20th Apr 2011, 15:35

Bad sensor, my 1998 STS does the same, keep driving.

23rd May 2011, 16:25

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.

22nd Jul 2011, 12:24

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.

26th Jul 2011, 17:49

Did you ever find out what was the problem?

30th Aug 2011, 19:58

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!

12th Sep 2011, 08:13

The smell you are probably smelling is the valve cover gaskets. The back one was leaking on mine.

15th Oct 2011, 16:38

Antifreeze seeps down the head bolts, and eats up the threads in the block, so the bolts pop out.

6th Jan 2012, 17:04

I have the same problem with mine, so, if anyone knows anything, please answer... Thanks!

31st Mar 2012, 19:29

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.

31st Mar 2012, 19:36

I work at a GM dealer, and it sounds like your heater box is not draining. Clean out the drain hole.

30th Jul 2012, 00:57

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.

23rd Dec 2012, 14:18

Check the ABS wires that run to the front caliper - the clips come off & throw a code on my car every few thousand miles.

12th Jan 2013, 14:41

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.

13th Jan 2013, 08:30

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.

11th Mar 2013, 19:22

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.


21st Jun 2013, 19:26

Did you also get any dashboard blackouts?? I have the same problem, but now my dash acts funny.

Thanks... jmullengtr@gmail.com

16th Aug 2013, 22:16

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.

17th Feb 2014, 08:18

There are two hoses that clog up.

25th Jul 2014, 23:02

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.

18th Oct 2014, 03:25

Well of course I was googling to find out more about my Caddi problems, and after googling I ran across numerous different sites about these Northstar engines, and one thing that seems to happen to them all in a row is... radiator, water pump, thermostat, and head gasket.

Well I bought this car 6 month ago, and it's still being paid for. So far I have liked it all except well my car needed a new air shock... and then well of course... my radiator started leaking. Found out it was bad to begin with, and someone puttied the hole, but I replaced it nearly a month ago.

Then I noticed the two quarts of oil missing all the time??? Just about every time I check it's low... And today I ran a lil hot, stopped in McDonalds parking lot, and realized the water was extremely low??? No leaks though, so I was like where's it going? I checked the oil, no signs of water, so thought it wasn't a head gasket, but that was not completely ruled out. After hours of looking, I find out my thermostat housing seals are leaking and the water pump is squirting water, which means that it's going out. So... I guess after fixing that, it will be my head gasket. Wow, what a crazy, crazy way that a lot of people have it happen in that order!!! I wish mine had a recall on it ha ha ha. I'm thinking about not fixing those problems and taking it back to see if I can a trade to a different car, and well I just got a call from my hubby, and now my husband's Dodge ram is having problems also... so UGH the problems never seem to end.

11th Aug 2015, 22:53

My 99 STS had the same problem, ABS and traction control lights on. The EBTCM (electric brake traction control module) is located left front under the hood below the air cleaner. The module has a ground peg coming from it that connects to a chassis ground. This connection corrodes! Clean it and make sure all is good, and all will be back to normal.

17th Aug 2015, 14:13

Allen, I see you posted this problem regarding your wipers in June of 2010. I am having the exact same problem with my '98 SLS with only 45k miles on the odometer. What turned out to be the cause of your wiper problem and how did you resolve it. My email is 66luxuryliner@bellsouth.net if you wouldn't mind letting me know. Thanks, Greg.

8th Sep 2015, 04:17

It is the radiator cap. Buy a new one and all should be fine. That's what I did for mine; the gasket in the cap was bad.