QuestionQUESTION: I recently had an alternator failure in my 2009 Avenger (about a week ago) and after getting towed off the side of the freeway, replacing the alternator and alternator belt, and giving the battery a charge, everything ran well.
Two days ago, I drove my car to work, and about 2 minutes away, the battery indicator light comes on and I thought, not again! Well I made it to work fine, but when I went to leave at lunchtime, the car wouldn't start. All the electronics worked when I turned the key, but not a sound came from the hood. I thought it was a problem with the starter so I ended up checking some fuses (all were fine), and tightening some connections and to my surprise it fired up just fine.
Anyways, this brings me to my current problem. When I drive to/from work now the past two days (about a 15 minute drive) when I'm about 3 minutes away either direction, that battery indicator comes on. I've luckily had no more issues with starting it, but the battery light is just rather unnerving to keep seeing on my dash. As soon as I park the car and turn it off, if I start the car right afterwards, the battery light is off. The voltage on the battery while running for a few minutes (battery light off) is about 12.4v and when the batter light is running, it is less than 12 volts
It all seems weird to me, I would have said alternator issue if it hadn't been brand new, but I am lost so I figured I'd see if it's more of an uncommon issue that you may be familiar with. Sorry for the long question, but I certainly appreciate any assistance you can provide!
Thanks,
Mike
ANSWER: Hi Mike,
The powertrain control module is responsible for modulating (oscillating) the field coils of the alternator which produces a resultant operating voltage output of the alternator. Because of the new alternator, we might assume that there is an issue with the field coil control wire between the pcm and the alternator.
But there is on-board recognition of such faults which you can check out using the ignition key: "on-off-on-off-on and leave on" doing that in 5 seconds or less elapsed time. Then watch the odometer window of the speedometer to see the mileage be replaced by a 4-digit number preceded by a P. Let me know what that is and we can then go from there.
A plug-in fault code reader is another way to get the code and a nationwide auto parts store such as Autozone will often do that for free. Or an independent shop might charge around $40 for a readout. But try the key first.
By the way the voltage while operating the engine should be around 14V, while the 12.4 is what the charged battery should show when the engine is off.
Please read the PS (below) and respond to it.
Thanks,
Roland
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QUESTION: Hi Roland,
I am unable to get any codes to come up with the key trick, would that only display codes if the check engine light is on? If so, mine is not on, and only the battery light comes on with this problem. Anyways, I understand it is near impossible to accurately diagnose without more information, but if you cannot provide me any other ideas, the idea you suggested is at least a new one. What would be the fix for that issue, or is there a way to actually narrow it down to that with a few tests and readings I could take?
Thanks for your help so far, I sincerely appreciate it!
Regards,
Mike
ANSWER: The other way to get a fault code is using a plug-in code reader. You could possibly get a free code readout at a nationwide auto parts store, or for $40 at an independent shop. Ask for the 4-digit code number(s). It would be good to change out the bulb on the cluster for the check engine light so that approach is also available.
If the voltage reading doesn't increase when you start the engine then it would appear that the wires to the field coil of the alternator is 'open'. So look over all the wires to the alternator for signs of a break in the insulation or a poor connection. My latest manual is for an '05 Avenger which may not be applicable to your '09 model.
Roland
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QUESTION: After further research online, alternating between on and acc three times and ending on 'on', works for the codes, although mine has no fault codes, it just displays dashes and then ends with -done-. Does this rule out your previous suggestion or is that still possibly the cause of my issue?
Thanks,
Mike
AnswerHi Mike,
That is useful to know...so it is 'acc-on-acc-on-acc' that worked or was it something different than that?
Because you got a 'done', that would seem to indicate that you did do a code readout and there are no fault codes. Absent the code, I would focus on the connections at the alternator, and read the voltage on the meter comparing what it reads in the 'on' position with the engine not running vs. with the engine running. Let me know as that will tell us if the alternator circuit is working or not.
Roland
