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faulty ecm or not

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  • faulty ecm or not

    My Z just started stalling for no reason and will not crank back up until it cools off. Broke out the factory manual and started troubleshooting for a no start condition. Fuel pressure at 43 psi and fire at all plugs. Continued down the chart and connected a testlight to B+ and probed ckt 467 ( injector driver). Cranked engine and test light blinked bright twice, blinked dim twice, and quit blinking alltogether. Does this sound like a bad circuit board in the ecm? After engine cools off, ckt 467 blinks fine until engine gets hot again.

  • #2
    Changed out ecm tonight. Car cranks and runs now. Now I am getting a code 15. Start on this problem tomorrow.

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    • #3
      Shorted Coolant Temperature Sensor? That could blow the ECM's 5V source, and cause all sorts of trouble.

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      • #4
        IF its a code 15 that coolant temp sensor ( low temperature)
        1991 Grand Prix STE
        3.4 DOHC
        1 of 792 Produced
        Extensive Mods Done

        1991 Lumina Z34
        3.4 DOHC
        Getrag 284 5spd
        1 of 30
        Canadian Z34 Models Made with the Getrag 5spd Wahoooo!

        1980 GMC Sierra Classic C25 With 18,000 ORIGINAL MILES!!!!

        sigpic

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        • #5
          To be sure the trouble light is reading right just turn the key on and using a small piece of wire jump the "A" and "B" connector on the Diagnostic Plug and read the flashes from the CHECK ENGINE LIGHT.
          1991 Grand Prix STE
          3.4 DOHC
          1 of 792 Produced
          Extensive Mods Done

          1991 Lumina Z34
          3.4 DOHC
          Getrag 284 5spd
          1 of 30
          Canadian Z34 Models Made with the Getrag 5spd Wahoooo!

          1980 GMC Sierra Classic C25 With 18,000 ORIGINAL MILES!!!!

          sigpic

          Comment


          • #6
            Finally got a chance to check it out tonight. Found two of the pin coneectors on the computer plug were bent on the female side in the conector. Straightened the pins and car runs fine. Now waitng for the next problem.

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            • #7
              Way to go! Thats great ya got it going!!!!!!!!!
              1991 Grand Prix STE
              3.4 DOHC
              1 of 792 Produced
              Extensive Mods Done

              1991 Lumina Z34
              3.4 DOHC
              Getrag 284 5spd
              1 of 30
              Canadian Z34 Models Made with the Getrag 5spd Wahoooo!

              1980 GMC Sierra Classic C25 With 18,000 ORIGINAL MILES!!!!

              sigpic

              Comment


              • #8
                Shorted to itself no, shorted to chassis ground it can as the ECM is ground fault protected. On a chassis ground the voltage coming from that are unfiltered and may spike enough voltage to burn out the resistor in the ecm. Nine volts is enough to burn out that resistor.
                I am back

                Mechanical/Service Technican

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