355 Convertible Top Control Module Repair

https://www.ferrarichat.com/forum/threads/fear-not-the-seat-pot-potentiometer-how-to-rebuild-one-without-removing-it.288373/

 

Perhaps you mean the roof emergency bypass switches. These bypass the Roof ECU (and it's logic), allowing you to close the roof even if the seats are in the wrong position or other roof sensors have failed). The handbrake must still be on.

 

Yikes... You have some serious roof issues. Sounds like one or more of your pistons is leaking. Big $$$. If you watch the video I provided a link to, the specialist recommends not topping up the fluid if it's that low. Does the car reek of hydraulic fluid? There are four pistons. Two big, two little.

 

I think I would still remove all the leather covers on the pistons and check for leaks before attempting a refill. Leaks have also been noted in the pipes which run across the firewall. More leather removal required.

 

So with that diagnostic avenue closed, we are back to changing Roof ECU relays...

If you have a boroscope /smartphone snake cam.... I guess you could check that the seat potentiometers are at least plugged in.

(EDIT) You can do wiring checks at the ECU connectors to see what the potentiometer values are like on both seats.

Roof electrical diagram here:

https://www.dropbox.com/t/kgi7SKxkhTDQeDZx

Link expires in 6 days.

 

Just trying to establish that the potentiometers are NOT influencing the manual movement of the seat. I suppose I could disconnect one of the potentiometer plugs on my seats to see if the seat still operates manually.

 

Ok.. the seat potentiometers do not affect the manual control of the seats (at least not with the seats in the mid range, I didn't try it at the endstops). I pulled the white potentiometer plug at the front of the driver's seat. No boroscope required, just good lighting.

 

I reckon your seat potentiometers are the issue and need repairing (gear gone/broken inside) and they are out of sync to where the module thinks they should be in relation to the roof cycle. Just had both of mine replaced. Drivers would only go forward so far and at one point only backwards and got stuck. Your fluid is clearly way too low and desperately needs a top and probably bleed amy air in the system. I think my garage said there is a rebuild px with your old component (note surcharge) via Maranello Classic Parts (UK). https://www.ferrariparts.co.uk/part/ferrari/64978300?id=10227

This video is also very helpful:

 

I just proved on my own car that this is not true for manual seat operation. The OP has an issue with manual seat control.

 

Yep.... Just remember where all the pieces go.

As a test, could you pull the white plug on the front of the driver's seat to see if the seat still doesn't operate with the seat switches. You just have to lift one plastic release clip to get the plug off. I've tried every which way to get the seats to stop working.

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It's just to prove that the potentiometer has no influence on your seat when using manual controls.

I've just positioned the seat at the fore/aft endstops to move the potentiometer to the limits, then disconnected the potentiometer. Either way, the seat continued to move normally.

 

Just realised a flaw in my logic. Whenever I disconnect the pot connector, it will always produce an open circuit (very high resistance), no matter the seat position, which, according to the wiring diagram, would simulate a greater than fully aft seat position.

 

Interesting. Ignore the orange wire harness. That's a seat interlock which will stop the roof operating if the seats are not in the car (i.e. the orange wire plug is disconnected). Can you see any plugs with the same wire colours as mine? Grey/yellow (2 off), black (2 off), grey/blue.

My car is a RHD, so I don't know if the seats are the same.

 

Can you figure out where the grey/yellow wire goes? Does it go to a plug with 3 pins?

The blue/black and white/black wires should be the seat motor wires. Unless that blue (with black stripe) wire is actually black (with blue stripe)

I don't recognise that 4 pin plug. Potentiometers should have a 3 pin plug.

 

Weird. Apart from the orange wires, can you see how many wires there in the driver's seat harness? I have 8 wires (plus 2 orange) on the driver's seat.

Assuming the pot has no influence on manual seat operation, only the motor wires would affect seat operation. i.e. blue (black stripe) and white (black stripe) on the driver's side (on my car at least). Solid white and solid blue on the passenger side.