Crank no start, codes P1685 and P1684

K.M.S

MEMBER
2000 CHRYSLER LHS
3.5L
V6
2WD
AUTOMATIC
249,000 MILES

I spent two days working on replacing the EGR tube, fuel injectors, ignition coils and cleaning the upper air intake and throttle body. The battery was disconnected during this time. Put it all back together, took it for a test drive, no problems, no codes. Rechecked everything, still looked good so I run an errand. It took about forty five minutes, everything was still good. Three hours later when I tried to leave, it started up, I put it in gear, backed up fifteen feet and it cutoff. I tried restarting, but it just cranks and will not turn over, the check engine light is not on. Checked for codes and got p1685 and p1684. Now I am stuck, I have no had the car that long, and I only have had one working key. Any ideas or suggestions?

Thursday, June 21st, 2018 AT 12:06 PM

1 Reply

JACOBANDNICKOLAS

MECHANIC
110,125 POSTS

Hi and thanks for using 2CarPros. Com.

The P01684 does not indicate a problem, but rather that the PCM memory has been cleared within the last fifty starts. This is the result of the battery being disconnected for an extended period.

The P01685 is another story. Most likely, the smart key immobilizer needs reprogrammed.

I am going to provide several flow chart images which are for problem solving this code. You will see the acronym DRB, which is Chrysler's name for their scanner. If you have a good scanner, it should work.

Here is the definition of the issue from Alldata:

SYMPTOM
P1685 - INVALID SKIM KEY

WHEN MONITORED
At ignition key ON.

SET CONDITION
This condition exists when the transponder ID (KEY) read by the SKIM does not match any of the transponder ID's stored in the SKIM's memory. The following could be new or does not match, PCM, SKIM, or KEY.

POSSIBLE CAUSES
Incorrect VIN in PCM
invalid SKIM key not present
NO VIN programmed in the PCM
PCM defective
SKIM trouble codes set

Go through these and let me know what you find or if you have questions.

Take care,
Joe

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