Here the further story:

I also have a 94 Bonneville ... so ... today I got into the Bonne trunk and disconnected that 3rd-brake-light bulb-socket (same GM part # 05972532) from the OE wire-harness and from the light-house assembly.

After un-screwing the 1156 bulb from the Bonne 05972532 socket, I ...

For my 1999 LeSabre (but likely same for 90's Bonnevilles):

High-Mount brake light wasn't working ... so replaced the 1156 bulb ... still didn't work.

So: disconnected the bulb socket from the harness connector and looked inside the socket with magnifying glass.

Looked like the socket-tube side ...

Regarding immediate-above post
"... re-engineer with a DIY-switch-relay direct to the coolant fan wiring ...":

Over the past week, my 1st inclination for re-engineer was 2 aspects:
A:
butt-connect the low-speed wire from the up-front fans harness into the harness hi-speed wire path (so hi-speed ...

ok ... found where the coolant temperature sensor is ... not pretty ... in terms of access.

Sample view of the sensor location (but without all the surrounding parts bolted in):
https://www.youtube.com/watch?v=FrPM31q_VC4#t=200.359982
- starting approx 3:18 into this video shows the coolant ...

ok ... after a 2 weekends delay (2 weeks ago replaced severe-leaking radiator in a 97 Grand Cherokee 4.0L, and, last weekend was too much snow on the ground) ... but yesterday I tested the fan low-speed power-circuit.

1st: tested the horn ... worked ... then swapped horn and low-speed relays ...

Thanks for above prior post from MattSrike for the link into the water pump options discussion ... good stuff
- note: if I determine I need to replace the water pump on this 94Bonne L27 then I may be back to this post with 1 more question on that,
since the RockAuto current photo of recommended ...

Thank you for that immediate-prior reply, especially "... low speed fans kick on (or, in my case, 1 of 2 fans) ..." and "... if you have no fans running 215*-225* at all, check out the low speed fan relay to confirm it is getting powered. Also, when it hits 225, and the main fan hits high ...

1 more post for today Tuesday 01/31/2017:

This is why I am looking at maybe the EGR flow-path to the intake being a possible problem (if the EGR flow is blocked)
for engine coolant overheat:

http://www.aa1car.com/library/egr.htm

Subject section:
"WHY EGR?
Exhaust gas recirculation reduces the ...

Thanks for all the replies ... here some more info and another question (regarding water pump impeller design):

I included a new radiator-cap when I replaced to a new radiator this past Summer
- the old cap didn't look bad ... but new is new ... and the radiator replacement detail specifically ...

94 Bonneville L27 naturally aspired engine:

Hopefully someone has had success with correcting a similar overheating problem since it doesn't make sense to me.

I don't put much mileage on this car (note: runs smooth at all road-speeds) ...
... currently it's something like 165K miles on the ...

ok ... so onto other higher-priority to-do items ... and I'll save hand-filing that support-arm near-contact point until the water pump needs to replaced in the future. Thanks for your feedback ... it lowers my concern-level regarding this situation.

Thanks for your interest, here you go - https://drive.google.com/folderview?id= ... sp=sharing

Slight correction to my last post: the near-contact point is the back (engine-side) of the pulley to the engine-support arm ... but ... not the curved part of that support arm but the flat-part of the arm that is against the engine ... and ... not for nothing ... maybe it's is my imagination (or ...

Thanks for reply ... no fuel leakage that I know of in the engine bay (took the fuel injectors out ~ 18 months ago and ran B12 Chemtool thru them with an ~ $10 home-made injector cleaner I saw on YouTube with a syringe and FI-connector and 9-volt battery and momentary push-swithch... cleaned-up the ...

Noticed this last week on my 94 Bonneville NA engine:
the water pump pulley is right next to the engine support arm where there is maybe less than thickness of sheet of paper between the 2.

I thought maybe a slightlly smaller-diameter (by ~ 0.25" or so) pulley would be the way to go ... so ... I ...

OK, before confirming the source of the gasoline odor I ordered the Dorman parts ... yes, as described the fuel return-line parallel to the fuel filter is severely rusted.

Today I get the P.S. rear up in the air and crawl under to confirm the fuel odor location.

Turns out I find an ~ 3/8" length ...

Thanks for the quick accurate info ... I am now going to order the Dorman parts #800-154 and #800-142.

For my 1994 Bonneville SE:
2 years ago I used Dorman #800-153 (3/8" diameter steel tube with compression fitting) and a tube-bender to near-exact replace the rusted-thru high-pressure fuel-line coming out of the filter ... this worked well.

Now, the parallel Return fuel-line (same location, under ...