2002 STS, won't crank, engine does not turn over
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Cadillac Seville / Cadillac Eldorado Forum Discussion, 2002 STS, won't crank, engine does not turn over in Past Cadillac Vehicle Discussion; 2002 Seville STS - When the key is turned to the start position the starter/engine won't turn over. Dash lights ...
  1. #1
    ot1
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    Question 2002 STS, won't crank, engine does not turn over

    2002 Seville STS - When the key is turned to the start position the starter/engine won't turn over.

    Dash lights go completely black when the key is turned to the Start position and relight when key is released.
    This is not my car so I am unfamiliar with the dash lights going black, maybe this is normal when starting this car.

    When the dash is lit up the transmission gear shift indicates correctly for each gear on the dash.

    Voltage measured at the terminal post located at the rear of the engine compartment's fuse box and engine ground strap is 12v when turning the key to start.

    Relay number 36 (Start 1) in the engine compartment's fuse box was tested good(coil and contacts) when removed. I cannot feel this relay pickup when key is in the Start position.

    When relay 36 is removed I can jumper the appropriate terminals on the fuse block and the starter will crank (only jumpered it for 2 seconds, a couple of times). Vehicle will start and run with the key in the run/on position if cranked for a few more seconds.

    The relay 36 terminal on the fuse block, closest to the fuse removal tool gives me a 1.2 ohms to ground. The terminal diagonal the relay coil ground terminal is open when the key is in the Start position.


    So I need someone (Mark C.?) with the wiring schematics that can tell me where this terminal is connected to/traces back to.

    There are no DTCs stored and the Service Engine light is off. The dash Security lamp only lights for a second when I first turn the key on.

    I'm thinking its not the neutral switch/range switch unless there are two functions to this switch since the dash gear shift indicator is operating correctly. Where is this switch located? How many terminals are on it? How would I access it.

    Thank you.

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    Submariner409's Avatar
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    Re: 2002 Seville STS, won't crank, engine does not turn over

    12 volts is a dead battery. It should read 12.4 to 12.6, engine OFF. Begin by checking all 4 battery cable ends for clean, tight connection. Especially the ground cable to the floor pan under the rear seat. The starter positive cable goes under the intake manifold just in front (radiator side) of the P/S pump - you might carefully pull on that while someone tries to crank the engine (starter motor connection loose ?) - hope that it is not the positive cable stud terminal on the starter motor - the intake manifold has to come off to tighten that.

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    ot1
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    Re: 2002 Seville STS, won't crank, engine does not turn over

    Since since this is lead acid battery, a battery having only 12v is OK, maybe not fully charged, but neverthe less sufficient to start the vehicle, and its not dead. A dead battery would read a multiple of 2.0v per cell less than 12v. (ie 10v = one dead cell, 8 v. = 2 dead cells, and so on). The point being that battery/ground strap corrosion is not the issue for this vehicle.

    You didn't read through all of my symptoms/tests. "I am able to crank the engine over if I jumper relay 36."

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    naif is offline Cadillac Owners Connoisseur
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    Re: 2002 Seville STS, won't crank, engine does not turn over

    For 2002 (at least), there's no direct connection between the key and the starter - the PCM sits in the middle. So, for some reason, the PCM is deciding to ignore the start signal from the key cylinder. The PCM ground out the START 1 relay, which triggers the starter solenoid which connects the motor across the battery. If you were really careful you could pull out START 1 and jump the normally open contact to the common contact.... not really the best idea.

    Lights off in start sounds right. However the wire from the cylinder containing the start signal splits at the cylinder into two wires and goes to the DIM and the PCM. So maybe the DIM is getting the signal but the PCM isn't...

    Edit: oops, you already jumpered the relay. Wire tracing time! The wire is yellow, on PCM connector C1 pin 6.

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    ot1
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    Re: 2002 Seville STS, won't crank, engine does not turn over

    Just talked to the dealer, the neutral safety switch is inside the tranny, bummer, since I just changed the fluid a few months back. But I really need schematics before I open the tranny and the location of connectors.

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    Submariner409's Avatar
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    Re: 2002 Seville STS, won't crank, engine does not turn over

    Quote Originally Posted by ot1 View Post
    Since since this is lead acid battery, a battery having only 12v is OK, maybe not fully charged, but neverthe less sufficient to start the vehicle, and its not dead. A dead battery would read a multiple of 2.0v per cell less than 12v. (ie 10v = one dead cell, 8 v. = 2 dead cells, and so on). The point being that battery/ground strap corrosion is not the issue for this vehicle.
    Wrong. ^^^

    As a former diesel submarine main power electrician I have a slight bit of experience in the care, feeding, and testing of lead-acid batteries. Little ones and big ones.

    On our cars, the under-seat battery ground cable connections are always suspect, and you and I would not be the first ones in this Forum to find that out.

    Schematics - www.alldatadiy.com

    Where's your neutral safety switch ?? I do not believe that it is inside the transmission unless it's integral with the IMS, but labor time on the neutral switch is only 0.7 hours...........Look at START 1 relay in the underhood fuse box.

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    Re: 2002 Seville STS, won't crank, engine does not turn over

    My current battery is end of life. Terminal voltage, resting, is about 12.1-12.0 volts (verified externally). It needs to be replaced, soon, however it still works to crank down to 10 degrees F cold soak.... probably it won't be able to do that next winter. Running voltage is 14.7v (very cold soak) to 14.2 (warm), so the alternator is fine. Dead cell is not the same as end of life, though...

    What really matters is battery voltage under crank. Get someone to crank while you put a meter on the remote battery terminals. If it doesn't drop at all -> starter isn't even trying. Sagging to less than 9.6 volts means battery end of life, extreme cold, not fully charged, shorted starter, ...

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    ot1
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    Re: 2002 Seville STS, won't crank, engine does not turn over

    Hi Naif,

    I got the partial schematic from someone, my PCM fuse is good I am suppying start relay with 12v. on the other relay terminal there is 1.2v, so that is telling me the yellow wire is not open going to the PCM which the schematic says pin 44 on the PCM connector C1. Not pin 6 on C1 which is Crank Voltage.

    ----------

    Submariner,
    You didn't read my post carefully. I AM ABLE TO START THE VEHICLE when I jumper relay 36 (Start 1). I have also installed 400 amp single cell batteries just like on your sub, only in telephone switchrooms, I too know when a battery is dead or not. There is no drop in voltage when I attemp to start the vehicle with Relay 36 in place. I do not have a significant grounding issue concerning the battery, it maybe slightly corroded but that is not the issue here. My battery was simply not charged and there was a load on it, hence the 12v, point is that the voltage didn't drop significantly while attempt to crank. So what I stated is in fact true about battery voltage and approximately 2v per cell. I could be losing .6 volts in the wiring from the back seat to the engine cmpartment. Its not critical, whether I have 12v or 12.6v during crank, the battery is not dead, and the cabling is supplying sufficient amps to start the vehicle. I will clean up the corrosion when I pull the back seat if there is any.

    I don't subscribe to AllData, people have told me its full of errors.


    Well I guess I will have to run over to the dealer to verify where the Neutral switch is located. With .7 hours repair time it can't be inside the tranny. But that is what the parts guy told me.

    ----------

    What I need is a flow chart to tell me why the PCM/ECM is not grounding Start 1 (relay 36).
    What pins of the PCM is the Neutral Safety switch connected to?

  10. #9
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    Re: 2002 Seville STS, won't crank, engine does not turn over

    I called another dealer parts guy, Neutral Saftey switch is in the tranny he says. Are you sure that picture is an 4T80E, kinda looks different from what I remember. If I could see a bottom view I would know.

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    Re: 2002 Seville STS, won't crank, engine does not turn over

    Quote Originally Posted by ot1 View Post
    I called another dealer parts guy, Neutral Saftey switch is in the tranny he says. Are you sure that picture is an 4T80E, kinda looks different from what I remember. If I could see a bottom view I would know.
    Yep - that's out of the 2002 Seville GM service manual.

    Your "battery dead" one cell at a time analogy is untrue - cells make up a "battery" and the whole assembly loses voltage uniformly unless one cell shorts internally and "dies", then the battery would show significant decreasing voltage steps. When the battery reaches 11.9 to 12 volts measured across the terminals, unloaded for a half hour, there is just not enough amperage left to provide much in the way of "power". If your battery measures higher than that, then yes, you have some other connection (amperage transfer) problem.

    I wonder if something has happened to or in the TheftLock system - these cars have a start/ignition disable when certain voltages/sensors detect a possible theft attempt. Does this car have an aftermarket sound system or remote start install, or has the dash or ignition switch been removed/replaced recently ?

    For 2002, here are the PCM pin diagrams...............you'll have to click the thumbnail and zoom in.

  12. #11
    naif is offline Cadillac Owners Connoisseur
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    Re: 2002 Seville STS, won't crank, engine does not turn over

    I think Theftlock disables injectors as well so he wouldn't be able to override by jumpering the start relay if theftlock was the problem...

    ----------

    Quote Originally Posted by ot1 View Post
    Hi Naif,

    I got the partial schematic from someone, my PCM fuse is good I am suppying start relay with 12v. on the other relay terminal there is 1.2v, so that is telling me the yellow wire is not open going to the PCM which the schematic says pin 44 on the PCM connector C1. Not pin 6 on C1 which is Crank Voltage
    Crank voltage = sense from the key cylinder. I think it may not be getting to the PCM (the PCM has to command the start relay closed, which you're working around by jumping the relay.)

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    Re: 2002 Seville STS, won't crank, engine does not turn over

    Quote Originally Posted by naif View Post
    I think Theftlock disables injectors as well so he wouldn't be able to override by jumpering the start relay if theftlock was the problem...
    Yeah, I'm looking at that now - the PCM connector pin diagrams are posted in #10.

  14. #13
    Mark C's Avatar
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    Re: 2002 Seville STS, won't crank, engine does not turn over

    Crank Request signal comes from the ignition switch thru a yellow wire to PCM connector C1 terminal 6. Should have 12V with the key in start. Wire passes thru under dash connector C200 terminal B2, and engine compartment connector C101 terminal B6.

    Starter relay coil gets power from the 10A PCM IGN Fuse (fuse 19). Power flows from that fuse to terminal 86 on the relay, thru the coil wires out terminal 85 thru the under fuse block connector C3 on terminal C3 which has a yellow wire. From there it goes to PCM connector C2 terminal 44. The PCM provides a ground to pick the relay when the crank request to the PCM is satisfied.

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    ot1
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    Re: 2002 Seville STS, won't crank, engine does not turn over

    SubMariner,
    The grounding bolt under the back seat was rusty as hell (threads), so i replaced it and used some aluminum antiseize on it. Now I have 12.44 volts in the engine compartment when the key is on. But still have the same no start condition as before. Thank you for that tip. About the battery, yes I know there are 6 cells, and yes more than one cell can go dead at a time. And I check specific gravity before and after charging if I suspect a battery is at fault. My point from the getgo was that my battery had enough voltage/amps in it to crank the starter and the dash lights (and headlights, although I didnt mention them) were nice and bright.

    Tommorrow I will look at pin 6/C1 (yellow) on the ECM and see what voltage is there?

    Ignition switch was never replaced, no aftermarket alarms, nor aftermarket radio.

    Somehow I missed the code P0615C which appears immediately after attemping to start with relay 36(Start1) in place. But the SES light doesnt come on, this code doesn't set it, so I guess thats how I missed it.

    Also in the Genisis says I get a Start signal so I bet this is telling me pin 6 goes hot.

    MarkC. fuse 19 is good. I have 1.2v on pin 85, so thats telling me its connected to the PCM but tommorrow I will buzz it from the PCM 44/C2 back the Start 1 (relay36) to be sure.


    What about pin 41/C1 Transmission Range Switch? what is suppose to be on it?

    Does anyone have the flow chart for the start circuit?

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    naif is offline Cadillac Owners Connoisseur
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    Re: 2002 Seville STS, won't crank, engine does not turn over

    DTC P0615
    Circuit Description

    The PCM supplies a ground path for the starter relay when start enable has been requested. The PCM monitors this circuit for conditions that are incorrect for the commanded state. If the PCM detects an improper circuit condition, starter relay DTC P0615 will set.
    Conditions for Running the DTC

    System voltage is between 9 and 16 volts.
    Conditions for Setting the DTC

    The PCM detects an improper voltage level on the output circuit that controls the starter relay.
    The condition exists for at least 2 seconds.

    Action Taken When the DTC Sets

    The PCM will not illuminate the Malfunction Indicator Lamp (MIL)
    The PCM will store the conditions present when the DTC set as Fail Records data only.

    Conditions for Clearing the MIL/DTC

    The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
    The DTC can be cleared by using the scan tool Clear DTC Information function.

    Diagnostic Aids

    Ignition system DTCs set with the ignition switch in the START position if the starter relay or the starter is inoperative. When the PCM enables starter operation, the PCM also initiates the diagnostic test routines for DTCs P0335, P0340, and P0385. If a condition exists which prevents the engine from cranking, the PCM will not receive signal input from the CKP and CMP sensors, and the DTCs will set.

    Reviewing the Fail Records vehicle mileage since the diagnostic test last failed may assist in diagnosing the condition. The information may help determine how often the condition that set the DTC occurs.

    --------------

    Did you try swapping the START 1 relay? Also check PCM IGN fuse and START circuit breaker.

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