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550 resurrection issue. Gurus needed

Discussion in 'Technical Q&A' started by leavingofage, Aug 29, 2023.

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  1. leavingofage

    leavingofage Rookie

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    #26 leavingofage, Aug 30, 2023
    Oh I missed one post… Qavion, both iac connectors are light grey
     
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  2. tazandjan

    tazandjan Three Time F1 World Champ
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    #27 tazandjan, Aug 30, 2023
    You should move this thread to the 456/Maranello forum.
     
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  3. Qavion

    Qavion F1 World Champ
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    #28 Qavion, Aug 31, 2023
    Thanks. Unfortunately I couldn't figure it out from that. Both sides appear to have 2 grey connectors.

    Left hand harness here:

    Image Unavailable, Please Login

    The wire marked with the blue dots seems exceptionally long and might be the IAT, but it has branches I don't understand.

    Anyway, the wiring diagram shows the IAT hooked up to the Left ECU. A continuity check could be done on the pins if required.
     
  4. Island Guy

    Island Guy Karting

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    #29 Island Guy, Aug 31, 2023
    Only one harness will have a connector for the IAT. The extra long section of the harness is for the EVAP valves which are rubber-mounted to the front of each air box. From the factory, the "excess" wiring is tied up with a tie wrap.
     
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  5. Qavion

    Qavion F1 World Champ
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    #30 Qavion, Aug 31, 2023
    Agreed. I’m just trying to figure out if the WSM graphic posted earlier is showing the (hard) wiring connections. e.g Is the right hand side TPS (dual plug type) directly wired to the left or the right ECU.

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    The original WSM wiring diagrams show the dual plug TPS harwired to the Right ECU. Is this an error or is the data sent from the R ECU to the L ECU via the CAN Bus?
     
  6. leavingofage

    leavingofage Rookie

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    #31 leavingofage, Sep 2, 2023
    when I get back home Monday I will dig in and give you the answer!!!

    well… maybe Tuesday.. have to finish a pita head gasket job before I get back to the 550
     
  7. leavingofage

    leavingofage Rookie

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    #32 leavingofage, Sep 20, 2023
    Hey guys…. Sorry life got in the way of Ferrari time lol.

    @Qavion I believe that to be the case but I’ll check.

    I’ve been doing some digging today. I am starting with the communication code… and got some interesting results.

    when I test the wires at the ecu connectors, both disconnected from the ecus, Pins 85 and 86 (can comm + and -) have 60 ohms resistance between them. However the resistor between the two sides is 120 ohms (connector 152). With the resistor removed, there is 120 ohms between 85 and 86. The resistor itself ohms out at 120 as it should.

    Also with the resistor removed, both 86 pins have continuity to one side of the resistor, but do not have continuity between them.

    Pin 2 of the LH dashboard connector (179) is the CAN + wire. But there is no termination point in the diagram. Pin 2 on the RH dashboard connector (277) operates the CEL directly from the RH ecu.
     
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  8. Qavion

    Qavion F1 World Champ
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    #33 Qavion, Sep 20, 2023
    Last edited: Sep 20, 2023
    The termination point is shown in the ABS /ASR Wiring Diagram:

    https://www.dropbox.com/t/ttpLqzNnz5adHAzn

    Link expires in 6 days.

    Note the second resistance in component 184 on the left side of the diagram.... although I'm not 100% sure of the pinout on the 3 pin plug.

    The second resistor is on the left hand side of the engine bay near the Power Steering Reservoir.

    You're probably measuring two 120 ohm resistors in parallel (= 60 ohms).

    Treat any Left or Right labelling in my 550 wiring diagrams with caution until we figure out how the engine components are wired up (in reality).
     
  9. Qavion

    Qavion F1 World Champ
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    #34 Qavion, Sep 20, 2023
    Last edited: Sep 20, 2023
    This is odd... The second resistor is shown as an inline connector in the wiring diagram graphics

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    Would it be possible for you to take a photo of it?

    Plug 175 next to it is the ABS/ASR module.

    Note that I'm relying on hearsay regarding this resistor. The description of 184 in the WSM is "Connecting joint between ABS/jumper or electric actuators".... whatever that is.
     
  10. leavingofage

    leavingofage Rookie

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    #35 leavingofage, Sep 21, 2023
    Oh… so the resistor that I found was 184… NOT 152. So I can confirm that resistor is 120ohms as well. Mine has yellow, Black and a shield wire… which is black also. In the pics it bolts to that hole behind it… just removed it for testing. Note that is how it was… just with clear heat shrink over the resistor.

    So where the hell is 152?

    I honestly didn’t even look at the abs/asr diagram. That makes sense that there’s 2 120 ohm resistors in the loop.

    And yeah I want to confirm as much as I can while I have this car.
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  11. Qavion

    Qavion F1 World Champ
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    #36 Qavion, Sep 21, 2023
    Last edited: Sep 21, 2023
    Good question. The closest number I could find was 151 and that was in the driver's footwell (perhaps behind the kick panel ... door side). I thought I had pictures of that area, but I can't find them. I have photos of the left and right ECU harnesses and none show a similar plug near the ECUs. Perhaps it's like the F355. The resistor is actually inside the backshell of the ECU connector.
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    I've labelled it the "F1 resistor" because that's the only thing the F355 Motronics ECU talks to on a CAN Bus. I don't expect you to pull your plug to bits to find it, though. I'm not even sure which ECU it's attached to.

    Thanks for the pics. That confirms that the resistor is across the yellow and middle black wires. Anyway, your resistance measurements seem to check out normally: 60 ohms for the resistors in parallel.
     
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