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Help! Throttle Positions Sensor

Discussion in 'Technical Chat' started by Dsr5drvr, Apr 27, 2012.

  1. Apr 27, 2012 at 6:46 PM
    #1
    Dsr5drvr

    Dsr5drvr [OP] Member

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    David
    Virginia
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    AMP research bed extender, Husky front liners, covercraft seat covers, wheel skinz cover.
    So my truck is throwing codes for a bad throttle positions sensor(TPS). I've hooked up many computers from multiple auto part stores. All have given me the same code. I am getting all of the symptoms of a bad TPS and I am on my second new TPS sensor since the problem started occuring. Symptoms have been: rough idle, stuttering, delayed shifting, stalling while at idle and at speed. Could it be the wiring going into my TPS connector? Or do I need a computer replacement? I havent tried adjusting the throttle cable but will be doing that first thing in the morning. Anybody have any suggestions?
     
  2. Apr 27, 2012 at 7:57 PM
    #2
    Ga tacoguy

    Ga tacoguy Well-Known Member

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  3. Apr 27, 2012 at 10:15 PM
    #3
    Dsr5drvr

    Dsr5drvr [OP] Member

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    AMP research bed extender, Husky front liners, covercraft seat covers, wheel skinz cover.
    I will get the code and post it I cant recall the exact one. It is only throwing the one code. I have cleaned my throttle body and it didnt seem to solve the issue. Im hoping it has nothing to do with any transmission problems like a bad torque converter. But while driving it seems more like a electrical issue it drives fine until it gets warmed up. Highway speeds it drives normally its not until Im driving around town and stopping at intersections when it really starts to act up.
     
  4. Apr 27, 2012 at 10:46 PM
    #4
    Dsr5drvr

    Dsr5drvr [OP] Member

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    David
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    TRD SR5
    AMP research bed extender, Husky front liners, covercraft seat covers, wheel skinz cover.
    Thanks for the replies and GA tacoguy that link to ttora was very helpful. I think that may help me and uncle my mechanic solve this issue. Hopefully I wont need an entire throttle body assemby thats pricier than the torque converter, which I am convinced is not the issue after reading the ttora post.
     
  5. Apr 27, 2012 at 11:22 PM
    #5
    Dsr5drvr

    Dsr5drvr [OP] Member

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    Vehicle:
    TRD SR5
    AMP research bed extender, Husky front liners, covercraft seat covers, wheel skinz cover.
    I had the code written down. P0120 TPS Pedal Position Sensor A Circuit Malfunction. Maybe this will help anybodies response
     
  6. Apr 28, 2012 at 4:59 AM
    #6
    Ga tacoguy

    Ga tacoguy Well-Known Member

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    Extended cab Base model 4 cyl
    Tailgate mod, horn mod,storage door mod
    :) David, according to my book, you will need to perform some checks with a high impedance digital volt meter. There should be three wires going to the TPS, and you are going to back probe these wires with your meter for their readings.The three wire are a 5 volt power and a ground and a signal wire to the PCM or computer. You are going to check for voltage going to the switch, that the switch has a good ground and that the switch is putting out a good signal to the computer.

    With the key on, but the engine off, there should be 4.5 to 5.0 volts across the reference voltage and ground wires by back probing the reference wire and the ground at the same time. If the voltage is less than 4.5 volts, check the wires between the TPS sensor and the PCM or computer for problems. If the voltage is more than 5.0 volts, check the reference voltage wire for a short to power. If the wiring and the connections are OK, but the reference wire voltage is out of range, the PCM or computer may be at fault and may need to go the dealer or a shop that can scan the PCM for problems.
    The signal return wire, the 3rd wire's voltage should vary with changes in the throttle position. Typically, according to my book, the voltage at that wire should vary from 0.5 at wide open throttle to 4.0 to 5.0 at rest or closed throttle. NOTE : this could be backward, with the throttle reading 5.0 at wide open position and 0.5 at closed position, but the transition of the throttle should show a smooth and even change in numbers.

    If the reference voltage is good, and the ground is good, but the signal return voltage is out of range or doesn't change smoothly, the TPS sensor is probably bad. I know this seems like a lot of work, but if your uncle is going to help and knows a good bit, this should not take long to check.
    Good Luck.
     
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