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348GTB TPS reference power

Discussion in 'Technical Q&A' started by gidge348, Apr 18, 2009.

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  1. eric355

    eric355 Formula 3
    BANNED Silver Subscribed

    Nov 30, 2005
    1,223
    Toulouse (France)
    Full Name:
    Eric DECOUX
    #26 eric355, Apr 25, 2009
    Last edited: Apr 25, 2009
    This is correct. The phase sensor is a Hall effect sensor, with a so called "open collector" output. It is powered by the ECU with +5V, and its output is polarized by the ECU with a +5V THROUGH a resistor (usually a few kohms). What the sensor does is grounding ou leaving this wire open according to the index on the camshaft. The ECU reads either +5V or almost 0V. When you measure the voltage on these 2 pins with a high impedance voltmeter (digital or even analog) you should read +5V on both pins. If you install a, let's say 1 kohm resistor, on the pins you will read +5V on the power supply and much less on the sensor output pin. The exact voltage value depends on the internal polarisation resistor.
    That's great you measure +5V on both pins but it does not indicate that these 2 wires have not been crossed someday near the phase sensor. This little "resistor test" would allow you to discriminate the wires and check that they are not shorted together. Other solution is to perform a continuity AND insulation checks from the ECU connector.
     
  2. gidge348

    gidge348 Formula Junior

    Dec 12, 2008
    343
    Perth West Australia
    Full Name:
    Ian Wood
    #27 gidge348, Apr 25, 2009
    Got it.... :)


    Fan Bl**dy Tastic……………. I love this forum.....

    Pulled the phase sensor off and all looked ok, but I did notice a small mark on the cable between the sensor and the plug….. nothing major, but suspicious.

    Cut the outer insulation off and sure enough all three wires had been crushed.

    Looks like at some stage the wire had been caught in the clamp that holds the plug to side of the sensor. The outer insulation was a rubber type so puffed back up after and no one was the wiser.

    I just cut the bad sections of wire soldered together and put a heat shrink over the individual wires and tape over the outside of the 3, beautiful smooth idle pulls strong and smooth from 1000 to 6000rpm in third no splutters no misses all great.

    I am still going to take it down to put it on the oscilloscope, gas analyser, fuel pressure etc., just to be sure all is operating as expected and to give base figures for any future problems….

    Thanks again Dave, Paul, Windsock, Rick, Eric and everyone else out there, if you are ever in Perth I owe you a beer…..
     
  3. davehelms

    davehelms F1 Rookie

    Jan 3, 2004
    4,629
    Full Name:
    Dave Helms
    #28 davehelms, Apr 26, 2009
    Simple, nothing to it.....ARGH!!! Well done!
     
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