M2.7 F355; Errorcode 4123 (Speedometer signal) | FerrariChat
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M2.7 F355; Errorcode 4123 (Speedometer signal)

Discussion in 'Technical Q&A' started by Testa, Jul 8, 2009.

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  1. Testa

    Testa Karting

    Mar 28, 2004
    50
    #1 Testa, Jul 8, 2009
    In the right hand side motronic ECU of my M2.7 F355 the failurecode '4123' is stored which means "Speedometer signal". The speedometer itself works and also the left hand side motronic ECU has not stored this failurecode. To check if the signal is really missing at the RH ECU i need a pin/signal list of the ECU. Does anyone have such a list or a complete electrical diagramm of the car where i can identify the responsible connector pin ?
     
  2. No Doubt

    No Doubt Seven Time F1 World Champ

    May 21, 2005
    72,740
    Vegas+Alabama
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    Mr. Sideways
    #2 No Doubt, Jul 8, 2009
    I'd swap the ecus from left to right to see if they both detect a problem with the signal. The ecus should be identical.
     
  3. Llenroc

    Llenroc F1 Veteran
    Rossa Subscribed

    Jun 9, 2004
    5,495
    Colorado
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    Vern
    #3 Llenroc, Jul 8, 2009
    Last edited: Jul 8, 2009
    The speedo code is always there because the car is not moving. I assume you read the ECU for some other reason but not because your CEL was on. The signal from the speedo is only given to the LH ECU. If the speedo is working and no CEL then you have no problem that I am aware of. There is no reason to swap ECUs you WILL get the same error code on the other one.
     
  4. No Doubt

    No Doubt Seven Time F1 World Champ

    May 21, 2005
    72,740
    Vegas+Alabama
    Full Name:
    Mr. Sideways
    #4 No Doubt, Jul 8, 2009
    No. 1121 for RPM sensor just means you checked the error codes with the engine off on M2.7.

    Swap the ecus.
     
  5. Llenroc

    Llenroc F1 Veteran
    Rossa Subscribed

    Jun 9, 2004
    5,495
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    Full Name:
    Vern
    #5 Llenroc, Jul 8, 2009
    My LH ECU always shows the speedo error code. Whatever...Swap 'em around, your wastin' your time.
     
  6. Testa

    Testa Karting

    Mar 28, 2004
    50
    #6 Testa, Jul 11, 2009
    Thanks for the feedback. I know that the errorcode 1121 is always there when the engine is not running. But i was looking for the 4123 errorcode in my right hand ECU.
    The reason why i'm looking into the errorcodes is that sometimes the check engine (not the slow down !) lamp for the right hand side bank comes on but only for some seconds. This indicates a temporary failure which should be stored in the ECU. But every time i read out the ECU i get the failurecode 4123 (plus the 1121 but is don't care if the engine is not running).
    The situation for check engine light on is mostly identical: Car is slowing down with gear in, rpm above idle but throttle at idle (or only slightly touched), typical situation of slowing down in a town. I would expect that the fuel is fully cut for both banks until engine reaches idle rpm. If this situation is some seconds long without touching the throttle then sometimes (not very often) the CEL comes on. Only the two failurecodes shown above are stored afterwards. My gues was that there is a problem with the throttle sensors (eg. one sensor is telling the ECU that idle situation is there but second sensor is still above the idle threshold). But no such failurecode is stored.
    Connector to the position sensors look good, no corosion or missing contact force.
    What i can also hear with the throttle slightly touched during driving is that one bank seems to be already at idle while the second bank is cut. Only with throttle not touched at all both banks come back on to idle. Normal driving above idle is no problem, both banks on so no problem with the slow down modules.
    Seems like i have to build some adaptation to measure the throttle position signal during engine on / driving .....
     

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