1996 LeSabre Engine will not crank over

big DIESEL engine.
ONLY 6 CAUSES. FOR NO CRANK
BATTERY LUGS CLEAN? AND TIGHT>
FIRST JUMPER CABLE JUMP START WORK>????
YOU PROVED STARTER IS GOOD.
THE SOLENIOID IS GOOD AS THAT IS WHERE THE JUMP WAS DONE, SOLENOID TINY TERM TO BIG LUG, THERE, PROVES
STARTER AND SOLENOLID ARE GOOD. EASY AS PIE ,KEY OFF SAFE AND SURE WILL NOT START THE ENGINE KEY OFF SAFE

The key most be good and send ST signal (12v) to
PRNDL switch, a/t auto trans right?> not told
then try Park and Neutral to crank, ooops neutral does work>?
the starter relay bad
and list to starter (we know it is good.
all it takes are 2 persons. (one at key other with....)
1 volt meter in hand DMM set to DC volts.
and find the serial point of failures to starter. easy


here is the magic wiring from SM
the fuse 11 ,20amp is first, a 20 cent part. and near zero labor
the EX-F53 MODEL HAS NO FUSE WOW ! A FIRE STARTER.






https://imgur.com/a/7de0WFi


SEE BETTER VIEW

Eliminate the battery as the issue first up.
Check if you can jump start the car from another vehicle with its engine running or at least have the starter motor kick over the engine. If it starts then you know your battery is the issue. Having lights does not mean the battery has enough cold cranking amps to turn over the starter motor.

2. If the starter cranks the engine over as normal with a jump start from another car but your engine does not start you have also eliminated the starter motor as the issue.

3. If it does not start and the starter motor will not crank the engine over either when you jump start from another vehicle, then there may well be a problem with the starter solenoid, the starter motor itself or with the wiring to the starter solenoid or to the starter motor. No power getting to the starter motor solenoid or to the starter motor and obviously the starter motor will not turn over.

4. So I need not write much more here, there is a very good guide to solving starting issues here which I suggest you might like to read.

No Start Problems

you get email when someone answsers. do not double post , please. but do back and see your old post and add more information to the same post , not a new one. (this forum is the worst for structure)
the best would be a real buick forum. trust me.
great the starter is good and battery charged.
so the key line is bad, i posted to your other post with a schematic
and the full testing of that key system.
did you discover this car has PASSKEY system yet? and is the PASSKEY lamp HAPPY? that be first.
back up one post. click the BILL link above. and bingo.

no crank
1: battery dead, not charged. does it jump crank?
2: bad battery (corroded clean em) cables lugs. (4 ends)
3: bad starter /solenoid, assembly
4: engine seized, (turn it by hand you cant?)
5: bad key line, (from key switch to PRNDL to stater , no connections)

jump start it, if passed test, battery bad/discharged , and if fail?
you then (battery is good)
hot wire the starter solenoid, keys in pockets
fail? yes, bad starter, seized engine. turn by hand , now you know.
if passes hot wire test, bad key line. (tiny wire)

easy huh?

The starter is next to the side of the lower engine block where the engine and trans meet(I believe on the passenger side on GM V8s)You should get 12 volts on the small(purple?) wire of the solenoid when the key is turned to "start".If you don't get 12 volts when the key is turned,it could be the switch on the shifter(usually referred to as the PRNDL switch)IF you get 12 volts at the solenoid when you turn the key,replace the starter(my Chevy work truck has gone through 6 starters(ONE A YEAR)since I've had it!)

the security ignition key reader is at fault. A chip is embedded under the keys plastic head. If the module can not read the key no longer the engine will die out after starting.

solenoid clicking, troubleshooting steps: Run 3 tests to troubleshoot.

1. try to jump start at battery terminals
2. unhook the jumpers and try to jump the solenoid following procedures at http://www.fixya.com/cars/r6222268-engine_doesnt_crank_turn_over (see picture there--make sure car is in park or neutral)
3. Only if #1 and #2 fail to crank the engine, smack the starter motor (not the solenoid) with a hammer and then try to start.

Based on results of above tests, here are solution options:

If smacking the starter is the only test that worked, you have a dead spot on the starter commutator--replace the starter.

If it will jump start but will not crank by jumping the solenoid, check to make sure the battery terminals are clean and tight.

If it will not jump start and will not crank even by jumping the solenoid, the problem is either the cable to the starter or the starter/solenoid itself.
check the big red wire that goes from the battery to the starter and make sure it is strong and tight at both ends. If that is good, replace the starter/solenoid.

If it will not jump start but will crank when the solenoid is jumped, the problem is with the start circuit not getting sufficient current to the solenoid. This usually only happens when there is a separate starter relay (in the engine compartment relay box) that is worn out. Replace the starter relay.

Please let me know if you have questions.

Its the starter relay and looks like this

a starter that is bad is bad and no way to jump it this way
the solenoid pushes the drive gear out to the flywheel to crank the engine you see

try jump starting it