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Last night my Jeep Liberty decided not to run.

It will start fine but only runs for a second and then stalls out.

It's giving the code P1686, which has something to do with the microchip in the key, the thing is that there is no microchip in the key, never has been.

I've reset the computer several times, but still having the same issue.

Any ideas?  

I'm having the same issue with my 2003 Liberty.  Started with no start, jumped battery and all was fine.  Had battery, starter, and alternator checked-all ok.  Today, it will start, but die as soon as you take your foot off the gas pedal.  No codes found.  

Did you find out your issue?  

Hope you are still around and have figured out the problem. Same here, but code P0601 which says it is the CPM  (Computer Powertrain Module).  How did you "Reset the Computer."?  

sorry to the other guys... i cannot catch every post...

P0601...

http://www.obd-codes.com/p0601


text from the above link....


P0601 OBD-II Trouble Code

Technical Description

Internal Control Module Memory Check Sum Error

What does that mean?

Basically that means that there is an interal fault in the Powertrain Control Module (PCM). There have been many reported PCM failures on Chrysler/Dodge products although it is possible for this to happen on any vehicle. In Dodge/Chrysler products, a P0601 trouble code means that a serial communication failed inside the computer at least 6 times.


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Symptoms

Likely, no symptoms will be discernible to the driver, other than the illuminated Check Engine Light. Typically the engine runs fine, gauges work, etc.

Causes

A code P0601 in most cases means the PCM has gone bad. This is possibly due to a short-circuit inside the PCM. Or, if you disconnect the wires/connector from the PCM while the battery is still connected, that may also cause this code.

Possible Solutions

With a P0601 OBD-II trouble code, the most common fix is to replace and reprogram the PCM. In a few cases the dealer may be able to reflash the PCM and get it working. But more than likely the PCM will need to be replaced and reprogrammed (we recommend you take it to a dealership for this). The good news is it *may* be covered under your emmissions warranty. So even if you're out of bumper-to-bumper warranty or powertrain warranty, check your warranty guide or dealer to see if this is covered.

Other people have reported that they cleared the code only for it to return again and again. Keep in mind that most shops can replace the PCM but not all can program it.




more from wayne...

this is going to take a scan tool...

this is going to take access to a factory service manual...

eautorepair.net     or alldatadiy.com    both have the full factory manual...  

but start with having the ECM reflashed..  

there are several Controller area networks running in that jeep..  the ECM and BCM control everything...  like remote control...  each switch sends a request...   the ecm/ bcm sends a digital signal to a digital address via the CAN system running through out that car...

i would really start...  by checking every item...    every light.. every switch.. make sure they all operate...

if you find one that does not operate..  check the wiring to that system.. it could be causing the code P0601


most 1999 and newer cars have over 100 pages of wiring diagrams...  sometimes many more..  there are hundreds of pages of trouble shooting flow charts . for trouble codes...