and then load tested.

 

Check the cable connections at the starter. Known problem point on our cars. I ran a 1/0 copper cable from the Alt to the power take off point on the side of the fuse box and capped the factory cable going to the starter from the Alt. No more problems.

 

 

 

Can you share more details? Why did this fix the issue, in your eyes? Maybe some pics? I've been fighting this issue for a while; only occurs when sitting idle. Tap the gas, goes away.

Thank you,
Jeff

 

Jeff, going to make trouble shooting easy for you.

Motor running, A/C off and a multi-meter in hand set to DC.

Body of the alternator as your ground, terminal on the back of the alternator as your positive source, should get a reading of 14.7 volts.

Next, using the the battery terminals, should get 14.5V. If you get lower than this, then use the positive battery terminal as positive, but use the alternator body as ground. If the voltage when up, then the ground cable to the engine bolt has a problem. If the voltage did not go up, the where the battery to alternator cables connect on the starter solenoid have a problem isntead.



If you voltages are still good (14.7, and 14.5 at the battery), then next pop open the engine fuse box, and test from the fuse box terminal to the negative on the battery, and then to the alternator body as your ground. Should have 14.5 volts either way.

Now get in the car, click the DIC to voltage, and the reading on the DIC should be 14.3 volts.
Huge note here, the DIC and dash analog dial are not reading voltage at the dash, then are giving you the voltage at the ECM. Hence power goes from the engine fuse box, to the BCM, and then down line to the ECM.


Tell me where you are getting the low voltage reading, and I will tell you where you have the problem.

If all the way back at the alternator, I did a write up on how to pull it apart and solve most of the problems there, but also could be the alternator good, but you are using aftermarket spark plugs and wires.

Hence the OEM spark plug and wires have a high resistance to them to prevent RF noise feeding back through the coils to the ECM, since if the ECM is getting RF noise through it, it will clip the output voltage of the alternator.