They have after market shocks and struts that use resistors to deal with the computer. I read online the car might not pass smog; this may be due to the computer, but I have not been able to confirm this. I bought replacements from a place in So. Carolina.
Problem with stalling on the '99 STS. I had the same issue with my '98; it's the crankshaft position sensors (it has 2). I spent LOTS of money fixing other could-be issues, and it was for sure the crankshaft position sensors. Since my repair, my mechanic has done 4 more of the same jobs, all on various 90's GM vehicles.
Seville overheating... most common problem... radiator cap.. really, that's it.. the pressure is too low and some escapes from worn down cap, lots of smells follow. Replace the radiator cap ($17 bucks). I did, and all these same issues disappeared!
The smell you are probably smelling is the valve cover gaskets. The back one was leaking on mine.
Antifreeze seeps down the head bolts, and eats up the threads in the block, so the bolts pop out.
I have the same problem with mine, so, if anyone knows anything, please answer... Thanks!
I work at a dealer, and have been a GM tech for 34 years. If that cars needs a set of head gaskets, take it to a GM dealer please. That is a big job, and very costly, and if you do take it to GM dealer, it will be done right. Thank you.
I work at a GM dealer, and it sounds like your heater box is not draining. Clean out the drain hole.
Have the ignition switch checked. When your keys are in the ignition, shake the key to see if the dash lights go on or off, or flicker. If they do, it's the ignition switch. I had a hard time convincing my mechanic, but after he replaced the fuel pump and it would cut out on me, he finally listened. I have not had any starting or stalling issues since replacing it. It's an old school lesson. Don't put any keys but your car keys on that key ring, or the weight of all the keys will wear out the switch.
Check the ABS wires that run to the front caliper - the clips come off & throw a code on my car every few thousand miles.
The problem with the 4.6 Northstar engine is the aluminum block. In order to torque the heads down properly, it takes a large amount of torque, and when the torque sequence is completed at the factory, the head bolts actually start to pull the block threads out a little bit. Since the engine is under intense heat and pressure, being crammed into the front of the cars with the entire transmission, the engine typically has a very short life. Most overheating problems start with either a small leak, crack, or damaged reservoir/cap. The mostly plastic, hard gaskets, that seal the four passages that are on the large aluminum coolant "H" pipe can disintegrate and leak as well.
Basically, the entire engine is going to overheat eventually, no matter what you think you can do. It's the most terrible design for temperature control that I've ever come across. It's not a question of if you have blown head gaskets, it's when... I have done more head gaskets on these Northstar engines than ANY other vehicles! Don't waste your money on these cars if they haven't gotten a head gasket overhaul, or if they run the least bit on the hot side of the temp gauge.
Had the same problem on my 99 STS. The rear shock bags were cracked (age) and the air ride compressor was working double time until it failed. I replaced the rear shocks with Monroe OEM replacement with electronic suspension and replaced the compressor. No problems now. The car sits up high and adjusts the level normally.
In reference to your 1999 Cadillac Seville STS.
I have a problem with the windshield wipers. The only thing that works is high speed wipers. No interval, no low or medium, and the windshield washer does not work either, in spite of the fact I just installed a new motor pump in the washer reservoir.
I have visited with 4 different dealerships in my area (south Louisiana) and no one can give me a clue as to what may be the cause or a diagnosis for repair. The answer is always, pay us 82.00 per hour, and when we find the problem, we will fix it.
I have found some windshield wiper modules online at reasonable prices, but I am not at all sure I would be getting the correct item for a good fit.
If you know the name and number of the module that will fix this problem, please let me know. If you have one to sell at a decent price, I would like to discuss it with you along with some advice for a fix for this problem.
The Caddy has only 75k, and I really do not want to trash it or sell it.
Thanks for the help.
Did you also get any dashboard blackouts?? I have the same problem, but now my dash acts funny.
It is called a camshaft position sensor. This will make your car stall out or not start at all if bad. Google how to replace it. It's not hard at all.
Had the same or similar problem, and changed my crankshaft sensor and did a lot of troubleshooting to find out that all I had to do was replace the ignition switch. It is a 20 dollar part and should take no more than an hour and a half. There are a few tricks to removing it, like holding the brake down when pulling a particular cord out. Can't remember specifically, but you can figure out if you try. Good luck.