355 speed sensor location?

I've never seen actuator teeth bad, but the shock gear absolutely can be, and why I mentioned using some magnification to inspect the gear closely. If even a part of the gear on top of the shock is missing the actuator cannot "grab" it and will spin freely, causing the suspension light.

Certainly could be an intermittent actuator. If the speedo is not intermittent, I am more inclined to think it is an actuator issue than speedo sensor.
At the minimum, I would at least go through and clean all the plug connectors on the speedo sensor and actuators. And make sure each actuator is properly seated.

 

Drove around again today for 15 min. Same deal. No check engine light. Speedometer works. Suspension light still on. I have another set of actuators I can try from my other 355. Can pull the speed sensor from that car as well if need be.

Just want to figure out quickly what’s going on before wasting time/money ordering parts. Going to put car back up on the lift and see what’s going on with the sensor.

 

Will a bad Bilstein ECU trigger a suspension light?

 

Yes it will.

 

I guess it’s time to put the FHP ECU in.

 

So I pulled the rear actuators from my other 355. Double-checked all 6 actuators and they all spin. I now have the rear actuators from my other 355 on this car. Didn’t care to swap the fronts yet as that is a bit more difficult, but my front actuators spin. All actuators are seated as low as I can possibly seat them with the pin locked. Probably checked this 10 times.


I read in another thread shaft on dampers could possibly too stiff to spin as I did have all 4 dampers rebuilt. Not sure what a solution would be for this if it is the case.

Just drove around again for 15 min. Lights still on.


I will swap out the Bilstein ECU.

 

The actuators can be broken internally but not be noticeable when off the car. They can spin and try and centre but once mounted the broken internal will not have sufficient grip on the adjuster gear to actually turn the shock shaft.

 

Can a dealer confirm on a 2.7 which corner actuator is malfunctioning?

 

Yes the SD diagnostic tool will confirm.

 

Swapped Bilstein ECU to brand new FHP ECU. Drove for 15 min. Light still on.

Next step. Swap out front actuators with my other 355. Lift car and clean speed sensor. If that doesn’t work, I will swap speed sensors.

 

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I'm not sure why but in the 2 cases I have experienced failed speed senders, they work for the first few kilometres travelled, and stop after a certain point. It was almost uncanny for my own car where it would stop pretty much at exactly the same point in the drive that I regularly do.

 

A speed sensor on the verge of failing, but speedometer still works would trigger suspension light and stay on?


I do find it suspect my CEL was speed sensor related, but now I can’t seem to get it to show back up.

 

From memory the suspension light only went on when the speedo would stop reading. Once its not getting a speed reading the ECU would trigger the light.

 

Pulling up an old thread from F355Bob regarding 4123 code. My experience is similar with minor differences.


https://www.ferrarichat.com/forum/threads/keep-getting-code-4123.280303/


In his first post he says he’s getting “SDL 5-8 at idle,” but if he blips the throttle it goes away. I believe he might have miswrote SDL instead of CEL as he later mentions CEL in the thread.


4123 is a “speedometer signal” code and according to the manual for 2.7. Some codes don’t show up during “use,” which I’m assuming driving or blipping the throttle (code goes away), but if just idling, sometimes it shows up.

I’ve only seen the CEL 1-4 (for 4123) show up during idle in my case. I haven’t seen it pop up while I’m driving or since. What’s odd is I had a CEL 1-4, while F355Bob had a CEL 5-8 for the 4123 code. Why would a speed sensor code be attributed to a specific bank?


The CEL has since disappeared, but still shows up if I pull codes similar to Bob’s experience. However, we both did not experience speedometer issues (at least not yet in my case). Car also seems to run normal except I have Suspension Light on.

I believe Bob also ran after-market Moton suspension, so suspension light might not have shown up or mattered to him.

We both have early 95 355’s if that matters.

 

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My diagnostic method was to get one known good actuator and move to through each position, going for a drive after each position swap, and hoping the light went out. Assuming gears were good, I would figure out the bad one. Of course the car could have more than one bad actuator, which then points to your method of swapping out two at a time.

 

How long of a drive are we talking here before the light goes out? I assume a light only goes out after a drive if corrected?

 

Apparently 4123 was driving Bob crazy.


https://www.ferrarichat.com/forum/threads/this-is-crazy.340411/#post-140877307

 

The speedometer processes the speed sensor data and sends it to the instrument pointer (needle) drive. It also sends it to a divide-frequency-by-two circuit in the speedo and then distributes it to vehicle systems (suspension, F1, motronic ECU/s, etc). It's possible your speedo dividing circuit (or wiring) is playing up.

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I'd still be trying to replace the sensor first. Easier and cheaper.

 

Yes, when corrected the light would go out after a short time.

 

@Qavion

32mm deep socket (unmodified) to remove speed sensor did not work. Standard length for deep socket is short by roughly 10mm as the plug stuffs the socket preventing it from reaching the speed sensor to remove. If you find a deep socket much longer, you’ll run into space issues fitting a ratchet. Basically, you need to find a deep socket not far from 10mm longer than the one I just bought or you’ll have fitting issues. I’m not gonna search the planet for that deep socket .


Just responding to an old post you made in another thread where you were pondering if a deep socket would work.

 

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Thanks, but I made up my own socket with cutout. I think some folks just cut off the old wiring and remove the sensor with a deep socket and use a regular spanner to refit it, but seeing as it is so valuable and you don't know if it's broken, you may have to come up with an alternative solution.

Similar to this:

https://www.ferrarichat.com/forum/posts/145313077/

https://www.ferrarichat.com/forum/posts/145337234/

 

Socket with a cutout seems to be the best solution. Wrench didn’t look plausible to me with lines around the area still in place.



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