2012 chrysler 200 2.4 liter charge issue

working on a 2012 200 4 cylinder customer complaint he said the battery light was on. brings it to me and no battery light no dtc's except for some in the abs module for high battery voltage. I check the battery wire from the battery it has power. checked the generator field control wire its pulsing it on and off. voltage dropped the negative side got 32 mv. reading live data in the pcm sensed voltage is 14.43. but when measuring it with a meter at the alternator im getting 11 volts. didn't find much information on what this is supposed to read.

11V at the B+ post on the alternator? I'm surprised that the PCM hasn't set a code, with the alternator not charging like that

I usually find that PCM sensed voltage PID to be pretty accurate, not sure how it's reading higher than system voltage. This thing has a OAD dampening pulley on it, right? Wonder if it's freewheeling, not spinning the rotor.

Battery post at the alternator is reading 14 volts. gen sense wire at the alternator reading 11 volts or so. I read that its supposed to read within 2 volts of system voltage. then someone else says its supposed to match system voltage. oh well ill get it figured out tomorrow though

So, I was kinda confused with the 'sense wire' you were talking about... I always found that these two wire Chrysler alternators just controlled the field strength, and didn't 'sense' anything! But, sure enough, the diagram says there's a sense wire:



My bad! :blush:

Have you gone on iATN for this yet? I found a post by Louie Bernstein that is worth reading, if you haven't already:

members.iatn.net/forums/read/msg.aspx?f=...m=379757&fv=3&page=1

What is the modified "A"? One field will be INTERNALLY connected to B-Plus, and the voltage is controlled by PWM to ground of the other field lead. So, then on the modified "A", how are the 2 pins configured? One pin connects to the field lead, so if you ground it the unit will full field. The other lead, on what I dealt with today, is "voltage sense", and it internally connects to the rectifier, or B-Plus, but through a high value resistance, and then to the PCM. What does this mean? When it is charging normally, or if you force it to charge by full fielding it, the voltage on that "sense" line will be LESS than the alternator output voltage. This is normal, and it is how the system is designed.

On the newer Chrysler "B" systems (field internally grounded), it is field energized by feeding a PWM B-Plus to the field pin, and can be tested by doing a direct battery connection to this field pin, as long as you are sure of what you are working on. The sense, again, is not a direct connection to its output, and therefore the voltage on the sense line will be LESS than the alternator output voltage.

This makes it sound like your 11V reading is OK :blink:

ive got a 2013 dodge charger that the exhaust guy is going to be doing some work on tomorrow it has the same set up im sure ill get known good and let you know what is "normal"

Awesome Thanks!

Cheryl this a real puzzle ............ I am very confused by this one :dry:
Many edits in this post
As I understand it (!!!???) purpose of a voltage sensing is allow the regulator control to read the true battery voltage without voltage drop due the high current in the main B+ lead.

The sensed voltage should closely match the voltage measured directly at the battery but this would normally be slightly lower than B+ at the alternator due voltage drop in the main charging lead between the alternator B+ and the battery.

So the PCM should be controlling the Voltage at B+ on the alternator based on the voltage it sees at battery/fuse box/. But that won't explain why it see a heathy 14.x charging voltage when the alternator (edit added) sense is only showing 11 volts Normally if anything the PID voltages read slightly low.
[strike]If the alterntor is only putting out 11 volts the engine should barely turn over.
I assume you have done a sanity check on the DMM ? [/strike]

Edit add to As you can see I am really toatlly confused on this one.
but I do think the sense connector should read very close to battery terminnal voltage

Yeah, it's definitely confusing, Andy. I had a chance to look at the description/operation on this alternator, and this is what I got out of it:

The 'sense' wire is connected to the alternator output across a resistor (dunno the value), which goes to the PCM. In the event that the alternator output cable comes loose, or there's an open in the alternator output circuit, then that sense voltage will read higher than normal, and the PCM will shut the alternator field control off. A safety circuit, more than anything. The resistor explains the low sense voltage.

The service info didn't say this explicitly, but it's my interpretation that the charge rate isn't determined by this sense circuit, but by other inputs. This would explain why the voltage PID never agrees with with sense circuit.

I'm paraphrasing, but that was my take away. I can expand on this tonight.

known good 2012 dodge charger thought it was a 2013 yesterday... measured 14.27 volts at the battery posts. checked the sense wire at the alternator reads 10.8 volts. also didn't think to read what the verus had on in it in the guided component test it says b sense reads 3.5 volts less than the charge voltage so that's what I had with the known good.

Do these cars still use a thermistor on the battery tray? I've seen other Chrysler product's put on the charge light over the temperature sensor circuit being open.

This was a weird one read through, I would have thought that low voltage on the sense line would be a problem myself.

Gotta love that component information in the Verus!

yea noah I shoulda checked to see what was in the verus sooner. but since I had a known good charger sitting in the shop I figured id see what I should be seeing on the sense line. got it wrote down for next time though

It's always nice to have a known good car too

Well I'm definitely smarter now! And I thought I knew Chrysler alternators... :blush:

Did you ever get the battery light to come on, Cheryl? Still wondering about the customers complaint, and how the battery light was coming on with no codes :huh:

that was the first thing I did was check for codes. none. idk why