F355 accelerometer 154310 (5.2) | FerrariChat

F355 accelerometer 154310 (5.2)

Discussion in '348/355' started by Klas, Jun 3, 2017.

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  1. Klas

    Klas Formula Junior

    Mar 17, 2014
    327
    Gothenburg, Sweden
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    Klas Nilsson
    Anyone experience problems with this unit? I got a dtc for it "no signal" and amber chassie light is on in my dashboard. Easy to exchange? Don't find a fuse either. Expected the front fuse box to have one, but no...
     
  2. Qavion

    Qavion F1 World Champ
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    The vertical acceleration sensor appears to get (some) power from the Airconditioning fuse (on the green/white wire). However, this fuse not only powers the airconditioning, it powers some of the instrumentation, too. You would notice the fuse was blown straight away.

    Sorry, no experience.
     
  3. Robbe

    Robbe Formula Junior

    Aug 22, 2013
    609
    The Netherlands
    isn't that the device behind the front bumper? There are 2 items in the middle just behind the front bumper, I believe one of those is it.
     
  4. Klas

    Klas Formula Junior

    Mar 17, 2014
    327
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    Klas Nilsson
    Yes, it's located behind the front bumper. I thought it strange that it had not an own fuse and no info on which fuse it could be connected to, but it might be the AC fuse as stated earlier in this tread. Maybe I have a cable or connector problem as the AC is working.
     
  5. Qavion

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    #5 Qavion, Jun 3, 2017
    Last edited: Jun 3, 2017
    It's possible. However, it's difficult to get to the sensor to check the wiring. Also, I don't know if that fuse powers everything in the accelerometer. It could be some kind of heater power to keep the sensor warm?

    Anyway, on the sensor:
    Pin A is AC fuse power
    Pin B is earth (ground)
    Pin C and D both go to the Suspension ECU (in front of the passenger footpad relay/fuse panel)

    Here's the diagram. Please ignore the wiring for the Anti-Theft System (I haven't completed or checked it yet).

    Suspension Diagram (5.2)

    Hope this helps
    Cheers
     
  6. Klas

    Klas Formula Junior

    Mar 17, 2014
    327
    Gothenburg, Sweden
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    Klas Nilsson
    Thanks for the wire diagram
     
  7. Klas

    Klas Formula Junior

    Mar 17, 2014
    327
    Gothenburg, Sweden
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    Klas Nilsson
    Finally after not spending too much attention to my amber light for a while, the problem seem to be solved. I swapped the accelerometer 154310 with another car, erased all dtc's and the light went out. Now I ordered a new part. Unfortunately it´s VERY expensive but I do not want to take the risk on a used part. Who knows if that its working properly or not?
     
  8. Qavion

    Qavion F1 World Champ
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    Sounds like you've made some progress, Klas.

    Are you considering buying a used sensor and checking it before fitment? (If you knew how)
     
  9. Qavion

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    Klas, would you be able to get some voltage values being sent to the accelerometer? (at the accelerometer disconnect plug)

    We know that pin "A" is receiving 12volts (dc) when the ignition is turned on (from one of the passenger footpad fuses). We know that pin "B" is earth (ground). Do you get any voltage readings (ac or dc) with pins C & D (using B as earth?)

    The Workshop Manual says that the malfunction code only tells you if the unit is connected (not that it functioning). If we can find out which pins are being checked for circuit continuity/connection, we can use this as a basic check for any replacement sensors.

    The accelerometer may be using the 12volts on pin "A" for the acceleration circuits or it may be using a smaller voltage supplied by the suspension ECU (on pins C or D). In the latter case, using a 9V battery-powered multimeter to check resistance may not be a good idea. If we can find out what voltages are being used, we can use these as test voltages.
     
  10. Qavion

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    In my impatience, I thought I'd check the voltages myself...

    I didn't remove my front fender (bumper), but I was able to check some voltages at the forward luggage compartment relay panel (one man job, rather than two).

    Using the same diagram as above:

    F355 (5.2) Bilstein Suspension Wiring Diagram

    On plug B of the relay panel (with accelerometers connected... i.e. with plug B still connected) and ignition ON, I measured:

    Pin 5 (Horizontal Accelerometer blue/red wire): 4.7vdc

    Pin 4 (Vertical Accelerometer pin "A", green/white wire): 12.3Vdc (car battery voltage with trickle charger attached via passenger footwell panel fuse 24))
    Pin 6 (Vertical Accelerometer pin "C", violet wire): 0.43Vdc
    Pin 9 (Vertical Accelerometer pin "D", grey/green wire): 0.43Vdc

    I then disconnected plug B to simulate the accelerometers being disconnected:

    Pin 5 (Horizontal Accelerometer blue/red wire): 4.7vdc (no change). Looking at the diagram, all it seems to be is a switch.

    Pin 4 (Vertical Accelerometer pin "A", green/white wire): 12.5Vdc (battery voltage with trickle charger attached) No or little change as expected.
    Pin 6 (Vertical Accelerometer pin "C", violet wire): 2.5Vdc (big change)
    Pin 9 (Vertical Accelerometer pin "D", grey/green wire): 2.5Vdc (big change)

    I didn't check to see if there were any test pulses sent to the accelerometers immediately after ignition ON.

    I was surprised to see the Suspension ECU sending voltages to three different pins on the horizontal accelerometer. I'm still not sure if the 12.3 volts on pin "A" of the accelerometer is for powering a heater circuit or if it's powering a sophisticated circuit with transistors, etc (which is contributing to the voltage change on pins C and D).

    Anyway, at least we know what voltages with which to test the accelerometer: 12.5Vdc and 2.5Vdc for the vertical sensor and 4.7Vdc for the horizontal sensor. If you see any major variations from my test results, we can probably assume the sensor is broken.
     
  11. Qavion

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  12. Qavion

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  13. Klas

    Klas Formula Junior

    Mar 17, 2014
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    I did not consider a used part so I ordered a new one. $1000.... not funny but...what the hell, problem solved.

    Btw, checked all wiring and there was no fault or bad ground or anything wrong there. The only part left was the accelerometer.
     
  14. Qavion

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    Good to hear the problem had finally been solved, Klas :)

    What will you do with the old one? I'd be curious to know what's wrong with it. The metal block may simply have been displaced, causing a short circuit as shown in the other message thread.
    (Having said that, I'm not sure if any kind of recalibration/adjustment would be required).
     
  15. Klas

    Klas Formula Junior

    Mar 17, 2014
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    Yes, that might be of some interest but my Ferrari tech. got he old one actually.
     
  16. Qavion

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    Sorry to hear that, Klas... I was even thinking of buying it from you for experimentation.

    I wonder what they mean by "permanently". I've had actuator problems before, fixed them and not had to reset the suspension computer to get rid of the light. Unfortunately, even with long term power removal and a couple of drives, I haven't been able to get rid of the light.
     
  17. Qavion

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    Update... After not being able to clear my suspension light, I went to my local Ferrari technician to have the computer interrogated and reset. He found that my right rear shock absorber actuator was faulty (broken gears). Now I'm not sure if the suspension light coming on was because I put power on the car with the accelerometers disconnected (and not going out after I reconnected them) or because I had a co-incidental actuator failure. Perhaps the light should extinguish after disconnecting and then reconnecting the accelerometers? The fault may be latched in the memory, but perhaps the light itself isn't latched on?

    Anyway, fortunately, I had a spare actuator (repaired by Captain Z a few years ago) which fixed my problem. The light went out immediately, so no computer reset required after doing this.
     

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