Modis 6.4 software?

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  • Transman
    SDE Member
    • Oct 2006
    • 54

    Modis 6.4 software?

    I have a '95 Chevy 1 ton pickup in the shop. 6.5 turbo diesel, automatic trans. Vin# 1GBHC39F3S273687
    Problem is intermittiant stall, codes 19, 18. Crank sensor and Injector (cam) signal.
    When I go in normal Modis mode, We see engine tem at 304 degrees from cold start and never changing with temps sensor connected or not and a TDC offset at 2882.00 degrees.
    When we go in Legacy mode, we see engine temp reading accurate and a TDC at -1.9 Degrees.
    Another weird thing we see when using the lab scope portion going for ckp sensor pattern. We see the pattern @ 5.0 volts on the 4x signal dropping to 0 volts while running instead of 0 volts to 5.0 as the sample pattern shows. According to Snap-On tech both the sample pattern and the data is actual reading leading me to believe that I have something wrong with the crank sensor. Both ref volts and ground at the sensor are good. I will try to save the image from the modis and post that here also later. Transman
    We can be right or we can be wrong, But we don't learn from being right!
  • lendef
    Junior Member
    • Oct 2007
    • 2

    #2
    95 Chevy 1 Ton Diesel

    First Question. When you say temperature reads normal through Legacy? What is the reading? If it is 171 F Then it sounds like the 5 volt ref line is shorted somewhere for the ECT. The thing is it looks as if the ground for the ECT is shared by the Crankshaft sensor. Wondering if the wiring to the ect may be melted together feeding a 5 volt ref down the ground path messing up the crank sensor. I will look closer at the wiring diagram and if I can see anything more I will add. When you are getting this temperature of over 300 unplug the ect and see if 1) you have a 5 vilt ref on the yellow wire and 2 if you are reading any voltage drop between the black wire and the ground post on the battery. I will check back later. The pcm will put in substitute values when it flags a fault-in this case if the ect is reading wrong according to what I read it will substitute 171 degrees. The actual high temp would affect the timing. Hope this helps.

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