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355 Suspension control module

Discussion in '348/355' started by MackenzieF355GTS, Aug 17, 2019.

  1. MackenzieF355GTS

    Apr 15, 2019
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    Mackenzie Nowak
    Help! I've been working on an 1998 F355 GTS for some time now. The suspension warning light is on. I tested every suspension actuator and they all work.
    I think it may be the actual Bilstein suspension control module that may be bad. But I've also found a harness connected to the control module it has been capped off and cannot find another harness to connect.
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  2. Qavion

    Qavion F1 Rookie

    Feb 20, 2015
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    Ian Riddell
    Every computer on the F355 has a test port/plug, including the Bilstein suspension Unit. That's what you're holding in your hand. If you're absolutely sure you've tested and inspected the actuators properly, and you don't have a spare actuator and there are no other warning lights on your car, then there is not much else you can do than take your car to a Ferrari dealer or independent with an SD-1 Tool which plugs into this test port.

    I assume you've inspected the visible internals of the actuators? Sometimes the teeth are there, but the wheel itself or the supporting frame has cracked

    http://www.captainzcnc.com/id3.html

    There are a few other things which can go wrong with the system other than the actuators and the Bilstein Unit, but usually you won't be able to tell what is wrong unless you take your car to be tested.

    Welcome to the forum :)
     
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  3. Qavion

    Qavion F1 Rookie

    Feb 20, 2015
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    Here's the wiring diagram for your 5.2 car:

    F355 5.2 Bilstein Suspension System Wiring Diagram

    Accelerometer problems are rare, and you'd probably be wasting your time, but you could check to see what resistances the accelerometers are giving you (with power off the car).

    Horizontal Accelerometer: Bilstein Unit yellow plug pin 9 (blue/red wire) to earth should be open circuit (i.e. car side of the plug, not the Suspension Unit side).
    Vertical Accelerometer: Sorry, unknown. Someone checked the values on this, but later found his accelerometer was broken ($1000 for new unit). There is a metal block inside the unit which sometimes gets displaced and shorts out the electronics, but this usually results in a blown fuse. i.e. fuse 24 - Instruments, which takes out most of the instruments and HVAC system.
     
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  4. Qavion

    Qavion F1 Rookie

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    Customer's car?
     
  5. Shurik355

    Shurik355 Karting

    May 19, 2013
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    Alex Velet
    Actually my suspension light is on as well :rolleyes: looks like it's stuck in the normal mode and won't switch to the sport. The Ferrari technician from the previous owner said, "it's normal for the light to come on if the car is not driven for a long period of time", well i've been driving my car and the light haven't disappeared since.

    Im planning to get this fixed but that's down the road.
     
  6. Qavion

    Qavion F1 Rookie

    Feb 20, 2015
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    Can't say I've heard that before. It's said that starting up the car and not moving it a few times triggers the light. How long is "long"?

    Not sure of the logic behind the USA "SPORT" light. Perhaps it needs the ECU to confirm that all four actuators are in the right position before it illuminates the light. My Australian car has different logic. It doesn't have a "SPORT" light, but a light which illuminates when sport is off. That may be when any of the actuators are not in sport mode. On the other hand, it may simply be tied to the switch position.

    Anyway, do the basics.... look for broken cogs, a blown lightbulb, swap out the switch with, say, the window heat switch, then start worrying about the expensive stuff (ECU, etc).

    The other gentleman sounds like he's never worked on a Ferrari before and is hopefully handing back the car to his customer at no charge. A Ferrari independent probably would have plugged a Ferrari SD-1 tool into the ECU and diagnosed the problem in 2 minutes for free.
     
  7. Qavion

    Qavion F1 Rookie

    Feb 20, 2015
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    (EDIT) On first look at the wiring diagrams, I saw a direct line from the switch to the light, but then I realised the light needed an earth. This seems to be provided by the ECU (so not as simple as I first thought).
     
  8. Shurik355

    Shurik355 Karting

    May 19, 2013
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    Alex Velet
    Our USA cars don't have sport light that says "SPORT" it just have a suspension icon on the dash that lights up once the sport mode is on. Don't you guys have the same? I know every 355 comes with sport mode, but is the light on the dash the same?
     
  9. Qavion

    Qavion F1 Rookie

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    #9 Qavion, Aug 18, 2019
    Last edited: Aug 18, 2019
    Looks like the manual is lying to me again. Or did the USA 5.2 or F1 cars have a non-ambiguous "SPORT" light.

    We have a suspension light, but it operates in the opposite sense to the USA one. In sport mode, we have a "dark cockpit" (all lights out). We don't like to have distractions when we're racing ;)
     
  10. Shurik355

    Shurik355 Karting

    May 19, 2013
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    Yeah i think the F1 have the "sport" that lights up perhaps? For the USA cars, the sport switch stiffens up the suspension. I think all the 355 are like this Ian. It wouldn't make sense not to in other non US cars. About the lights out im not sure :eek: I would still like to see where Im going :D
     
  11. Qavion

    Qavion F1 Rookie

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    Understood, but when the rest of the world toggles the switch down, the car goes from normal stiff sport mode to comfort mode.

    For me, the safest mode is the "normal" mode.
     
  12. 308 GTB

    308 GTB F1 Veteran
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    #12 308 GTB, Aug 18, 2019
    Last edited: Aug 18, 2019
    Ian,

    My US 1995 F355 Challenge (Motronic 2.7) also defaults to SPORT MODE. The suspension mode switch on the main console is used to turn on the COMFORT MODE and the amber shock absorber light on the instrument panel illuminates (#2).

    My car has 2200 lb/in front and 900 lb/in rear Challenge springs and I leave the suspension mode switch in the SPORT position.

    Barry


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  13. Qavion

    Qavion F1 Rookie

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    Curioser and curiouser. Seems there are a few variations. I can see where I got confused. In the manual's chapter "Controls F355 97 & 355 F1") there are graphics which show a SPORT light, but having said that, in that chapter, there doesn't appear to be a '97 subsection, just F1.

    For the moment, we have:
    Gated USA (probably Canada too) cars have a sport "suspension" light.
    Rest of world gated and Challenge 95's (and probably later Challenges) have a comfort "suspension" light.
    F1's have a SPORT light.

    In guess in all cases, the light comes on when you pull down on the switch (?)

    Dave L. has just reminded me that if you start the car three times and don't move the car, the suspension warning light comes on... until you move the car... but just to prove him wrong :p , I did the same and ...no suspension light. Perhaps it depends on which way the wind is blowing.
     
  14. ferraridriver

    ferraridriver F1 Rookie
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    On my 99 355 F1 the suspension light came on the fourth time the ign was turned on without moving the car. It went out with just a few yards of movement
     
  15. Steve355F1

    Steve355F1 F1 Veteran
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    Correct, Ian. My ‘98 F1 has a “Sport” light that lights up when the sport mode in ON.
    You pull the switch down to activate it.

    It also triggers the suspension light after three starts without moving as Dave has just said above.
     
  16. Qavion

    Qavion F1 Rookie

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    Could it be an F1 thing? The other Dave has an F1, too.
     
  17. Qavion

    Qavion F1 Rookie

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    Ditto with Steve.

    The F1 SPORT switch has an input to both the Bilstein ECU and the F1 TCU, but I'm not sure if the two ECUs talk to each other on the CAN busses. The Bilstein Unit has the same part number for gated and F1 cars. The Bilstein unit puts on the suspension fault light, so if there are any variations in the 3 starts (or ignition ON) logic, there has to be something talking to the Bilstein ECU to put on the light.
     
  18. 308 GTB

    308 GTB F1 Veteran
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    Ian, my USA 1995 F355 Challenge was ordered as a stock 1995 F355 Berlinetta and converted to a Challenge car by Miller Motorcars. That's how the early North American F355 Challenge cars were made in 1995.. When Motronic 5.2 was introduced on the 1996 F355s, the Ferrari Factory retrofitted the Motronic 2.7 ECUs and plumbing to keep the F355 Challenge cars homologized.

    There is also a Suspension Malfunction Warning Light (#19) on the instrument panel which illuminates for about three seconds when the ignition is switched on and then goes off. If there is an electrical malfunction in the suspension system while the car is moving, the ECU lights the Suspension Malfunction Warning Light and sets the shock absorbers to a fixed safety setting.

    Barry
     
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  19. Qavion

    Qavion F1 Rookie

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    Barry, does your USA manual car have the logic which locks on the fault light after 3 starts (and no car movement)? (or 3 x ignition key to ON and no movement)?
     
  20. 308 GTB

    308 GTB F1 Veteran
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    No, Ian. My 1995 Motronic 2.7 car doesn't have that logic. As a race car, the ignition is often switched on and off without starting the car to check fuel, running lights, etc. During refueling, the battery cut-off switch is used. Warming up the car allows the ECU to relearn its parameters.

    My car has a shielded master ignition switch...


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    The two toggle switches allow me to override the system and manually turn on the left and right cooling fans. The keyed ignition switch serves only to start the engine.
     
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  21. 308 GTB

    308 GTB F1 Veteran
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    Yes indeed, Ian. My 1995 F355 Challenge is just as it raced during the North American Ferrari Challenge Series in 1995 and 1996. The only change I made was to have the car conservatively tuned by adjusting the air/fuel mixture with pulls on a Dynojet in 2013.

    My car still has its Challenge shock absorbers and 2200 lb/in front and 900 lb/in rear Challenge springs. I've always tracked my car with the suspension mode switch in the forward SPORT mode position with the amber light (#2) off. Sebring International Raceway's track surface is very rough between Turns 17 and 2 and my car gets tossed around significantly. Most professional drivers will go to softer springs at Sebring but as it's just an HPDE event for me, I don't make any changes in my car's suspension. However, I'm curious to see how my car does in COMFORT mode the next time I'm there.

    Perhaps this experience I had might help settle the confusion. Five years ago while at New Jersey Motorsports Park, my amber suspension light (#2) suddenly came on while I was on the track. After pitting in we noticed that the actuator on the left rear shock absorber had popped off. My technicians put it back on and wired it into position as we couldn't find the C-ring. As this wasn't an electrical malfunction, the Suspension Malfunction Warning Light (#19) on the instrument panel never illuminated. The disconnected actuator put the left rear shock absorber into its default fixed safety setting which I presume is COMFORT mode and lit up the amber suspension light.
     
  22. Qavion

    Qavion F1 Rookie

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    Looking at those FChat links, we have a disagreement from another Challenge driver. Apart from that, the general consensus seems to be that up until late '98 on gated cars, the light on means soft. Did the light change to "S" on gated late 98~99 cars (with reversed default position)? On F1 cars, there is no ambiguity.

    Did seeing the Comfort light make you check the actuators? If the actuator is not fitted, the wheel on the shock strut just stays where it is (no spring-loading), so no "mechanical" default position. At least this is how it seems to be with the car stationary. Also, the motor on the actuator still works and the feedback system (as I understand it) in the actuator still works, so the system should still think everything is ok... unless it's detecting the absence of strut wheel endstops during driving (as it does during startup). However, looking at the graph of actuator position vs speed, the endstops don't seem to be reached during driving.

    The book says if there is a failure to control an actuator, the (remaining operating I assume) actuators default to the safety position (but fails to specify if this is soft, hard or intermediate). "Comfort" doesn't sound like a safety setting (unless it's taking into account poor traction situations).
     
  23. 308 GTB

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    Ian, when the Comfort light came on, I first checked to see that I hadn't accidentally moved the switch on the console to the down position. When I pitted in, I immediately checked the rear actuators and found the left one detached. When we reattached the actuator and secured it with wire, the warning light stayed off in the SPORT position and came on in the COMFORT position as per routine. I'm just reporting what happened in my car when an actuator came loose. Evidently the #2 light functions as a mechanical fault light if an actuator comes loose or doesn't work properly.


    I think that sums it up well.
     
  24. Qavion

    Qavion F1 Rookie

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    ... or perhaps a "disagreement" light between switch setting and whatever position the system thinks the loose actuator is in. I just can't see how the system detects a loose actuator when the car is in motion. The actuator position feedback circuit seems to be be contained wholly within the actuator and the commands to the actuator shouldn't reach the limits.
     

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