The Chrysler Minivan Fan Club Forums banner

P1684 code

21K views 11 replies 4 participants last post by  scottydog686 
#1 ·
but no CEL. this displays "SOMETIMES" on the mileage computer.

some said this is battery has been disconnected issue, which it has for getting a new battery but do I have to worry about it?
 
#2 ·
From what I've found, the P1684 Code means that the ECU has lost voltage within the last 50 starts. This could be from disconnecting the battery, a loose or corroded connection, or even a weak battery from repeated or long cranking.
Have you disconected the battery within the last 50 starts? If the answer is yes, then the code will dump itself after 50 start cycles.
Didn't disconnect the battery? Then the ECU has lost power, and you have a problem. Look for bad conections, and bring your walking shoes and a cell phone with you, you'll need them if you cannot find the problem.
 
#3 · (Edited)
P1684 indicates a power interruption and specifically to the transmission control module (TCM) within last 50 starts. It will not normally, by itself, trigger a check engine light. I would suspect an "on its way out" battery or poor battery connections. Since both a stable battery and stable battery connections are the crux of the operation of the electronics of your vehicle, I would take an unexplainable P1684 code seriously.
Take a look here: http://dodge.justanswer.com/questions/g9ns-p1684-code-2003-t-c-3-8-know
Note that all current flows through the battery to the electronics, none is directly from the alternator.
 
#5 ·
That explains the P1684 code showing up. You disconnected the battery. The code will eventually go away after 50 restarts if all is well with the battery power.
As to a "quick learn" on the transmission, disconnecting the battery won't do it. Following a fluid change, by 70 or so restarts the transmission should "relearn" itself. Apparently it has done that. That's some smart transmission. :thumb:
 
#6 ·
Hello

I Have a grand voyager on 2002 year 3.3l which is converted to run LPG as well. I have had it for 1 month and the P1684 code keeps coming up and the engine light is on. Ive had it reset twice and my mechanic says it could be the lamba sensor. Im not convinced so I don't want to change it unless it def is that sensor.

What do you think. Shall I have the battery checked and check the terminals are OK before I get my wallet out ????

Its driving me mad.
 
#7 ·
P1684 should not cause a CEL on its own. There's a glitch somewhere. Are you getting any other codes showing up?
 
#8 ·
Ok No other codes but I ha\ve my battery checked and it's fine but a possible problem with the alternator. Going to have it checked for voltage output tomorrow. I think that is my problem now.

How easy are they to fit. Can I just unbolt the old one and fit a new one or is it belt off and tensioner and a days work !!!!
 
#10 ·
An hours work in a shop. There is a special decoupler pulley on the alternator that needs some special tools. Many Posts on here about that. The serpentine belt needs to be slackened.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top