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Need Help with 98 STS


n0rthstar

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Well I was out once again with my mom's 1998 STS, was running perfectly fine.

Stopped off to get a bite to eat, when I came back to it it would fail to start. Battery wasn't dead, it seemed to turn on fine but it wouldn't even attempt to turn over - it was as though I wasnt even turning the key.

Cleaned the key, heck, I've tried three keys so far.

After sitting in the car for about twenty minutes, just trying to turn it over again and again, it finally just started up and ran well - drove it for about half an hour.

Had to turn the car off again and left it for about 10 minutes. Returned to it, same thing. This time, thankfully, it only failed twice before starting up.

Got it home and since then it seems to start maybe two out of five attempts.

Ran OBDII and got the following codes the first time:

AMP U1064 (history) U1064 Loss of Communications with DIM

AMP U1128 (history) Loss of Communications with IRC

DIM U1016 (history) Loss of Communications with PCM

IPC U1301 (history) Class 2 BUS Shorted to Voltage

PCM P0741 (history) TCC System Stuck Off

TIM U1016 (history) Loss of Communications with PCM

RSS C1760 (current) LF Position Sensor Input Fault

RSS C1783 (history) ICCS2 DL Left Output Short CKT to GND

RSS C1785 (history) ICCS2 DL Right Output Short CKT to GND

RSS C1787 (current) Damper Control Relay Short to GND

Cleared codes, turned it off, failed, then started and ran it again, this time only got:

RSS C1760 (current) LF Position Sensor Input Fault

(which was expected, it is known for a while that the sensor is dead)

Repeated, this time I also got:

RSS C1760 (current) LF Position Sensor Input Fault

RSS C1787 (current) Damper Control Relay Short to GND

...So, could the Damper Control Relay Short to GND have anything to do with it?

Or does anyone else have an idea? I doubt it's a loose wire, else why would it fail, fail, fail, fail, start, without the car being moved or jerked (which would shake a wire into or out of place)... Could it be a faulty starter motor?.. I would have suspected a starter motor to either *work*, or *not work*, not this "fail/fail/fail/fail/start" business...

Help!

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Looks like you have bad contacts, gounds etc. Too many codes. Check the battery cables, contacts first, then grounds. Starters usually fail when the engine is hot (after driving say for 20 minutes). Because of bad connections starter does not get enough current to start a hot engine.

The saddest thing in life is wasted talent

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nOrthstar,

I have had the same thing occur on my 98 Eldo ETC previously. The cause was a dirty positive battery cable, at the battery. I reccomend that you disconnect the battery cables and clean them. Once finished coat the contact area with vaseline and tighten them down securely. In the event that this problem happens in the future, try wiggling the positive cable, or rotating it in the direction that tightens it. I am willing to be that your Cadillac will then start.

Best Regards, Alan Wise

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My approach would be a systematic elimination of the clean-up / maintenance items that should require no parts.

Disconnect the battery cables (negative 1st) and inspect for corrosion. Leave the battery disconnected.

Inspect and clean the battery negative cable end connector for corrosion where it bolts to the chassis.

Inspect and clean the large cable connection at the fuse / relay box under the LH side of the rear seat.

Under the hood, remove and clean the three large cable connectors under the red cover at the windshield end of the fuse / relay box on the RH fender well.

Connect battery cables (positive 1st) and see what is different (if anything).

You are looking at one hour (or less) labor that will eliminate potential nuisance problems. Good luck with it.....

Jim

Drive your car.

Use your cell phone.

CHOOSE ONE !

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I agree with everyone in that you should start with the easiest, most obvious culprit .... namely, battery, terminals, and cables.

Having said that, my 99 died without cause, and it turned out to be an ignition switch with a failed circuit. Switch was $100, plus removal and reinstallation.

1989 FWD Fleetwood, Silver

1995 STS Crimson Pearl on Black leather

1997 STS Diamond White

1999 STS Crimson Pearl

2001 STS Silver

2003 STS, Crimson Pearl

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Thanks for the input guys.

I somewhat doubt that it would be caused by the connections at the battery terminal as the rest of the car operates fine - blower, cd player, obd, etc, they all work perfectly. As i said, the car itself will turn ON, the engine, however, will not turn over - or attempt to.

This has happened while the car is at ambient temperature (i.e. has not been driven for an hour or so), as well as when it is hot (after, say, a 20 minute drive)

The most likely culprit, from what you have all said, seems to me to be the failed ignitor switch - could this be so?

I would assume that, had it been a bad battery connection, the power to the rest of the car would not have worked as well, i.e. the HVAC, Amp, display,etc. Any input as to this thought?

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I don't know if it would apply here, with a Cadillac, but I had a similar problem once. I used to own a '74 Chevelle, a long time ago. It had the same problem, would run fine, shut it off, would not start, after a while, would start. Ultimately, after many new parts, it was a frayed, and shorting wire to the starter. Replaced the wire, it never happened again.

Don

"Modern warriors saddle iron horses of chrome."

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Any and all other vehicle electrical systems can be considered "low current draw" when compared to the starter motor.

It's your money. Go ahead and throw that money at the key switch after you have eliminated all the other no-cost possibilities to your satisfaction.

The key switch for my '98 is operating perfectly at 144,xxx miles and who knows how many engine start cycles. But the switch can fail.

I'm on your side and waiting to hear about the fix.

Jim

Drive your car.

Use your cell phone.

CHOOSE ONE !

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<<I somewhat doubt that it would be caused by the connections at the battery terminal as the rest of the car operates fine - blower, cd player, obd, etc, they all work perfectly. As i said, the car itself will turn ON, the engine, however, will not turn over - or attempt to.>>

This is exactly what the symptoms are on the 94 to 96 Northstars, where the battery had two cables on the positive post, ONE for the accessories, and ONE for the starter. Corrosion caused the connection to the starter to fail!

I am not familar with the 98, but I surely wouldn't make any assumptions. Is your battery under the back seat?

Jim in Phoenix

Jim in Phoenix

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Ditto, clean those cables first! Take the positive cable apart by pulling off the red insulator and clean inside, watch how it comes apart so you can get it together. If there is a washer watch where it goes... This is always the first place to start

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I'd say check the battery cables too.. however if this does not fix it try to listen. What I mean by this is the same thing happened to my dads STS. Turned out it was the fuel sending unit in the gas tank. Try listening to see if when you turn the key to on does the fuel system pressurize?

Cop didn't see it, I didn't do it!

93 STS 225,000 Miles

99 STS 111,000 Miles

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Hi again

This is nOrthstar's dad and I think I should point out that when the problem he describes happens there is virtually not a sound when you turn on the ignition key yet power elsewhere abounds. A new battery was put in last December and all was well until this problem occurred in March only to go away until this past Saturday when it returned for only a day. Touch wood the car is once again starting fine.

Do you think this could be a transmission gate problem?

I have heard that the car will show absolutely no signs of power when turning the ignition key on if it is sensed that the car is not in gear (even if it is).

Can anyone verify if this is true.

Thanks

Paul

PS All power connections that I can see look clean and secure

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Not sure I am following you completely but if the PRNDL (neutral saftey) switch is out of adjustment or inop, the PCM will think the car is in gear and will not even crank. Did you try wiggling the shifter while attempting to rank?

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I somewhat doubt that it would be caused by the connections at the battery terminal as the rest of the car operates fine - blower, cd player, obd, etc, they all work perfectly. As i said, the car itself will turn ON, the engine, however, will not turn over - or attempt to.

I just did the exact same thing to my 98 STS, and that is what was wrong!

Big Jay ;)

Life is too short to grow up!

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