Oldsmobile/Buick Repair: intermittent starting problem, obd ii scan tool, starter solenoid

Question
I have a 1995 Buick Lesabre that is getting the better of me.  It starts and runs wonderfully for two or three days; and then will not crank or start for several hours or days.  Can drive and shut it off; try to restart it in 15 minutes and engine will not crank; come back in 10 minutes it might or might not crank and run.  Every time I think I have finally fixed the problem, it returns to above problem within a week or less.  I have been trouble shooting it using a service manual.  An OBD II Scan Tool will not check the trouble codes on this auto.  I have checked all fuses, the battery cables, the starter, parts/neutral position switch, ignition switch, and have changed the starter enable relay and the ignition key with the resistor pellet.  I have had no way to check the PASS-Key II Decoder Module.  Please give me some additional suggestions.  Is there any type of bypass that could be set up?  Thank you for any and all suggestions.  Don

Answer
Hi Don,
The pass key system wil prevent it from starting, but should have no effect on weather it cranks the engine over or not.
The way I understand your description, the engine won't even make a noise, or attempt to crank over.
If that is correct, it could be just a loose connection, like where the wires pass through the firewall.Now...that starter is right there on the front side of the engine isn't it?
If it is acting like I said....not operating the starter....I would have a test light handy, and when it won't crank, see if the ignition switch is sending power to the small terminal on the starter solenoid.

A quick test in that area, is to use a screwdriver, or jumper of some sort, and jump battery power from the large battery stud on the solenoid, to that small ign stud. That bypasses all of the switches and safety systems, and if there is battery voltage to the starter, and the starter and solenoid are good, it will crank over.
it will crank over even with the ignition switch off, although it should not start.

it will also crank the starter if the car is in gear, so be careful doing that.

Now...if you mean the ignition switch will actually crank the engine over....but it just won't fire and run....well that is different. That could be the pass-key system, or the fuel pump system, or the ignition system.

But by "not crank"...I interpret "crank" as rotating, or cranking the engine over, and not as starting or firing.

Van