Short story- from my first post as new member here. 133K miles, fleet maintained for 85K miles,then
bought and kept to same schedule myself.

Leaking OEM plastic coolant tubes replaced,and all good. had to take off alternator to do it,
put it back in. Then 20 mile trip. 1 hour first stop then Difficult starting
and rough running for a 2 mile short trip to church. 2 hour stop there. Came out-- no crank, nothing,
got a jump (from a Chevy Volt! yikes)-- it cranked, ran roughly then slowed down and then stopped comletely
Running off the lousy battery,and also-- apparently alternator was not able to over come that .

Towed home. At curbside put in 950 A battery, cranked up and could drive it up to my shop, where it has been.
Alternator OEM Delphi, took it off and tested at two (Advance Auto and O'Reillys) both said putting out 105 Amps spec.
Took OEM starter off tested at same stores---result bad starter/solenoid. Replaced with AC Delco brand new.
New 850 amp battery,and Put the alternator back in. Non digital multimeter tested ohms on alternator cable from B post
to Positive post on underhood fuse box--- got zero ohms (battery neg disconnected).

It cranked and ran the short distance up the drive. Did this testing and replacements. Dash lights up, on "On" Air pump leveler
comes on. Turn to start--- lights go out, release back to On they come back up. Security lockout? So today went through a Passkey III relearn
per Pro Tech GM page here: https://my.cardone.com/techdocs/PT%2077-0011.pdf
Result: same thing-- still no cranking.
Tested all fuses and relays front and back-- all ignition fuses,relays all Start fuses, relays, with battery and ohm readings on the 87 and 30 posts of relays. All good.
Question: The alternator gets a small signal (or should) to activate--when Start is engaged. If the charging cable from alternator has a fusible link
in it and is blown---would this shut off power to the starter? And shut off all the dash lights, and fuel pump signals as well to and from the PCM?

Sorry for the novel. Dad was Navy EE up to first nuke subs-- he loved cars and taught me a lot-- but not this kind of stuff. Thanks, from a famboy.

.

OK- for those interested.
1.) The underhood fusebox had never been opened inside. External cover with red plastic hinged cover for positive post,
comes off . Inside the OEM interior plastic cover needs to come off and maybe can just be pulled of. It had never been
off. Three bolts hold this cover down inside--- loosen them to pull the thing off-- it says "Discard after removal"...

2.) THE BOLTS HAVE TO BE RE-TIGHTENED, to make sure all circuits/plugs underneath are fully linked. IF NOT:
When you engage the "START" on the KEY... Ignition does NOT occur. Dash Lights go out-- and NO CRANK.

3) After checking everything--- everything, as described previous. Noticed these bolts loose tightened them, and
when key is "ON" could hear the fuel pump come on, then turn to START it cranked and started.

This is (and I will search the entire website here) not mentioned anywhere-- probably because people don't
loosen those three bolts. So--- There it is!

Problem solved. Want to thank those who gave suggestions. Certainly know more about our Bonneville and
it is running smoothly and a pleasure to drive highway and city.

Thanks all!

Glad it's resolved. Thanks for circling back.

_________________

95 SLE... a keeper. 241k miles. Low and Slow.
97 BMW 528i
98 Infiniti vq35'd i30: 13.3@104mph, 30MPG Hwy (RIP)
02 Jag X-type
03 BMW M5
05 Chevy Cobalt LS
07 Infiniti G35s 6MT (Sold)
07 Ducati Monster S2R 800 with DS1000 swap
83 Yamaha IT175K
72 Yamaha DS7: '74 RD250 swap, JL chambers

Info on dropping a 92-99: Here.