2000 Buick LeSabre Intermittent start, strange behavior! PLS HELP!

2000 Buick Lesabre ignition problem... Starter and ignition switch already replaced.
Intermittent starting, idiot lights remaining on occasionally and tachometer not working properly.
The car only starts now occasionally, either nothing when the key is turned, or a faint uhhhhr sound followed by a screech like that of a key being turned in a vehicle already running, then it catches and starts.

Pertinent history- One month ago the car started misfiring suddenly one afternoon, ran REALLY rough. After replacing the plugs, wires, coil packs, fuel filter, belt tensioner, serpentine belt, pcv valve, we tested the ignition control module and it failed. Once this was replaced, the car has been RUNNING perfect, but within TWO DAYS this NEW problem began. Possibly related?

Car also emits a faint burning plastic odor occasionally.

Any clues??

Welcome Aboard!

What happens with the "SECURITY" lamp when the ignition key is turned on (without starting the engine)?

The security light remains on, even sometimes AFTER the vehicle is started. This was the first light that was acting strange.
Thanks for taking the time to respond...

You could have several problems here, so let’s start with some of the basic diagnostics. :sunglasse

Have both battery cables & terminals been sanitized? Has the battery been load tested? Has the alternator been checked for proper output!

Your starting problem sounds like typical symptoms of erroneous voltage! Intermittent voltage spikes, can cause instantaneous & irreversible damage to the PCM! :uhoh:

Try turning on the ignition without starting the engine (it's a good habit anyway, for several reasons).

When you first turn on the ignition: Listen for the fuel pump to run its two-second prime cycle; Watch the "Check Engine" lamp - It should turn on for about 1/4 second, turn off for about 1/4 second, then turn back on and remain on until the engine is started; Watch the ABS warning lamp - It should turn on for a few seconds, then turn off; Watch the SIR or "Air Bag" warning light - It should turn on briefly, then flash 4-6 times depending upon the number of sensors installed, then turn off; Watch the "Security" lamp - It should turn on for 4-6 seconds, then turn off. If the light remains on, either the door is open or the PassLock system has a fault.

If any of those systems do not initialize normally, that's a clue to a possible problem(s).

I wanted to say THANK you to everyone first of all, I finally broke down and took it to a mechanic.
To update, after two days he found the problem, the stud by the front fuse box had been shorted and was melted, so the box was only receiving about 8 volts of power.

IT WORKS AGAIN!! PHEW! haha


Again, thanks for the input! This ended up being just one of those things...

Try turning on the ignition without starting the engine (it's a good habit anyway, for several reasons).

When you first turn on the ignition:
Listen for the fuel pump to run its two-second prime cycle;
Watch the "Check Engine" lamp - It should turn on for about 1/4 second, turn off for about 1/4 second, then turn back on and remain on until the engine is started;
Watch the ABS warning lamp - It should turn on for a few seconds, then turn off;
Watch the SIR or "Air Bag" warning light - It should turn on briefly, then flash 4-6 times depending upon the number of sensors installed, then turn off;
Watch the "Security" lamp - It should turn on for 4-6 seconds, then turn off. If the light remains on, either the door is open or the PassLock system has a fault.
If any of those systems do not initialize normally, that's a clue to a possible problem(s).

Hey, thats some great info! I've never even thought of turning the key to "Run" position to check the warning lamps.:smokin: