STS Electrical System (1998)

[pats37]

No error codes whatsoever. Crank sensors were replaced even though no error codes. The problem is the same and it is intermittent and dangerous.

The car just dies (while driving or idling in driveway) Sometimes it starts back up and other times it goes through a litany of crazy events such as resetting the display avg. mph, sends a warning "service air bag" blinks or puts out the fog lamps (which I keep constantly on) keeps restarting airbag motor, lights the idiot lites but not the display, loses all power to dashboard another time. if you just sit there sometimes with the ignition key on but not cranking it will give you a show until it eventually resets itself. Sometimes while the key is left on and sometimes if you turn it off for a few minutes.

If there are any astute electrical system trouble shooters please help.

All of the fuses are good.

Is there a self-resetting circuit breaker somewhere in the system?

How can you diagnose an intermittent problem on a relay?

Is there a short on the system? If so, where would you look? All wiring appears fine, no bare spots or cracked insulation is visible.

Relays on electrical block under rear seat run hot but this may be normal. If you tap them they don't change state or cause any problems. The problem comes back when it feels like it.

We're still working on it but could use some help or ares to troubleshoot.

TIA

Pat

[Northstar]

Did you replace the ignition switch yet? try to wiggle the key while its running and see if anything happens. Also check battery cables.

[adallak]

bad ground?

[pats37]

Did you replace the ignition switch yet? try to wiggle the key while its running and see if anything happens. Also check battery cables.

The ignition switch checked out good. There was a loose harness clip on the back which was repaired and put in place. We thought that was it, then 3 weeks later the same problem came back. I dont think it's the ignition switch because when the dash lights go dead you can still crank the starter. The car just wont start. This would also indicate the battery and ground are ok too. They are tight, no corrosion.

You can continue cranking the starter forever, but until the dashboard comes back and resets itself and display text of __._ avg. mpg, the car won't start. When everything comes back and you hear the five chimes it will turn over like nothing ever happened. Sometimes when it goes haywire it resets the avg mpg to 0.0 again.

Another weird thing that happens is sometimes while driving the windshield wipers and washer won't work. Three or four minutes later everything works fine. The wiper problem never caused the car to lose power though. It may be a separate problem.

The strange thing is that everything works fine until it decides to screw up.

Frustrating.

[Logan]

You need to check every ground on the car. This will take awhile.

You need to inspect both ends of both battery cables.

Could be a bad ignition switch. I have heard of that.

Could be a bad battery.

All of that needs to be checked before checking anything else. Could be a bad computer on the Class2 data network. Could be...but you have to check all the listed stuff first.

[pats37]

Logan,

Thanks, I will replace the battery just in case. The car only has 24k miles on it and has been garage kept. It looks brand new. But the battery is 6 yrs. old.

Hell, I've already replaced two crank sensors at a cost of close to $300.00.

The mechanic (independent shop) is good and has checked for loose grounds. I will have him remove and inspect and clean both ends of the main cables when installing the new battery.

Is there a diagnostic test that can be performed on the ignition switch?

Thanks for your help.

Pat

[Bob D]

The mechanic (independent shop) is good and has checked for loose grounds. I will have him remove and inspect and clean both ends of the main cables when installing the new battery.

Grounds can be tight and still not be grounding properly, caused by corrosion. This will create a high resistance 'ground', which on a system like a Cadillac (with many grounds) can create 'looping' as the circuts continually and redundantly search for the path of shortest resistance. This phenomena can wreak havoc on senstive systems like the Cadillac's. As Logan advised, try to locate every gound, and check not only for tightness, but cleanliness as well. A small wire brush and some contact cleaner can be real handy for cleaning ALL surfaces, including brushing to shiny bare metal on the frame, bulkhead, or where ever. Good luck!

[pats37]

Bob,

Thanks. My mechanic said the same thing as you and pulled the electrical clips apart checking all he could find. I can't be sure if the took apart and checked the main battery cables but that will be done tomorrow when I have them put in a new battery.

If you have any advice on a location that could be missed (ground) let me know. I have found him to be quite competent but anyone can miss something on a Cadillac. Unfortunately my local dealer is among the less competent ones.

They pulled the computer (located in the air filter housing) and checked all connections and relays. They pulled the relay and fuse blocks in the engine compartment and rear seat and checked all connections and relays.

I'm hoping that it may be a problem inside the existing battery. (Is that possible?)

I appreciate everyones input and will keep everyone posted as to the final outcome. I like this car so much I'm keeping it when I buy another. I will see this thru to the end.

Pat

[Logan]

My 2001 Deville had a bad battery....I actually still have it here....it still a has green eye after sitting on the floor for a year.

I would be suspect of a 6 year old battery. The cells inside can go bad....

Cadillacs are very sensitive to....

Good batteries.

Good grounds.

Clean battery cables.

Any problems with these...can cause major bizarre problems...

[Bob D]

Bob,

Thanks. My mechanic said the same thing as you and pulled the electrical clips apart checking all he could find. I can't be sure if the took apart and checked the main battery cables but that will be done tomorrow when I have them put in a new battery.

>I'm hoping that it may be a problem inside the existing battery. (Is that possible?<

Yep, it sure is possible. Like Logan said, Cadillac's electrical systems are VERY sensitive. Even a battery that will turn the engine over can caused intermittent glitches, especially an older one. Replacing it it one of the first things I would do with the symptoms your ride is having.

[pats37]

Bob,

OK, here is where we stand.

1. New crank sensors installed.

2. New battery (today)

3. Main power cables cleaned and reinstalled.

4.All harness connectors checked.

5. All relays checked.

6. Ignition switch checked.

7. All connections to computer, fuse and relay boxes in engine compartment and rear seat checked.

Final result: Problem happened again on my way home!!

I parked at the liquor store on the way home at a slight downward incline. Came out put the ignition key in to start, NADA. Turned it of, opened door (so radio would go off-standard) and turned key to on position without engaging starter.

Then just watched the display go through its little light show--engaging air bag motor, blinking the dashboard on and off, sending me a "service airbag warning", shutting down down, coming up again, then finally the 5 chimes after the default of avg, mpg. came up and it started. I then went home, poured a drink and said "GOD! DID I SOMEHOW PISS YOU OFF WITHOUT KNOWING IT?"

I will call my mechanic again monday and I know he will be absolutely beside himself. He has not even charged me for many of the hours he has into this problem.

I cant believe that my next move is to replace the entire wire harness. crap! I'm not even sure that will work! This car ran fine for 5 years! Ever since the last rear end hit (which only cost $950.00 to repair) I've had these problems. I've already spent about $600.00 trying to fix it. The money is secondary at this point.

I need a solution. If anyone can help, please do. I love this car and don't want to trade it. Besides, that would be dishonest as someone else will inherit the problem.

I still appreciate everyones help so far, but this one is a beauty.

Pat.

[pats37]

Logan,

I notice you post on other boards. I would appreciate your opinon after reviewing my previous posts and the last one today.

Bear in mind that this is a "garage kept" lightly used vehicle. 24,475 mi. A 1998 STS with everything but moonroof. My mechanic commented it is "showroom condition".

These problems occurred only after I was rear-ended by a furniture truck at a stop light. The damages to the rear didn't even involve the bumper cover, only the energy absorbers and a tail exhaust fixture. Total damage paid by the insured was about $947.00.

The problem started just after the repair was completed. They never disconnected the battery for the repair. (I asked). I just bought a new battery anyway.

I can't imagine (nor can my mechanic) what could cause this problem besides an electrical one. There are "no codes" and no past frames of codes.

Why would a car that has run perfectly for 5 years all of a sudden develop this problem? My mechanic was a "top" certified Toyota mechanic before he started his own business. He goes to many of the continuing education seminars and has highly trained people in his employ. His equipment is up to date as is his education. And he is honest and down to earth (rare).

I'm convinced this problem is something that has been either overlooked or not investigated thoroughly. If you can help, please do.

Thank you.

Pat

[Bob D]

These problems occurred only after I was rear-ended by a furniture truck at a stop light. The damages to the rear didn't even involve the bumper cover, only the energy absorbers and a tail exhaust fixture. Total damage paid by the insured was about $947.00.

The problem started just after the repair was completed. They never disconnected the battery for the repair. (I asked). I just bought a new battery anyway.

pat, how long ago was that rear-ender, and how many miles/time have elasped since the symptoms appeared? I'm not sure about your '98, but my '93 has a lot of electronics/leads and grounds in the trunk, on both the rear bulkhead behind the seat, and the side panels, especially the left (drivers side). If you haven't already, I'd refine my investigation to those areas. It wouldn't take much (scraped insulation, shorting wire, conductive debris in a connector panel or the underside of a fuse box), to trigger these intermittent symptoms.

I feel for you man, hang in there.

[Northstar]

My next step would be to replace the ignition switch.

[franey]

First I think you have done some fine detective work, but you failed to tell us the part about the wreck. NOW , why is that important, well for one thing you mentioned the tailpipe work. Well the electrical ghost you are looking for was probably caused by the electric welder they used on the exhaust, A good body shop always disconnects the battery before cranking up the electric welder, because you ground to the car and then your electic arc goes to the ground. Body shops found out years ago that this sometimes and i repeat sometimes would cause a computer failure or computer screw up. Now with all of the the onboard computer type units that your cadillac has on board , you could have one that took a hit when they used an electric welder somewhere on it while they were fixing it, although it did not knock it out , it is no longer right in the head , hence your intermittent problems. The shop manual i have for my daughters old ACURA, had a bold print area that stated to NEVER USE A ARC WELDER WITHOUT FIRST DISCONNECTING THE BATTERY, TO PREVENT ELECTRICAL DAMAGE. From what you have described and what you have done , I bet you have a controller that has taken an electrical hit, here again this is just a theory, but it is possible . GOOD LU CK

[an01sts]

Just some food for thought: My 99 STS had a recall on the ignition switch.

[pats37]

Bob,

Accident occurred on 5/19/04. The car was repaired on 6/4/04 and had 23,127 mi. on it. It has about 24,450 now. The problems started after the repair. I went back to the body shop and they had the "caddy expert" look at the car. He thought that it might be the EGR valve but said that maybe some carbon particles shook loose and would eventually blow out. The initial problem was only hard starting but if I turned the key off waited 15 seconds then depressed accelerator to floor and released then it started all the time. The current problem evolved over the time period to current day. Right after the accident I had none of these current problems. the progression ran from the original problem to stalling while driving (mostly on hilly terrain)(like someone reached over and turned off the ignition),

difficulty starting regardless of pedal depression and stalling while driving, all of the previous plus "service airbag warning" and taking much longer to start. Now all of the foregoing plus the light show on occasion. It hasn't stalled while driving lately but I won't swear it wont happen again. I'm not driving it as much because of the problems.

I don't think my mechanic has removed the trunk panels yet but I will know monday. If not you can bet that will be the next move and I will stay there and watch. I appreciate your help and concern. Thanks.

Pat

[pats37]

Northstar,

Thanks, I inquired about that in detail. The mechanic said he highly doubted it and he knows his "stuff". In any event if it comes to that it will have to be done by cadillac at a cost of about $400.00. I will exhaust every other possibility before resorting to that.

Pat

[pats37]

Franey,

Very interesting, thanks. Early on in this problem I asked the Body shop manager who I have known for 25+ years if he had to disconnect the battery for this repair.

He said no which made sense since the clock had the correct time. (they rarely take the trouble to reset the clock). I asked the question in relation to the problems thinking that maybe the computer needed to be reset or something.

The only tailpipe damage was the chrome exhaust extension which was replaced ($151.19). I do not know if it is welded or bolted. I asked specifically about the exhaust system because I was concerned about possible damage to the cat converter. They said they checked it out and only the extension was damaged.

You can bet that monday morning that question will be first on my list. I know I will get the truth from him based on our long friendship. That is a very good point and well worth exploring. Thanks again.

Pat

[pats37]

Franey,

One more point. The only parts replaced as a result of the accident were the exhaust extension and one energy absorbing bar. The rest of the bill was labor and painting and refinishing of the rear bumper cover.

Pat.

[franey]

THE extension is welded on , now if he used acetylin torch to weld it back on then you can disregard post, but if used electric welder and grounded to exhaust system you have at least three exhaust sensors in exhaust system that all lead back to computer with read outs. The entire exhaust from the back manifold back is welded togher once it leaves the back exhaust. I remembered my old Saab mechanic and called him about your problem and he reiterated what I have said , he was taught as a Factory trained mechanic to NEVER use an electric welder on the Saab cars without first disconnecting the battery, too much of a chance that the electric welding current winding up in the wroung place and zapping the computer. Here again chance not a definate , but he refuses to take a chance and always disconnects battery.

[pats37]

Franey,

Spoke to body man today. The final chrome ext. is a mechanical connection. Told him why I asked because of the problems which I really thought were solved a lot earlier. His welder, when needed, is an experienced guy who never welds anything on a car without disconnecting the battery and only uses an "earth" ground in the shop itself.

He is surprised also but has buddies who are experienced mechanics in electrical systems and will run the problems by them for me.

Bob,

Yes, the trunk panels were removed early on and inspected by his mechanic but he will do it again himself just to be sure nothing is missed. However, I can't get back in til next week. He is totally booked but will sneak me in early in the week.

Northstar,

He is sure the ignition switch is good, when he had the car apart (console and radio removed) he checked it out himself. He agrees that it is a "ground" problem, but where?. I know him, he will be thinking about this all week. He won't give up, he just has to figure out where to look.

Again, thanks to all. Sooner or later ( and I certainly hope sooner!!! ) this will get resolved. The final cost is yet to be known. This is a nightmare for all involved. I'm glad to have caring "friends" along the way. It means a lot to me.

Pat

[PAUL T]

A factory service manual should tell you where all the grounds are located. If you have access to one you might check there or maybe someone on the board can scan and email you a copy of the diagram.

[pats37]

Paul,

Thanks for your input. Good point. If anyone out there has that info it would be appreciated. My email is pats37@aol.com and my Fax is 518 587-1710.

I don't think my mechanic would need it, but I would like to have it. I'll gladly pay for it too. There are so many people trying to help I'm sure the problem will eventually get solved.

Sometimes I wonder if the rear-ender was just a coincidence, and the problem just developed. But it's like a virus, constantly changing as things are done.

Frustrating.

Thanks again to all. The internet is a great thing.

Pat

[pats37]

Just in case anyone is interested, there was a cadillac memo regarding deterioration of the ground from inside the right frame rail to the alternator. This was also removed, cleaned and checked and was ok. The saga continues.

Pat