Suspension - ECU connections, fault diagnosis

Hi folks,

Hoping to get some pointers on my F355 suspension 1996/5.2. First some background, since I acquired this vehicle I've not seen any lights nor felt any change whether in Sports/Comfort, also the switch did not turn the actuators, nor did I see the amber suspension light at ignition. Time to diagnose and fix.

Yes, you guessed it. Somebody has previously disconnected the suspension ECU connectors. I can only assume a prior problem so inspected the board and cleaned all connectors. Of note, I found a copper wire resting on the board that looks to be original and may have bridged something - who knows.

Re-connected, now I have the amber light on at ignition and the suspension/shock light goes on and off with the switch. Ok, some progress. But, unfortunately no operation of the actuator (at least my test one, rear right). I did not road test at this point.

Some questions before I get deeper in to this.

Is that 3 pin blue connector bottom right to be connected somewhere? What about the Yellow/Red 3 pin connector bottom left side? I'm not seeing any receivers but perhaps these are tucked behind the fuse box and I need to dismantle. Your thoughts on next steps appreciated?

Thanks, Colin.
Image Unavailable, Please Login
Image Unavailable, Please Login

 

Took it for a short test drive. No change, suspension light did not extinguish until ignition turned off.

 

Check all 4 shock actuators and shock gears. They remove easy with a clip. If one is broken, you can get them from capt Z online.

 

Just test receptacles. Not meant to be attached.

 

One will be for the airbag and the other will be for the Bilstein unit.

The diagrams show brown/black, Grey/Yellow and Brown/Green wires for the suspension diagnostic plug. There may be two or three wires attached to the airbag plug, depends on the country/region.

 

Thank you both. Ok, I'll ignore the additional 3 pin connectors, although they may be useful for diagnosis later. I did go ahead and remove all the actuators and found the passenger front had the notorious broken gear, so just spinning with no stops. Will order a new one from Daniel at Ricambi. So started the engine, cycled the sport/comfort and no movement at all on any of the actuators. Now wondering if I have a bad ECU? Any easy way to check it? All other thoughts welcome.
Image Unavailable, Please Login

 

Did you check the sport/comfort actuator switch? Change it out with one of the others (door lock/unlock switch), and retest it.

 

Phil, I'll try that but the switch does already operate the light in the dashboard. Also, regardless of the switch, I understood the actuators would cycle during engine start which does not happen in my case.

 

Yeah, I realized after I replied that you said the dash light was working. If everything else gets ruled out, and you're down to the ECU, maybe give these guys a call to see if they can repair it:

Ferrari 355 360 430 Climate Control Programmer Computer Repair Service | eBay

 

Are you seeing the actuators spin when you simply turn on the ignition? They go through a test cycle to determine the endstops. Of course, you'll need an observer or someone to turn the key on and off.

When you were testing the soft/hard switch, did you have all the actuators removed from the shocks when you first turned on the ignition? Perhaps if the ECU can't determine the endstops initially, it won't even bother trying to switch between soft and hard.

Did you notice any fuses inside the suspension unit? The main power for the unit seems to come directly from the battery with no fuses, so the unit must be protected with something. Battery power goes into the unit on plug A's pin 11 (red wire).
Note that there is additional power going to the unit from the AC System Fuse, but neither suspension light would illuminate if this was blown.

It's probably a good time to find someone who can interrogate the unit. It might pinpoint if the problem is internal or external.

Good luck!
Cheers

 

Ian,

There is no movement from the actuators when the ignition or engine is turned on. I did not investigate the power side of things because I witnessed the dash lights coming on so assumed power was good, perhaps I'll check in to that a bit more with a meter.

I think the actuators on my 550 Maranello may be the same and I could pull one of those (known to be good) and test. Pretty sure the ECU is different though.

Thanks, C.

 

Colin, if you do decide to check the wiring, here's the diagram for the suspension.

5.2 Suspension diagram

Looking at all those wires, it could take days to properly check all the external wiring for power, open circuits and shorts. Maybe start out with just the power? If you can't see any internal fuses, maybe that copper wire resting on the board acted as a fuse. Can you trace that to any of the connector pins?