Troubleshooting Periodic Charging System Fault

[The_Nuke]

(Car in question is a 2010 Dodge Challenger w/ the 3.5L)

A couple of months back I was surprised when the battery light on the dash lit up after starting car one night. It had never done that, so I immediately turned off engine and restarted it. The light was gone, so I went on about my business. Only later did I check for DTCs just in case (CEL never illuminated) and found one - P0622, which basically indicates a fault in the charging system has been detected and the end result is no alternator charge delivered to battery (while battery light lit up on dash) and the DTC set in memory.

Since that initial occurrence, it has happened 4-5 more times, each time a little less time elapses between events than previously (started out 14 days between them, then a week, now last 2 events within 3 days of each other). So things are coming to a head it would appear.

But unfortunately I have been unable to identify what the problem actually is.

Each time the fault occurs, I have been able to resolve it (restart alternator output) by either stopping and restarting the engine or removing and re-tightening battery cables on battery posts. They didn't require cleaning, and all I did was loosen the bolts and pull off posts for inspection, and then replace on posts and tighten down. That worked the last 2 times when restarting engine wouldn't.

I have been able to verify the battery is good, and it's only a year or 18 months old anyway, so wouldn't expect problems from it yet. The alternator is even younger (maybe a year old), so wouldn't expect it to be acting up either. Car itself has 100K miles on it, but I take care of the vehicle and do regular maintenance for all service intervals, and I've never found anything amiss that would lead me to believe things are just falling apart.

So it's down to the point of everything works great, until it doesn't, at which point the alternator is no longer charging the battery and I have to somehow make it charge again. Once I do that, by whatever means, everything is fine again...until next time.

Internet searches have mostly yielded posts and threads related to this DTC on GM vehicles, but even then I have tried to rule out the issues mentioned in those as culprits, just in case. The wiring on the back of the alternator was a big one in most of those threads, but I cannot get mine to act up by any manipulation of those wires. It's as if they are good, and they are connected securely, so I am assuming they are.

Alternator itself? Well, it would have to be tested while "in fault" wouldn't it? That's what I'm guessing, and haven't had the guts to pull it off yet while in fault since it's always happened while out about in town. If it would happen at home, I guess I could pull it and have it tested thoroughly. But from what I've read, the alternator doesn't sound like the likely suspect for this issue, it's usually somewhere else in the charging system, so I'm reticent to start dismantling things just yet (not to mention the alternator's a witch to get off/on and this is our only vehicle at the moment).

Any ideas anyone has on troubleshooting further or personal stories of dealing with this nasty little DTC would be much appreciated, as I'm about at my wits end trying to get past this particular issue!


thanks,
nuke

 

[Donald]

I would start by removing, cleaning, dielectric grease and re-installing all grounds in the engine area as well as battery cables and alternator wires.

If you pull the alternator and bring it to a place that rebuilds them he should be able to give it a good test. AutoZone does not have the knowledge.

 

[Linctex]

Next time it happens, leave the car running and slowly pour cold water on the alternator & see if it charges again.

I was in Fort Worth last July & the same thing happened to me. I managed to make it over 100 miles home by giving it a cold bath every 20 mins. I never took it apart to find out what was wrong internally.

 

[Linctex]

Having said that... Chrysler products have WEIRD electrical systems.

If it isn't the alternator itself..... good luck!

 

[69GTX]

I'd verify voltage drops are
I'd also test the firewall ground straps too. There are more tests you could do by Googling this topic.

 

[yvon_la]

Wire weren't properly spaced apart and from steel and it resulted in various electrical problem . So alternator is 1 year old? So it means the other one was 5 years old .ya its about where grimlin start to appear that you would notice. Now? You ll need to go to dealer and fix what blew . Could be anything . If you have a garage do a bumper to bumper wire check .you ll know when you see it .yes you could add space to wire but it's not gone fix the problem (maybe its just at the beginning and hasn't blown anything yet.

 

[zzyzzx]

I would be checking the alternator brushes. They may be worn o the point of causing intermittent charging. Having said that, I would normally expect alternator brushes to last to around 150K miles, and you only have 100K miles, and since it's a Chrysler, look for bad grounds and wiring.

 

[andyd]

Aw geez, that sounds like a loose connection. No parts required. Total pain to find. What was the last under the hood service ? On my 528e, the idiot light being loose in its socket would be enough to cause this symptom. 69 GTX is giving logical clearcut procedure. A loose ground between engine and fire wall. raises all kinds of weird things. I would start with the battery and the alternator connections, mainly because the they have been replaced and then the issue began. Alternator quality doesn't impress me of late either.

 

[Oro_O]

69GTX's post will get you the answer. My suspect is the alternator rectifier diodes as this is how they can present when failing. I would expect AC ripple voltage to be found.

Some auto part stores also have alternator test devices that can be perrformed on the car. Replacement rebuilt alternators (where did yours come from?) have a very high failure rate. I replaced an 18 month old one recently.

 

[The_Nuke]

Originally Posted By: Or
69GTX's post will get you the answer. My suspect is the alternator rectifier diodes as this is how they can present when failing. I would expect AC ripple voltage to be found.

Some auto part stores also have alternator test devices that can be perrformed on the car. Replacement rebuilt alternators (where did yours come from?) have a very high failure rate. I replaced an 18 month old one recently.


Alternator is one of the remanned ones from a local O'Reilly Auto Parts.

I foresee eventually taking it back to them to have it tested, but my fear is that if it is a bad alternator (due to internal part such as you referenced), their testing equipment wouldn't necessarily indicate such unless the alternator was actively in fault when I removed it, leaving me with the same situation I had when I started but also being out the effort and time of removing it from the car.

*SIGH*

Either way, it's not going to fix itself, so I need to either make a stool or get off the pot I reckon...

Thanks for all the replies everyone, I really do appreciate the feedback and help!!

Nuke

 

[Yah-Tah-Hey]

Originally Posted By: zzyzzx
I would be checking the alternator brushes. They may be worn o the point of causing intermittent charging. Having said that, I would normally expect alternator brushes to last to around 150K miles, and you only have 100K miles, and since it's a Chrysler, look for bad grounds and wiring.
Right on XYZ. That is what came to mind.

 

[Eddie]

As mentioned by Donald, I would go after the grounds before anything else. Ed

 

[Oro_O]

Quote:
Alternator is one of the remanned ones from a local O'Reilly Auto Parts.

I foresee eventually taking it back to them to have it tested, but my fear is that if it is a bad alternator (due to internal part such as you referenced), their testing equipment wouldn't necessarily indicate such unless the alternator was actively in fault when I removed it,


That was were I got the one that failed on one of our cars after 18 months.

The tester should show the fault regardless of the CEL, as its likely a rectifier diode based on the symptoms. If it is a bad rectifier, do not drive the car excessively or you risk further electrical system damage (including possibly your PCU), and they aren't going to warranty that. Take it by there tomorrow.

Unfortunately, In my case it was a situation on that vehicle of "need it today." If you can take the vehicle out of service for alternator repair, taking it to a local shop or doing it yourself is a much better bet these days. My SUV needed an alternator last year, and I rebuilt it myself since I could live without it a short while.

 

[The_Eric]

Here is what the factory diagnostics says for potential causes of this code
Code:
(K20) GEN FIELD CONTROL CIRCUIT SHORTED TO VOLTAGE

(K20) GEN FIELD CONTROL CIRCUIT SHORTED TO GROUND

(K20) GEN FIELD CONTROL CIRCUIT OPEN OR HIGH RESISTANCE

(A804) GEN SENSE CIRCUIT OPEN OR HIGH RESISTANCE

GENERATOR

POWERTRAIN CONTROL MODULE (PCM)



If you want, send me your e-mail and later on, I can scan and send you the schematic and diagnostic info on this. It will have everything, including harness plug views.

 

[The_Nuke]

Originally Posted By: The_Eric
Here is what the factory diagnostics says for potential causes of this code
Code:
(K20) GEN FIELD CONTROL CIRCUIT SHORTED TO VOLTAGE

(K20) GEN FIELD CONTROL CIRCUIT SHORTED TO GROUND

(K20) GEN FIELD CONTROL CIRCUIT OPEN OR HIGH RESISTANCE

(A804) GEN SENSE CIRCUIT OPEN OR HIGH RESISTANCE

GENERATOR

POWERTRAIN CONTROL MODULE (PCM)



If you want, send me your e-mail and later on, I can scan and send you the schematic and diagnostic info on this. It will have everything, including harness plug views.


Sure, having that information would be great. I may have to give my electrical troubleshooting skills a serious refreshing to be able to use it, but I will always opt to have more useful info than I can use over the opposite.

Many thanks!

 

[The_Nuke]

Originally Posted By: Or
Quote:
Alternator is one of the remanned ones from a local O'Reilly Auto Parts.

I foresee eventually taking it back to them to have it tested, but my fear is that if it is a bad alternator (due to internal part such as you referenced), their testing equipment wouldn't necessarily indicate such unless the alternator was actively in fault when I removed it,


That was were I got the one that failed on one of our cars after 18 months.

The tester should show the fault regardless of the CEL, as its likely a rectifier diode based on the symptoms. If it is a bad rectifier, do not drive the car excessively or you risk further electrical system damage (including possibly your PCU), and they aren't going to warranty that. Take it by there tomorrow.

Unfortunately, In my case it was a situation on that vehicle of "need it today." If you can take the vehicle out of service for alternator repair, taking it to a local shop or doing it yourself is a much better bet these days. My SUV needed an alternator last year, and I rebuilt it myself since I could live without it a short while.



Well, there goes my weekend

That's a shame too, because I had planned on finishing up my proposal for a ground-breaking peace initiative for the Middle East.
Oh well, gotta get my baby back to a healthy state first!

thanks for the info,
nuke

 

[Oro_O]

Dude, you live in Dallas and it's going to be 90F tomorrow! Better to be indoors in an airconditioned garage than outdoors getting heat stroke! (Having lived in/around Seattle the last 15 years, I can no longer take heat -ugh).

And besides, why shooy yourself in the foot with a new Mid-East peace plan? What's bad for them is good for West Texas Intermediate! I've got a friend in Arlington in the oil rights leasing business, I'l have him come around and distract you on that project for a good long time...

 

[The_Nuke]

Originally Posted By: Or
Dude, you live in Dallas and it's going to be 90F tomorrow! Better to be indoors in an airconditioned garage than outdoors getting heat stroke! (Having lived in/around Seattle the last 15 years, I can no longer take heat -ugh).

And besides, why shooy yourself in the foot with a new Mid-East peace plan? What's bad for them is good for West Texas Intermediate! I've got a friend in Arlington in the oil rights leasing business, I'l have him come around and distract you on that project for a good long time...

Air conditioned garage? Does such a nirvana really exist?? I WANT ONE!!!

Yeah, it's hot now, but it's not yet to the point of being brutally, oppressively hot...yet. I give it about another month, and then doing anything in the garage will be limited to an hour or so, and that's with several fans blowing directly on me. Anything beyond that risks dehydration and heat stroke, which is still difficult for me to fathom given that I'm in the shade

 

[The_Nuke]

Just in case someone else out there finds this thread while searching for 'P0622', I figured a quick update might be in order.

I have not pulled the alternator off to take it somewhere to be tested yet, mostly because no place that I have called has given me confidence they can test it adequately off the vehicle. Everybody says "oh you don't need to pull it, we can test it right there on the car." Yeah, I know, but that's not the test I want performed. Whatever, just to be thorough, I went ahead and let one place do that test, and surprise, surprise, it passed.

I got ahold of the testing and diagnosis steps for the P0622 DTC from the service manual, but I have not performed them. Following the steps to the 'T' requires the use of a scan tool to activate the generator field without starting the engine. I do not have a scan tool that can do that, and so I cannot follow the diagnosis steps completely. I know some might say I could just start the car to activate the generator field and test from there, but I am reticent to do that for several reasons:

1. My electronic troubleshooting skills are rusty and not to be completely trusted, and so using them on a running car's charging system is an invitation for trouble IMO.
2. No matter what the outcome might be, I wouldn't completely trust those results since I was not following the steps exactly as laid out.
3. The DTC has to be active before beginning the steps, and mine is currently not in fault.

But rather than sit back and wait for it to happen again, I figured doing all the other little stuff was my best move for now. So I went ahead and did as some have suggested and removed and cleaned all the PCM and engine grounds in the engine bay and the PCM and battery grounds in the trunk. None of them were corroded or otherwise suspect in holding a good ground, but the one for the battery in the trunk was off-kilter with respects to the ground wire lead and nut holding it down. For this one I added a washer between the lead and the nut to ensure a better clamp and hopefully connected surface for grounding the battery.

I have not had anymore P0622 incidents since doing this, and in total it has been over 7 days and almost 1K miles since the last one. Averaging out all the previous faults by time and mileage, I should have experienced 2 more in that time, so I'm cautiously hopeful cleaning up all the grounds did the trick.

I'll update this thread if anything else happens...or doesn't happen.

Thanks again for the help,
Nuke

 

[The_Nuke]

Alright, it's been long enough now without another fault that I feel confident declaring this issue [SOLVED] and marking this thread as such.

I must say I am surprised it wasnt something more difficult and expensive to find and resolve. That's usually more what I encounter when things go wrong mysteriously, but I wont complain, I like cheap and easy too!!

Thanks again for everyone's input and advice!

Nuke, OUT!