OP
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Piaggio mp3 250ccm 2006.
Joined: UTC
Posts: 3
Location: Serbia
 
Lurker
Piaggio mp3 250ccm 2006.
Joined: UTC
Posts: 3
Location: Serbia
UTC quote
Hi all,

I've been browsing this forum for some time and I must say I saw some helpful answers.

Now, I have a problem with my Piaggio mp3 250ccm 2006. and, with my knowledge, it's related to a seat and/or speed sensor(s).

Long story short: I am able to engage the roll-lock, however immediately after, the red light pops up and the scooter is limited to 2000 rpm. The stabilization is not being disengaged atomatically when I try to start (give gas). I am able to release the roll-lock by double-tapping the switch to the right. No beeps, no other errors.

Ok, I realize that this has something to do with the seat and/or speed sensor(s), so please bare this in mind.

It all started with the broken speed sensor wires on the right wheel. They both snaped just right next to the socket, leaving a milimeter of wires, not giving me a possibility to recognize wire colors. I managed to solder the two wires back together, however not sure if I matched the original polarity.

QUESTION 1: Does the speed sensor polarity matter?

Second thing: I noticed that the previous owner soldered a 3kilohm resistor onto the wires below the seat. I have tried replacing it with a 3.4kilohm resistor, also tried without the resistor, with/without being plugged into the seat socket. With the resistor soldered between the two wires (not connected to the seat) I get a reading of 1.9kilohm on the wires that go to ECU. The resistance measured on the wires comming out of the seat is ~17kilohm. I tried measuring the seat resistance while slowly pushing onto it, but the value didn't change. When ignition is set to ON, the reading from the wires comming from the ECU is ~5V. I have taken off all the covers and I don't see any damage done to the wires.

I appreciate any feedback that will help me solve this problem.


Damir
@jimc avatar
UTC

Moderaptor
The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
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Posts: 43890
Location: Pleasant Hill, CA
 
Moderaptor
@jimc avatar
The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
Joined: UTC
Posts: 43890
Location: Pleasant Hill, CA
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I doubt very much that the speed sensors are polarity sensitive. A two-wire sensor will be a coil with a small magnet inside, and when a tone wheel (ABS) or other varying ferrous material passes by them (say the bolts holding a wheel on), a small variation in the magnetic field inside the coil will occur. With a small current fed through the coil, the voltage across it will then vary. This is used to do the required computation.
OP
UTC

Lurker
Piaggio mp3 250ccm 2006.
Joined: UTC
Posts: 3
Location: Serbia
 
Lurker
Piaggio mp3 250ccm 2006.
Joined: UTC
Posts: 3
Location: Serbia
UTC quote
Yes, I think that the speed sensors could be eliminated from consideration regarding this issue, however I thought it should be mentioned, since the seat sensor and both the speed sensors share one line to ECU.

Ok, so it leaves us to take a closer look at the seat wirings. I will examine them tomorrow again and post an update. Hopefully with some good news.
OP
UTC

Lurker
Piaggio mp3 250ccm 2006.
Joined: UTC
Posts: 3
Location: Serbia
 
Lurker
Piaggio mp3 250ccm 2006.
Joined: UTC
Posts: 3
Location: Serbia
UTC quote
UPDATE:

As I've read one of the post replies, I can confirm that putting another 3K resistor in paralel, DOES bypass the seat sensor.

Thanks for the help.


Damir
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