Help needed! 99 STS
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Cadillac Seville / Cadillac Eldorado Forum Discussion, Help needed! 99 STS in Past Cadillac Vehicle Discussion; Hey guys, back again with a couple questions, first of all on the way home tonight I was waiting at ...
  1. #1
    codeywynne is offline Cadillac Owners Member
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    Help needed! 99 STS

    Hey guys, back again with a couple questions, first of all on the way home tonight I was waiting at a light and once the light turned green I hit the gas and the engine seemed like it was miss-firing/stuttering until I took my foot off the gas pedal, now it had done this before after a few weeks of having the car, but it never brought up any codes. Tonight was a bit different, it seemed like whenever I pushed the pedal in more then about 20% it would do the stutter until I backed off the gas again, and tonight it also made the service engine soon light come on so I decided to pull over and pull the codes, and what it came up with was the following:

    DTC P0372 IC 24X Reference Circuit Missing Pulses (Current)
    DTC P1611 Loss of CVRTD Serial Data (Current)

    Now this being my first cadillac Im not exactly sure about the codes, but tomorrow I'm considering checking the spark plugs to see if the ACDelco one's were used since the previous owner mentioned them being replaced, but would this cause this issue?

    On a side note, I posted a separate thread a few weeks ago about a turn signal issue, and haven't had a lot of time to explore the issue. But today I had some free time and I decided to dig into this issue and explore possible problems. I checked all the fuses that are related to the turn signals and all are fine, I also checked all of the grounds and no problems there. I also removed the front headlight to check the front socket for corrosion and it looks brand new, along with the back. Now I know I mentioned this in a previous thread but the issue Im having is the right side turn signal do not work when actived from the turn signal switch or the hazard light switch. The left side works with no problems.

    While looking through the car and trying to explore possible issues I was under the driver side dash and found a plug that was just hanging and not plugged into anything, I looked around for about 2 hours to figure our where this plug went and nothing....... So I was hoping that you guys might be able to give me some input, Im not positive but I'm wondering if this is related to the turn signal issue. Now the plug I found is blue, with a blue/white wire and a light grey wire.

    Also note on the plug it says 3 PED if this helps at all, I have looked through my service manual I bought online and could find nothing that helps me with this so hopefully someone will know where this goes.

    Photos of the plug.


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  3. #2
    Buster28 is offline Cadillac Owners Member
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    Re: Help needed! 99 STS

    I am looking at the turn signal schematic for my 00 ETC which is probably the same as your 99 STS. It shows that when the Turn Signal switch is in the neutral position the left rear and right rear turn signal conductors are connected together by the switch. Accordingly, when the Hazard switch is activated both the right rear and left rear turn signals receive power at the same time from a single Hazard switch contact. The left front turn signal receives power from a separate Hazard switch contact and the right front receives power from a separate Hazard switch contact. When the Hazard switch is activated the turn signal lamp power comes from the Hazard Flasher.

    The Hazard switch is effectively the same as putting the Turn Signal switch in both positions at the same time except the turn signals use a separate flasher.

    To start troubleshooting this problem check to see if the left rear and right rear turn signals flash when the Hazard switch is activated. The next step depends on the results of this test.

  4. #3
    codeywynne is offline Cadillac Owners Member
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    Re: Help needed! 99 STS

    Sorry should have been a bit more descriptive on the issue:

    1) When I activate the right turn signal from the turn signal switch neither the front or back right turn signal lights. When activated from the hazard switch only the left side front and back turn signal light up.
    2) Both front left/right park lights work as they should so the bulb is not bad, and I just replaced all the bulbs also.

    3) When the right turn signal is activated with the turn signal switch, I do hear the clicking, and can feel the clicking if I slightly touch the hazard switch. But the right turn signal does not show on the Instrument panel as it should, nothing appears.

    The left side works normally as it should, and all the fuses are good.
    Here is a wiring diagram for you if it helps.

    http://oi40.tinypic.com/4sfuyt.jpg

    It's a very large image so I wont post it here (1401x1600)

  5. #4
    JimD is offline Cadillac Owners Connoisseur
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    Re: Help needed! 99 STS

    Quote Originally Posted by codeywynne View Post
    ....DTC P0372 IC 24X Reference Circuit Missing Pulses (Current)
    DTC P1611 Loss of CVRTD Serial Data (Current)

    Now this being my first cadillac Im not exactly sure about the codes, but tomorrow I'm considering checking the spark plugs to see if the ACDelco one's were used since the previous owner mentioned them being replaced, but would this cause this issue?
    Fouled plugs would cause a misfire and that is not your problem.

    P0372; First thing I would do is check for corrosion or obvious damage to the two connectors on the drivers side of the Ignition Control Module (ICM). You are most interested in the 6 pin connector but inspect both of them very carefully. In fact, it would be worth the time to inspect all four connectors.

    P1611; Has nothing to do with engine operation.

    While looking through the car and trying to explore possible issues I was under the driver side dash and found a plug that was just hanging and not plugged into anything, I looked around for about 2 hours to figure our where this plug went and nothing.......
    That connector end is likely or even certainly the power lead for the courtesy lamp that is on the panel you had to remove to get under there.

    ----------

    Quote Originally Posted by Buster28 View Post
    I am looking at the turn signal schematic for my 00 ETC which is probably the same as your 99 STS.
    Not even close to being the same....

    ----------

    Quote Originally Posted by codeywynne View Post
    ....
    1) When I activate the right turn signal from the turn signal switch neither the front or back right turn signal lights. When activated from the hazard switch only the left side front and back turn signal light up.
    2) Both front left/right park lights work as they should so the bulb is not bad, and I just replaced all the bulbs also.
    I have read your two posts about the RH side turn signal/hazard lamps. My first reaction would be failed bulbs or corroded connectors or damaged wire harness. Has there been collision damage repair to the RH side of the vehicle?

    3) When the right turn signal is activated with the turn signal switch, I do hear the clicking,
    That 'clicking' is generated in your entertainment system (radio audio).
    ....and can feel the clicking if I slightly touch the hazard switch.
    That could be the power of suggestion at work. Your Turn Signal/Hazard Module (which is part of the Hazard Switch Assembly) is a solid state device. As in no moving parts.

  6. #5
    Buster28 is offline Cadillac Owners Member
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    Re: Help needed! 99 STS

    Well not surprisingly your STS is wired differently than my ETC, where did you come up with the schematic?

    The first thing I notice different is there is a single Turn and Flasher Module, so one widget is controlling both circuits. I also notice there is a mistake on the schematic, the Lt Blue conductor is labeled "Right Turn Out" is actually the Left Turn Out. The Dk Blue conductor is Right Turn Out and it goes to the under hood junction block and to the instrument panel. From the junction block it goes to the Right Front Turn lamp and to the Right Rear Turn lamp.

    Since the Right Turn Out signal from the Turn and Flasher Module controls the RH Turn Signal lamps and the instrument panel lamp the most probable reason your RH Flasher/Turn Signals don't work is a defective Turn and Flasher Module.

  7. #6
    codeywynne is offline Cadillac Owners Member
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    Re: Help needed! 99 STS

    JimD:

    Thanks for the clarification, I am no mechanic by any means nor do I try to be, but I do like to work on my cars myself if I can. But after thinking about it I thought I came up with the same thing as you noted, so I will check that today, thanks again guys, like mentioned in my first post this is my first cadillac and I love it and have no intentions of getting rid of it, so I guess it will just cost me to fix these things lol..

    Buster28:

    I came to the same conclusion but I just wanted some more input from somebody who was a bit more knowledgeable. Thanks again guys, you guys are life savers, I was really scared to pull the codes last night and see what was wrong.

    Oh and sorry I bought the manual online from here http://www.tradebit.com/filedetail.p...service-repair It does help a lot and has a lot of info on the car although some of the pdf files are screwed up but I can get past that.

  8. #7
    JimD is offline Cadillac Owners Connoisseur
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    Re: Help needed! 99 STS

    Quote Originally Posted by codeywynne View Post
    ....I bought the manual online from here http://www.tradebit.com/filedetail.p...service-repair It does help a lot and has a lot of info on the car although some of the pdf files are screwed up but I can get past that.
    That web site advertises their product as "This is the very same manual that your local GM dealer technician uses in repairing/servicing your vehicle." And that is total BS. The printed Service Manuals (published by Helm) cost in excess of $100 when new, and the digital (DVD) versions are slightly higher, if available. I have the printed version of the 1998 Seville Service Manual plus several other GM vehicles.

    GM does not publish schematic diagrams in the format you posted earlier. GM expects their dealer's service department folks to connect the dots between various interconnected system schematics; it's not difficult.

  9. #8
    codeywynne is offline Cadillac Owners Member
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    Re: Help needed! 99 STS

    Yeah I really didn't believe that but it does have a decent amount of info, although it does not have everything. I will look into a Helm manual, used. Or would you recommend another?

  10. #9
    MoistCabbage's Avatar
    MoistCabbage is online now Cadillac Owners 10000+ Posts
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    Helm is the best manual you can buy, they're the ones GM service departments use. You could also subscribe to alldatadiy, essentially an online version.

  11. #10
    codeywynne is offline Cadillac Owners Member
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    Re: Help needed! 99 STS

    Quote Originally Posted by MoistCabbage View Post
    Helm is the best manual you can buy, they're the ones GM service departments use. You could also subscribe to alldatadiy, essentially an online version.
    Thanks man, I will defiantly look into both!


    Anyways guys, I had a chance to look at everything noted here today and I checked all four connections and they all looked fine but I do have a question( I do have pictures as well )

    The drive side 6 pin connection looked fine and when looking I noticed the 6 pin connection on the driver side had 6 connection points on the inside while the passenger side 6 pin connection only had 4. Is this normal? So any more thoughts on what could be the issue?

    Driver Side


    Passenger Side


    And upon further inspection I decided to pull the plugs, and as I thought would be the case they used the wrong ones. So most likely within a few days I will be ordering 8 new ACDelco#41-950 plugs. Just to be sure this is the correct set right?


  12. #11
    JimD is offline Cadillac Owners Connoisseur
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    Re: Help needed! 99 STS

    Quote Originally Posted by codeywynne View Post
    ....Anyways guys, I had a chance to look at everything noted here today and I checked all four connections and they all looked fine but I do have a question( I do have pictures as well )

    The drive side 6 pin connection looked fine and when looking I noticed the 6 pin connection on the driver side had 6 connection points on the inside while the passenger side 6 pin connection only had 4. Is this normal?
    Yes.

    It is common to use a X number of pins connector and utilize fewer than X pins. There is no way a reasonable person could attach the connectors to the wrong side of the module.
    ....I decided to pull the plugs, and as I thought would be the case they used the wrong ones. So most likely within a few days I will be ordering 8 new ACDelco#41-950 plugs. Just to be sure this is the correct set right?
    Those are obviously not ACDelco plugs. ACDelco 41-950 is the correct plug.

  13. #12
    codeywynne is offline Cadillac Owners Member
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    Re: Help needed! 99 STS

    Quote Originally Posted by JimD View Post
    Yes.

    It is common to use a X number of pins connector and utilize fewer than X pins. There is no way a reasonable person could attach the connectors to the wrong side of the module.

    Those are obviously not ACDelco plugs. ACDelco 41-950 is the correct plug.
    Sorry about the mix up, I knew those were wrong just wanted to be sure that the ACDelco 41-950 were the correct ones so I was sure before ordering

    I was almost positive they didn't use the correct ones after seeing how the repaired some other things on this car even before pulling the plugs....

    Anyway do you think this could of caused those codes to come up when it stuttered/miss-fired. Or maybe a bad coil/module?

  14. #13
    JimD is offline Cadillac Owners Connoisseur
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    Re: Help needed! 99 STS

    Quote Originally Posted by codeywynne View Post
    I was almost positive they didn't use the correct ones after seeing how the repaired some other things on this car even before pulling the plugs....
    Now that is not a comforting revelation.
    Anyway do you think this could of caused those codes to come up when it stuttered/miss-fired. Or maybe a bad coil/module?
    If "this" means the Bosch plugs, I will say no. This is the first time you have mentioned "misfire" and you did not report a P0300 code.

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    basscatt is offline Cadillac Owners 10000+ Posts
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    Re: Help needed! 99 STS

    Quote Originally Posted by codeywynne View Post
    Yeah I really didn't believe that but it does have a decent amount of info, although it does not have everything. I will look into a Helm manual, used. Or would you recommend another?
    -------------------
    here ya go - less than $23 - including shipping -
    for both volumes - of the two volume set -

    http://www.ebay.com/itm/1999-Cadilla...edcaf7&vxp=mtr

  16. #15
    codeywynne is offline Cadillac Owners Member
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    Re: Help needed! 99 STS

    JimD:

    When I pulled the codes it did not come up with a P0300 but thats exactly what it feels like it was doing, I did mention it in my first post but after driving it today.. nothing. This issue didn't come up again, ran beautifully. But I'm not gonna trust that it wont happen again. The only codes that came up when this happened last night are the two I noted in my first post. But like I said I checked all the plug wires on the ignition coils and to the plugs and they look fine.

    I love this car but I got it cheap knowing I would have some things to fix, which doesn't bother me, it runs beautifully. Until this issue came up. But after I bought it I did have to replace the fuel tank because it was cracked and they tried to patch it with silicon thinking it would work. I just bought a used one from ebay and replaced the old one. Another thing I had to replace was the passenger side window regulator, and when I went to install another I noticed that they welded it to the door in place of a bolt Im sure because they were to lazy to find another bolt. But otherwise I am very happy, I will say that this is the nicest car I have owned yet out of the 3.

    basscatt:

    Thanks man, I appreciate that. I will order that on payday!

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