2000 STS - multiple DTCs
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Cadillac Seville / Cadillac Eldorado Forum Discussion, 2000 STS - multiple DTCs in Past Cadillac Vehicle Discussion; Hello all, I am looking for some expert help and I know I can find it here. I am a ...
  1. #1
    Rick88 is offline Cadillac Owners Member
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    2000 STS - multiple DTCs

    Hello all,

    I am looking for some expert help and I know I can find it here. I am a mechanic
    (aircraft/my own vehicles/etc) for 30 + years but this cadillac is a whole new animal that I am looking into. I am trying to help a friend with her cadillac, it is a 2000
    STS and the airbag light is on, the ABS light is on and also the Traction light stays
    on and the service engine soon light was on. She said something is running the
    battery down overnight as well, I did have to jump it this morning. I pulled the
    codes with an OBD II reader and they were P0340 and P0385, I pulled the codes
    from the DIC and it showed 2 current codes; ABS C1232 and IPC U1000. I erased
    the P codes yesterday and drove the car to work and back today (about 65 miles
    round trip) and the service engine soon light is still out, but I do still have the ABS,
    airbag, and traction lights on all the time. Any guidance in these matters would be greatly appreciated.

    Rick

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    Ludacrisvp's Avatar
    Ludacrisvp is offline Cadillac Owners Connoisseur
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    Well you aren't in the correct sub section of the forum. But I know that a weak battery can cause lots of random codes and issues to come up. The battery as you may have noticed is under the back seat cushion (just pull up on it and it pops off) and is a vented battery if you don't get the right kind you will cause the seatbelts and the seat bottom to breakdown from the acid fumes.
    It may or may not fix the issues but it's a start.


    Sent from AutoGuide.com App

  4. #3
    MoistCabbage's Avatar
    MoistCabbage is online now Cadillac Owners 10000+ Posts
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    A bad battery can definitely cause random/false codes. Make sure you don't have a low voltage problem first.

    Please list the code definitions, we don't quite know them all by heart yet . . ABS and TCS lights together are usually a wheel speed sensor.

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    Submariner409's Avatar
    Submariner409 is offline If it won't run, stick on fender vents
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    Re: 2000 sts

    Moved from the new 2005+ Sigma body "STS" to the Seville forums.

  6. #5
    Ranger's Avatar
    Ranger is offline Cadillac Owners Member
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    Re: 2000 STS - multiple DTCs

    Forget the code reader and just use the DIC. It'll be more accurate.

    If you suspect a current draw connect a test lamp in line and start pulling fuses until you find it.

    P0385 looks familiar. I think that may be a CKP sensor. P0340 may be related as well, but I can't remember for sure. The code definitions you post will tell, but GM had a bad supplier from 2000+2003. They all need to be replaced eventually.

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    Rick88 is offline Cadillac Owners Member
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    Re: 2000 STS - multiple DTCs

    Okay, update. The P 0340 code did not come back after clearing it, I think because the starter solenoid was acting up and it wouldn't start for a couple of tries, then it started fine. Cleared that code and it's good. I still have the ABS C1232 code for left front speed sensor short-circuited or open. Also have the IPC U1000 for class 2 communication malfunction. I am getting 2.0-2.3 volts to speed sensor (same as right side) so I tried another hub assembly (from junkyard), same results. Can anyone share a diagram of that system with me? If this was my vehicle I would subscribe to all data but just trying to help a friend.
    Thanks,

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    Ranger's Avatar
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    Re: 2000 STS - multiple DTCs

    Are you looking for a diagram or a wiring schematic? I can post a diagram.

    There IS a possibility that the junkyard hub had a bad sensor as well. Did you check continuity on either of them?

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    Rick88 is offline Cadillac Owners Member
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    Re: 2000 STS - multiple DTCs

    Ranger, yes sir, I checked continuity on both of them and none present on either. I wanted a schematic to see how the system works for myself, had a friend say there had to be voltage going to it but I figured a sensor circuit should have continuity at all times if the sensor was good. Any insight is appreciated.
    Thanks,

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    Ranger's Avatar
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    Re: 2000 STS - multiple DTCs

    I figured a sensor circuit should have continuity at all times if the sensor was good.
    That is starting to jog my RAM. I thought the same thing, but now that you mention it, I think I recall a discussion about this not to long ago and I was corrected. Can't swear to it, but you may have to spin the hub to get continuity. Don't ask me to explain it.

  11. #10
    JimD is offline Cadillac Owners Connoisseur
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    Re: 2000 STS - multiple DTCs

    Quote Originally Posted by Rick88 View Post
    Ranger, yes sir, I checked continuity on both of them and none present on either.
    No continuity = two bad sensors. Measured with the sensor disconnected from the vehicle wiring.

    Basically, the wheel speed sensor is a coil surrounding a toothed magnetic rotor. The rotor teeth impose a series of low voltage pulses as the hub rotates. The EBCM counts the pulses and calculates a wheel speed value.

    No continuity means no pulses = a DTC for that wheel speed sensor.

  12. #11
    Ranger's Avatar
    Ranger is offline Cadillac Owners Member
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    Re: 2000 STS - multiple DTCs

    So we ARE correct in assuming that there should always be continuity? I just changed one for JimmyH and I think there was no continuity on the bench and it was a brand new unit.

  13. #12
    JimD is offline Cadillac Owners Connoisseur
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    Re: 2000 STS - multiple DTCs

    Quote Originally Posted by Ranger View Post
    So we ARE correct in assuming that there should always be continuity?
    The wheel speed sensor circuit external to the EBCM is about as simple as a doorbell. Find it under ANTILOCK BRAKES in the Service Manual.
    I just changed one for JimmyH and I think there was no continuity on the bench and it was a brand new unit.
    No continuity on a new unit makes me suspicious something else was happening there; bad ohmmeter connections or faulty ohmmeter or failed ohmmeter battery or pilot error. Or something.

  14. #13
    Rick88 is offline Cadillac Owners Member
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    Re: 2000 STS - multiple DTCs

    Thank you gentlemen, I will back track and double check it while spinning the hub. I had previously checked for continuity statically. Thank you all for the help, I will report findings.

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