Don't know if air suspension is working on 1999 buick lesabre

the spark plug tips will look , LIKE A HORROR
on the offender cylinder.
there is one good sign
and USA ? car, the OBD2 scans show the leaking
cylinders are gross misfire DTC error P030x
where tells witch cylinder is getting wet. (called misfire)
the bank leaking OBD2 fuel trim way off the scale.

radiator leak down test Fails. (a tool with same name)
first off the gasket would have to be a double failure
to leak to intake runners, water side to air side

there are 2 parts, here the plastic top and aluminum main
bottom intake manifold.
evidence 2
if the gasket leaks below the HLA Lifter area gets wet .
and the engine oil looks just like chocolate milk shake.
nasty oil , MILKY for sure.
if the wet ports fail water hits the pan too.

also is not the upper plastic side, dry.
and only bottom is coolant wet.

see my threat vector photo
as you can se , it be a double failure of the gasket
if sucking oil see white smoke at tail pipe end
or see steam from water (coolant burned) same place.

cross over year models
might be cosmetic changes
you would have to check the yersa suspensions parts listing

• Seventh generation (1992-1999)
• Eighth generation (2000-2005)

http://www.wholesalegmpartsonline.com/cars/buick/0/lesabre/accessories---body/lesabre-parts.html

Jim, Remove passenger side kick panel to access the fuse box where horn fuse is located #3 fuse in your manual, box fairly high up under dash. Horn relay under hood/engine compartment fire wall.
Check the attached links,instruction and guides and a manual for your buick, Good luck
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Interior Fuse Box Location 1990 1999 Buick LeSabre 1992 Buick LeSabre...
Troubleshooting broken Horn or fuse or relay GM Buick LeSabre 1994 1995...
http://pdfstream.manualsonline.com/8/81776d98-998a-493c-aac6-a5895c51d47b.pdf
Horn doesnt work Ricks Free Auto Repair Advice

My air lines were shot ant the pump quit. Check for air leaks and yes you can shut it off but the air shocks will not work any more. I bought after market air shocks which has their own air lines you pump up like you do your tires. I check mine every three or four months.

Do some additional research, but they sell a lot of Climate Controls on ebay. 1995-1999 Buick Lesabre, Riviera, Park Ave Digital Climate Control P/N 16181974 (Fits: Buick LeSabre)

I have a 2003 Buick lesabre limited my inside lights don't work

you can unplug the pump in the back,. if your car has coil springs in the rear you can get standard suspension struts and replace the air struts with them.

1999 Buick LeSabre Custom Front and Rear Tires P205/70R15
1999 Buick LeSabre Limited Front and Rear Tires P205/70R15
1999 Buick LeSabre PP (*) Front and Rear Tires P215/60R16

(*) PP = Performance Package

Other details can find in the Buick-Lesabre-Owners-Manual

Hope helps (remember rated and comment this).

take it have theme read the codes maybe a vaccum leak,mass air flow sensor,egr valve could be numerous things the code will tell you

The coil is on top of the engine and the module on the firewall or suspension strut tower