1999 LHS will not start

Hello,
This afternoon I tried to start my LHS, to no avail. The starter cranked
as usual, dash lights came on as usual, everything was as usual except
it didn't start. The gas tank is 3/4 full, and the check engine light
was not lit. I disconnected the negative connection on the pass. fender
panel for about 15 minutes, reconnected it, but still no start. I did
the key on-off trick and the only code showing is P-1684, which is
battery disconnect. When I drove it recently, there were no problems,
and the engine was smooth.
Anyone have any ideas on fixing this or could point me in the right
direction?
TIA
Scott

 

Check for spark and fuel, one of the two will be absent

The most likely culprit for a sudden no-start on these modern engines is
either a dead electric fuel pump (whether due to a relay or the pump
itself), failed auto-shutdown relay, or a bad cam/crank sensor. You'd
need a scan-tool to check to see if the computer is getting cam/crank
sensor pulses, but you can rule out the ASD relay and fuel pump relay by
temporarily swapping in a known-good relay (I usually use the high-beam
headlamp relay). You should also hear the fuel pump whirr for about a
second or two when you first turn the key on, and if its working a fuel
pressure gauge attached to the fuel rail will tell you so (they're cheap
at any auto parts store, and attach with a schrader-valve fitting- easy
for the DIYer).

Good luck!

 

We had that on a 99 300M. Had it towed to the dealer where it started.
That was about 5 or 6 years ago and it never happened again.

My theory was that the factory anti theft system was temporarily confused by
my Toyota Avalon key. I don't think the Chrysler manual mentions it but the
Toyota manual does. If you have 2 chipped keys and the wrong one gets too
close to the ignition switch the car may not start because it thinks the
wrong key is being used.