2012 Dodge Grand Caravan charging system

Hello all.
2012 Dodge Grand Caravan with 85,000 KM on it.

-Charging system error: P0562.

-Driving on highway and battery light came on dash. 200Km later multiple lights on dash: traction control, ABS, airbag. Transmission stuck in maybe third and limped to service station and towed home.

-Voltmeter shows no power to battery from alternator. Initially 12v and quickly drained down to 9V after a few starts and then quit.

-Charged battery and put in an alternator from wrecker with 100,000KM on it. Cleaned electrical contacts. No visible damage to wiring. The alternator I pulled from my vehicle was covered in engine oil as were the conectors from my sloppy oil changes I suppose.

-Now the code persists. At idle the alternator puts out around 14V to the battery. When I bring the RPMs up to over 2000 to run the alternator test with the OBD II scanner the voltage goes up to 16-18v. The battery light comes on the dash, other lights start coming up and the HVAC system stops running at that point. When it goes back down to idle again the voltage to battery is 14V and the HVAC (AC and blower on high) will automatically resume functioning.

-Prior to this charging system failure I was having HVAC problems for about 1,200KM. At idle I would have full power cabin blower but at highway speed the cabin blower would put out very low volume of air. I had not addressed or scanned the issue until I had the failed charging system problem.

-To recap: original alternator would not put out a charge. I replaced the alternator with a used alternator and now it puts out appropriate voltage at idle but with 2000 RPM and more it overcharges just over 18v.

-I haven't replaced the battery but, it tests fine.

-Does anyone have any suggestions as to what to look into next? Can the issue be related to the AC compressor which sits just below alternator?

Thank you.
Matt

Hey Mailloux! I believe you're Caravan uses what I know of as a Kelvin Sense charging system. The short version is of the three wires at the alternator, one is the main B+ cable, one is a power side switched control for the field circuit, and one is the sense wire. Remy has some excellent info on this system - copy and paste this link:

I tried to find a charging system diagram for your 2012, but could only find a 2011. They should be very similar, but check wire colors to be sure:



Just to be clear, when you're seeing 16-18V, is that on the scanner, at the alternator, or at the battery? If you're seeing that voltage at the battery and on the scanner, then I think my first move would be to disconnect the alternator field connection and recheck. If it's still high, voltage drop the alternator case to B- before replacing it again, preferably with new or reman.

Thank you for your help.

The 18V is measured at the battery terminals.

I will look into this and post.

Matt

Gotcha, thanks for the clarification. Let us know what you find with the unplug test, and we can go further.

If the alternator stops charging completely after unplugging it, then we can dig into the field control and the sense circuit.

The car is fixed. I left the alternator from the wrecker in the van and hooked up a new battery. The code still flashed and there was a charge of 18V at the battery. I shut it down and left the car overnight with the battery installed. The next day I started the car and all symptoms had disappeared, a steady 14v charge at the battery and the code was cleared.
Thanks again.
Matt