91 Dodge Dynasty 3.3 cranks but dies right away.Tried everything but new ecm

Discussion in 'Domestics' started by 91dynasty, Mar 13, 2013.

  1. The old man

    The old man Hero Member

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    Maybe it is time to show a schematic. What I would do to totally eliminate the ASR from possibly shutting down by having a bad connection coming from the run contact on your ignition switch, because of excessive amp draw because of the connection, would be to run a wire directly from my positive post of my battery to the Dk Blue wire connection at the ASD relay. This would insure that you would always have a good 12 power to the relay at all times, insuring that your fuel pump, the direct ignition system, and your fuel injectors, ignition feed to the sbec , and your injector feed from you sbec would have full power through the asr relay and not intermittint. Had to do something like this a few months ago on a 92 Dodge for a friend of mine on a full size van to get it to start. Don't know if it will work, but worth a try in my humble opinion.
     

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  2. billr

    billr wrench

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    Did you but this car new? It may have an anti-theft system on it that you don't know about. For a long-shot (but easy to try) disconnect the electrical connector to the TPS. Maybe that has failed in a mode that is telling the ECM you have invoked "flood clear" and so injectors are being disabled.
     
  3. 91dynasty

    91dynasty Jr. Member

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    I have tried to replace the SBEC - same outcome. So it isn't the alarm issue. I tested the ASD relay according to alldata database. First made sure +12 comes to the relay.Checked 12 volts during cranking on terminal 87. In the run position of the switch the +12 was on terminal 86 of the relay,just as it suppose to. And on the terminal 87 the voltage was present during the cranking and 2 seconds later it was down to 0.9 volts- just as the testing procedure outlined. To make sure it is not the relay I will run +12 to the terminal of the relay just to rule out any intermittent dropouts just as The Old Man suggested and I will report back tomorrow.
    I am too stubborn to let it go now. :)
    Thank you for all who contribute.

     
  4. NickD

    NickD wrench

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    Recall working on something like this way back when, would shake our heads and say, Chrysler electronics. Tested the skills of an electronic engineer, poor connectors, ECM, BCM loaded with flux solder joints, and this thing with the voltage regulator in it.

    [​IMG]

    Was really a major job, but the car was worth something back then, whole idea was to get it running and get rid of it. Do somehow recall replacing all the injector driver transistors with something good and spending every free moment of about two weeks working on it. Started getting the idea that life is too short.

    Do you have a shop manual and a bunch of electronic test equipment?
     
  5. The old man

    The old man Hero Member

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    The friend that I was referring to that called me on the phone when his 92 Dodge van would not start, ran a 12v positive to the coil positive. He already replaced the asd relay. When I looked at the schematic on his, I seen that the coil positive and all of the other wires that ran the injectors, fuel pump etc were on the same wire as the coil positive, so that eliminated any broken or bad connection that may be in that part of the system, including connections or bad wires that may be on the bottom of that asd relay plug in your relay box. You may even want to go that way to make sure it is not in the asd relay plug or connection,(Dk gr//orange wire in my schematic). It started right up and he ran it that way the rest of time he was in Ohio and finally drove it south to Alabama to stay. He was not interested in what the root problem as I was, he was just a poor man and glad as hell it didn't cost him anything more. I told him that he had to unhook that wire when he was through driving or else it would be like keeping the ignition switch on all the time and run the battery all the time. I don't know if he listened or not. Most of my friends and family are far from Rich and mainly middle or lower class, so glad to help them out if I can.
     
  6. greasemonkey

    greasemonkey Hero Member

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    What is the number of the new sbec(engine control). If you do not have the right one it will do the same thing. Has to be for a 91 with a 3.3l with out alarm. Best to order it from the dealer with the vin number if not you are will have no idea if it is rightor not as they all look the same. The VIN will tell the dealer the right one that came in the vehicle. HTH Greasemonkey :)
     
  7. 91dynasty

    91dynasty Jr. Member

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    The computer I tried was 4686442 - the same number that Chrysler bulletin recommends to replace original with.

    I also checked the +12 volt comes from shutdown relay to ECU leg#8 (voltage reference) and also goes to ignition coil and injectors. So coil and injectors and so as computer terminal #8 are energized.


     
  8. pressman1965

    pressman1965 Jr. Member

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    I know how you feel with this problem I had to replace this ECM 8 years ago this might help
    check the date the car was Manufactured it is inside the drivers side door use this date to get the proper unit my car was Manufactured on 10 month 1990 good luck
     
  9. 91dynasty

    91dynasty Jr. Member

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    Good evening.

    According to Alldata description of ASD and schematic diagram the ground to the auto shutdown relay is coming from the SBEC (ECU) and is turned to the auto shut down relay only if signal from distributor is present when key is in the run position. I tried to check the ground with the key in "ON" position and relay removed and ground isn't coming to the auto shutdown relay from the SBEC. So at this point it is either SBEC or no signal from crank sensor. I already replaced a crank sensor so unless it's a broken wire somewhere between sensor and SBEC it points at sbec. When I connect the terminals of Auto shut down relay using a jumper wire the fuel pump comes on and problem persist i.e cranks and dies within 2 seconds. Anyone got any input?
    Thank you for helping along!

    [​IMG]
    [​IMG]
     
  10. The old man

    The old man Hero Member

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    Just curious, and don't shoot me for asking. when you put the new cankshaft position sensor in, did you leave the paper spacer on the end of the sensor on or did you take if off when you installed it. It is susposed to be left on the way I read it.
    Other than that, That is all I can offer for right now.
     
  11. Mobile Dan

    Mobile Dan wrench

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    Are you sure you don't have theft/alarm module?

    [​IMG]
     
  12. Mobile Dan

    Mobile Dan wrench

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    Not sure where the "mink" switch might be...

    SYSTEM SELF-TESTS
    A diagnostics mode is available in the system to verify operation of all monitored switches or circuits. To enter diagnostics, cycle the ignition key to the accessory position 3 times, leaving the key in this position.

    Upon entering diagnostics, the park and tail lamps will begin flashing to verify their operation. In addition, the horn will sound twice to indicate that the trunk key cylinder is in its proper position. Returning the ignition to the OFF position will stop the lamps from flashing while keeping the system in diagnostics.

    While in diagnostics mode, a horn pulse should occur at each of the following events indicating proper operation:

    1. Beginning with all doors closed, open then close each door. The horn will sound when the door ajar switch closes, and then again when the switch opens. There must be a 1 second delay between closing and opening the switch.
    2. Open, then.close the hood. The horn will sound when the hood is opened, and again when it is closed.
    3. Activate the power door locks in both the LOCK and UNLOCK directions. The horn will sound after each activation.
    4. Rotate the key in each of the door lock cylinders to the unlock position. The horn will sound as the switch closes, and again when it opens. There must be a 1 second delay between changing switch states, or the horn will not sound.
    ^ Press the LOCK button,horn will sound.
    ^ Press the UNLOCK button, horn will sound.
    ^ Press the mink button, horn will sound.

    5. Cycle the key to the ignition RUN position. A single horn pulse will indicate proper operation of the ignition input. This will also take the module out of the diagnostics mode. For any of these tests, if the switch does not remain open or closed for at least 1 second, the horn will only sound once.

    The lack of a horn pulse, during any operation, indicates a switch failure, the lack of that input to the Vehicle Theft Security System module, or a failure internal to the module. Check for continuity at the switch, if this is good, check for an open or shorted wire between the switch and alarm module. Also, check if a new engine controller has been installed recently. Vehicle Theft Security System will not function until 20 engine cranks.
     
  13. 91dynasty

    91dynasty Jr. Member

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    Yes I left the spacer intact. I am heading outside now to check the wires from crank sensor to the computer to make sure wire isn't broken somewhere in between. Then will attempt to run diagnostic that Danica described. And if it is no go then off to the junk yard I go. For another SBEC. I will report back when done. Thank you for valuable input!

    Danica, There is no anti theft module. I pulled the glove box and looked at it. I also wasn't able to put the car in to the diagnostic mode. I cycled the switch the way it was described so I assume that self-diagnostic procedure doesn't apply to my car.

     
  14. billr

    billr wrench

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    Way back you confirmed that it will continue running if you continue spraying "primer fuel" into the intake. That almost guarantees the ignition is OK and the crank sensor circuit is OK. Starting and running for only a few seconds might also be a symptom of the WUE (warm-up enrichment) being wrong. It will start and run briefly on the common EFI "priming" and "cranking" fuel pulse-widths, then continue running briefly and the ASE (after-start enrichment). But if the WUE isn't right, then it will soon die, as yours does. WUE is determined by the ECT sensor (the "choke" on an EFI system), so that circuit should be checked out as well; the sensors seem to fail frequently, but could also be the wiring. Backing up one step, though, have you checked for electrical pulsing at the injectors as the engine dies? If there are no pulses to the injectors, then WUE ain't it... back to the anti-theft or ECM.
     
  15. 91dynasty

    91dynasty Jr. Member

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    Billr,

    I checked the pulses with a/c voltage meter but that test wasn't conclusive. The first time I saw the 1.78 AC volts while engine ran and second time I haven't seen anything. My multimeter delays displaying voltage so it was 'thinking' and then motor died. I will get noid light this weekend or use LED and will test for pulses. I will report back.

    When you are saying ECT are you talking about Engine Coolant Temperature? If so I haven't tested it. I will test it . I assume the resistance should change with the temperature?

    There is another sensor that measures the temperature , the mixture temperature sensor. It's a temperature sensor that is bolted in to the intake and measures the intake air temperature. That sensor I have replaced last year because when it quit it gave me an error code.
    Just to mention, there are no error codes at the present.

    I have purchased an OTC scanner with Chrysler cartridge yesterday on ebay. It should be here mid of next week. Hopefully I will dig in the issue even deeper and be able to rule out SBEC. I went to junk yard to find a replacement SBEC but wasn't lucky. The only '91 dynasty they had sure didn't have the computer in it. Though I got a spare auto shut down relay.


     

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