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Discussion Starter · #1 ·
This past Friday, I noticed coming home that my battery light came on after a short time driving home from where I had just left. I had one more stop, so I stopped, and when I started the car up again, the light was off, but again, came on a short time later. (I haven't noticed for sure, but maybe came on when the car shifted gears.) I drove it home and stayed there for the rest of the day Friday and all of Saturday.

Sunday I took it out and the same thing. Wasn't on right away when I left, but after a time, the battery light came on again. I drove up to AutoZone and had them check, and it came back "Bad Battery." Okay fine. Fixable.

Had AAA out today to change the battery (I just don't have the tools or know-how to change the battery on this car, and my favored mechanic seems to have closed up shop), took it for a little drive after he'd left.

Again, just like before, it wasn't right away, but the battery light came in as I was driving. Drove back to AutoZone, got them to check the alternator, it tested good. Drove back home, and same thing again, light didn't come on right away but it eventually did.

Key dance just throws P1684.

Any suggestions would be appreciated. Fuses,maybe? I shudder to think of it being the PCM but if I have to change that I guess I will.
 

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Need to have someone check what the charging voltage at the battery is with the engine running.

If the cable from the alternator to the battery has issues then that's a possible issue along with corrosion at the battery post clamps. And the PCM Powertrain Control Module controls the charge rate aka alternator output.

PCM issue is rare. I'd have someone concentrate on the cabling from the alternator to the battery.
 

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Discussion Starter · #3 ·
Thanks @Ronbo. Lifting off the airbox and checking for corrosion I can do, and will do. I'll go back to AutoZone tomorrow and ask about the charging voltage with the engine running, I'm assuming that's something they can check for me. I'll see if I can enlist my way-better-at-cars-than-me racecar driver brother in law to check that cabling.
 

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There is a Fusible Link inside the cable going from the Alternator to the Positive Battery Post. It's been known to have corrosion under the insulation of the cable affecting the link and continuity between the Alternator and battery positive post. The corrosion won't be visible inside the cable and a continuity check would be the only way to detect it. Or replace the cable.

Text Diagram Floor plan Technical drawing Plan
 

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Discussion Starter · #5 ·
For some reason that attachment is coming up not found.

EDIT: Guess I'm gonna have to find a shop to check the continuity.
 

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Reload it
 

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Discussion Starter · #7 ·
Got it. I'll see if I can find someone who can check continuity tomorrow. It's getting dark and things are closing up for the night.

I'll keep you updated.
 

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(I just edited this post due to some errors in what I said. Info. should he correct now.)

One comment: The auto parts store may have checked that the alternator is charging by clipping to the output stud on the back of the alternator. If the fusible link is severely burnt or corroded and they measure voltage at the back of the alternator, the alternator will test fine - but the battery connection to the alternator (thru the fusible link) is so weak that the battery is not getting charged (too much resistance in the fusible link).

As Ron said, if the positive jump post has high resistance due to loose connections or corrosion, and the fusible link is in decent shape, you could have the symptoms you described, but that will also cause excessively high voltage out of the alternator, which would severely overcharge your battery (damaging it over time).
 

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Discussion Starter · #9 ·
I think I'm gonna just bite the bullet and get the cables changed. It's just going to have to wait until next week because I'm living on unemployment right now because waves hands around. I'll check the connections to the battery, which is easy enough to do on my own and I can tighten and clean those up myself. Anything further than that is beyond my skill, and racecar driver brother-in-law is also currently working 50 hour weeks, so I don't want to take his weekends away from him by foisting my old as s**t car at him and being all "PLZ FIX!" My mother has a mechanic she really likes so I'll get an estimate from them, and see if they can check the continuity.
 

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Discussion Starter · #10 ·
This morning, just to try and see if it was a thing when the car shifted gears/accelerated, I went out and started it up and just let it run. About 3-4 minutes after starting it, the battery light came on just like it did when I was driving it. I'm gonna wait for it to cool back down - and for it to warm up outside, it's kinda chilly - and I'll take a peek at the terminal. I dropped an email to my mom's mechanic (a local and locally-owned chain) about coming down and checking the continuity and charging voltage and if they get back to me, I'll head down there.
 

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Discussion Starter · #11 ·
Welp. It's definitely the alternator. The charging voltage is only 11.92v. My shop did change out one of the terminals that had gotten very loose, but the alternator is just on it's way out. So, I'm looking at a very costly repair.

Thanks for all your help @Ronbo and @peva , I wouldn't have thought about the stuff you told me to check. Thanks again.
 

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How "Costly" is the repair going to be? What are they going to charge for an Alternator?

What engine do you have? 3.5/3.2 is easy-peasy...it's right up top. The 2.7 sucks donkey ballz as it has to be accessed from under the car.
 

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Discussion Starter · #13 ·
$177 for the alternator - local junkyard doesn't have one, sadly, and I'm not really wanting to hedge my bets on a refurbed one.
$300 for the install because it's a 2.7.
 

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$177 sounds way too cheap for a new alternator. I'm going to say it's a rebuilt/reman with markup. They're about $115 at auto parts stores.

A remanufactured Denso OEM alternator from Dodge would probably be at least $300.

The labor isn't a surprise. Start saving your pennies!
 

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Hi everyone. I'm a new person here and I just want to say hello. And I have a similar problem. The system is fine, but error P 1684 remains(((
 

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$177 sounds way too cheap for a new alternator. I'm going to say it's a rebuilt/reman with markup. They're about $115 at auto parts stores.

A remanufactured Denso OEM alternator from Dodge would probably be at least $300.

The labor isn't a surprise. Start saving your pennies!
Rock Auto:
AC Delco 'Professional' line new @$110 plus shipping
Remy new @$110 plus shipping
either woukd be an excellent choice

Rock Auto:
Mopar rebuilt $160 plus $60 core plus shipping
 

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Hi everyone. I'm a new person here and I just want to say hello. And I have a similar problem. The system is fine, but error P 1684 remains(((
Hi Daria. Welcome!

I know the subject is similar, but could you start a new thread? Less confusing for everybody.
 

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Discussion Starter · #18 ·
@Ronbo @peva I'm hoping maybe one of you can answer me. I'm sorry to dredge this up again, but... I have got to take my dog to the vet on Monday and the only vehicle I have is... well. My Intrepid with a bad alternator.

It's not terribly far, not even five miles away. I'm not going to ask if it's "safe" to drive it, but... would driving it that little ways and back irreparably harm anything?
 

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If your alternator isn't charging, then it should not damage anything to drive it, though your battery may run down.

I'm not convinced you have the right diagnosis yet, depending on exactly where the placed the voltage measurement probes.
 

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Discussion Starter · #20 ·
Alright, I think I'm going to not risk it and I'll just reschedule the vet appointment for after I get my new alternator. I don't want to be stuck somewhere with my dog waiting for a tow while she loses her tiny little mind. Thanks.
 
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