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 #193872  by 2fazed
 May 22nd, 2009, 9:06 pm
I bought my 99 Chrysler 300m last September. It had the engine light on, with the code P1684. I knew it's the battery unhooked code. But it's now almost June and it hasn't gone away. Is there anything I can reset or do to get this code gone, without paying the dealership to diagnose it?

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 #193884  by grayslater
 May 22nd, 2009, 10:22 pm
This is not a problem. If there are no DTC's present, the cluster will display one of two texts: "P1684" and "done" or only "done". P1684 is only a status and indicates that the PCM memory has been cleared within the last 50 ignition cycles and does not indicate a problem.

You could try pulling fuses "Q" & "N" for at least 15 minutes to clear codes but you could still possibly come up with the p1684 in theory (PCM memory clearing).

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 #193906  by Bill Putney
 May 23rd, 2009, 6:53 am
I have a theory about that code since it is so prevalent on cars that appear to be operating normally. Starting the car is the biggest load on the battery that it sees, and at that time, there is no alternator output to support the battery either. My theory is that they simply have the voltage threshhold for tripping that code set slightly too high. As the battery ages and the cable connections aren't quite 100%, the dip in voltage that the battery monitoring circuit in the PCM sees at start up is going to be just that much lower than when everything is new and shiny.

Having said that, I would look at the code as a possible advance warning for battery aging, cable damage (serious corrosion), or loose connection issues developing. The only time I got that code on a consistent basis on one of my Concordes, I would reset it, and 9 times out of 10 when I started the car the next day (and it would start fine), that code would appear (and the time on the radio display would reset). I checked thru everything on the power cabling and sure enough, there was some heavy corrosion on the positive battery terminal. Spent a couple hours totally cleaning up and reconditioning that area, and the code/clock reset hasn't occurred since - that was probably 2 years ago.

 #193957  by 2fazed
 May 23rd, 2009, 11:13 pm
I'm going to swap an Optima battery in, with some new battery clamps. See if that works. Normally I wouldn't care about the code, since it doesn't affect the car's performance. But with the engine light on, I can't smog the car. That's why I eventually need it gone.

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 #193958  by EasyRider300M
 May 23rd, 2009, 11:41 pm
Do you know if it's the original battery that came with the car in 99? If it's a newer battery, why not get it load tested first. Autozone i believe does it for free. Also check your cables for corrosion---remove and clean the connections. check the jump posts for good connection too.

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 #193992  by mnitetrain
 May 24th, 2009, 12:04 pm
I agree (again) will Bill, seems like the car's systems detect "some" sort of voltage drop to keep registering that 1684 code.

Being a 99 my guess is the battery cables are probably getting pretty slim by the clamps.

 #193994  by Shadowvox6
 May 24th, 2009, 1:17 pm
It will clear itself in 50 start cycles.

 #194099  by 2fazed
 May 25th, 2009, 8:31 pm
shadowvox6 wrote:It will clear itself in 50 start cycles.



That's the problem. It hasn't cleared in over 200 starts. I have an optima battery from my old car. I just bought new negative/positive battery post cables.

It does make sense about maybe having bad cables or battery. I don't know the history of the battery. It looks like an old interstate. You never know, I did buy it from the original owner. And he took it to the Dealership for all the car repair.

Probably tomorrow I'll swap everything, then after a month, see if it goes away. Thanks.

 #194101  by cloud 9
 May 25th, 2009, 8:47 pm
That code is always present in my 01... but it doesn't trip the CEL. The battery has been in the car for over 5 years and it always started right up... even in the winter and it being -10F.

 #194126  by tinman
 May 26th, 2009, 6:58 am
If you swap out your battery and clean the cables (be sure to clean the jump posts on the firewall/fender, too) the codes should clear themselves in the 15-20 minutes the battery is out.

 #194697  by 2fazed
 May 30th, 2009, 5:49 pm
Well, got the battery in. Got the new cables and changed the post terminals. The posts on the fender are clean too. The code disappeared for 2 days. Then it came back. Don't know if it needs 50 starts to disappear again or there's something else wrong.

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 #194698  by grayslater
 May 30th, 2009, 5:54 pm
2fazed wrote:Well, got the battery in. Got the new cables and changed the post terminals. The posts on the fender are clean too. The code disappeared for 2 days. Then it came back. Don't know if it needs 50 starts to disappear again or there's something else wrong.
Just to clarify....are you saying that the code is still present or are you getting the code and a CEL?

 #194773  by 2fazed
 May 31st, 2009, 10:44 pm
grayslater wrote:
2fazed wrote:Well, got the battery in. Got the new cables and changed the post terminals. The posts on the fender are clean too. The code disappeared for 2 days. Then it came back. Don't know if it needs 50 starts to disappear again or there's something else wrong.
Just to clarify....are you saying that the code is still present or are you getting the code and a CEL?


code and cel