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Northstar Engines and System Technical Discussion Discussion, P056 in Cadillac Engine Discussion; Hello all, I have a code that is really starting to annoy me. The code is a P056 which is ...
  1. #1
    51magnum is offline Cadillac Owners Member
    Join Date
    Jul 2003
    Boise, ID


    Hello all,
    I have a code that is really starting to annoy me. The code is a P056 which is the dreaded Transaxle Input Speed Sensor. However, I am not convinced that it is not just noise on the circuit.

    Here is the symptom; it is intermittent to a certain extent:

    When I first start the car and drive out of my garage I will get a "current P056". If I accelerate rather hard for a couple of starts it will usually go away. But if I just take it easy it will remain for a few miles and then will go away. However, it will then set a "current P039" condition. Of course this will stay on until I shut the car off or clear the codes while driving. If I do not clear the codes and drive to work (20miles) I get bad gas mileage. I know this is because the torque converter is "not locking" up.

    So experts what can I do? I have just moved the spark plug wires but they were still in the original looms and about 2in from the wire harness.

    Please help!

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  3. #2
    51magnum is offline Cadillac Owners Member
    Join Date
    Jul 2003
    Boise, ID
    Thread Starter

    Re: P056


    The on-board diagnostics are incredible.

    Ok, here is more on the symptoms:
    I drove out of the garage this morning but this time I was looking at PD72 (Input Speed Sensor Data) and it was indeed 0. Not 10 or 20 but flat 0. It says if it is below 100 then it might be a short or open. So while driving to work I continued to look at PD72 and I could get a response when I would accelerate hard. It would indicate 2500 or so but then immediately drop back to 0 after I let up on the gas. So I kept watching it and as I entered the freeway it started to rise from 0, i.e. it jumped to 500 then back to 0 then up to 2300 then to zero and then it finally stabilized at around 2300 or so.

    What do you guys think? Must be a short or open or something; I am thinking it has to do with heat? Maybe oil/dirt in one of the connectors?

    Where is the sensor located? I know it is DEEP in the transaxle but I mean the connector?

    Thanks in advance.

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