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ICV replacement drivers.

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  • ICV replacement drivers.

    I replaced one of my Idle control valve transistors in the DME.
    The Valve failed, overheated one of the PH ON588 m9026 ICV transistors, which apparently vibrated out of the circuit board.
    I will be trying an NTE Electronics NTE 196 04 2C.

    Update pending the replacement of the ICV and some of the hose under the plenum.

    I could not find a source for the original transistor.
    Fingers crossed.
    Last edited by Mmark; 02-07-2005, 07:58 AM.

  • #2
    I had the same issue a year ago, I ended up using an equivalent tranny from Radio Shack, it worked perfectly.



    • #3
      Installed the NTE Electronics part# NTE196 042C transistor in place of the loose and slight burnt factory piece.
      The other factory resistor was fine so my burn from the failed ICV was mild.
      Replaced the ICV and leaky CCV hoses.
      To recap
      1, 1100-1600 rpm oscillating idle
      2, poor drivability, both cold and hot.
      3,Inconsistent power delivery
      4, car would leap forwards when clutch pedal was depressed and you were on the brakes for a stop sign or other.
      5, The car would nose dive when the throttle pedal was released.
      6,slightly worse fuel mileage.

      500 miles After the transistor replacement along with the ICV and CCV hoses.

      Idles at 750 with the occasional burp, but rock steady.
      Issues 1-6 resolved.
      Transistor cost me 5 bucks as ordered thru a computer repair store.


      • #4
        Thanks for the update and PN.

        All this talk of failed ICV's frying the transistor has mad me decide to replace mine before anything happpens.


        • #5
          Any good place to pick up this transistor? ( website etc) I'll write the number down and try Fry's, i'm sure they would have it or it's equal, I bought some from radio shack, but not sure the right one to use, would hate to solder in a wrong transistor.

          The Chuck giveth, and the Chuck taketh away


          • #6
            I had the bloke at the computer repair store source the transistor.
            Knowing more about electronics than I do, He evidently went to the NTE electronics site(supply this stuff) and searched for their equivalent/replacement for a TIP31 transistor.

            Evidently, a failed ICV fries one or both of these transistors in literally seconds once it's impedance drops to 12 ohms from a nominal 19.6 to 20.6 ohms.
            This makes the ICV and expensive maintenance item although it is not specific to the M3. ( E30 325's use it).
            I suppose one could do a monthly impedance check by hooking a DVOM across the ICV sub harness at the area of the fuel rail, and make sure you have at least 19 Ohms between T2 and T1 and between T3 and T1.

            One thing for sure... don't loan out your DME to someone having an oscillating idle as it will fry the transistors in your DME.
            Last edited by Mmark; 02-28-2005, 09:47 AM.


            • #7
              Evidently, a failed ICV fries one or both of these transistors in literally seconds once it's impedance drops to 12 ohms from a nominal 19.6 to 20.6 ohms.

              You mean like this ?

              that's my ECU, apparently I had the same 1 transistor go bad and not both. I want to make sure I get the correct transistor before i solder it in, guess i'll ask around and mention that model you gave me

              The Chuck giveth, and the Chuck taketh away


              • #8
                Aye, that's it/them.
                On mine the RH one was fine and OE.
                The LH one had melted the plastic lock and the solder, and fell out.
                The car died mysteriously once and did not repeat the trick so maybe the loose transistor was bugging the DME circuits.


                • #9
                  Very glad you mentioned TIP31 as the transistor(s) we need to replace. If this is indeed the correct one, I got these from Radio Shack for $2 and some change, here's a few pics of them with their part number and voltage etc ranges, one final check to make sure these are the right ones, if so other members might want to buy a few as we know for sure now where to get them for cheap.

                  Everything look good here? if so, in they go, might as well replace both to be safe

                  The Chuck giveth, and the Chuck taketh away


                  • #10
                    sorry if i'm hijacking this thread, but I have a few questions about this issue

                    Around what mileage/hours does this happen? Currently my car has 50,000 miles on it.

                    Are the replacement transistors a permanent fix, or will it happen again with a faulty ICV?

                    If it's not a permanent fix, why not remove the factory ICV and replace with a aftermarket ICV 12v solenoid? Bypass the DME all together and forget about this frying non-sense.


                    • #11
                      It happens as soon as the resistance of the electronics in the ICV fail due to the environment the ICV lives in.
                      Once the resistance between the terminals gets to 12 or so ohms, the current starts to overheat the transistors in the ICV.
                      There is no way of predicting when, but with the age of these cars, mileage or not...could be anytime.
                      It is not a permanent fix, as far as transistor/bad ICV replacement goes, but.

                      I'm thinking of adding a resistor to the wire that carries +12 v voltage to the ICV. This may, or may not prevent DME damage in the event of future ICV failure.