Modern Vespa

Hi. I have a 2018 Vespa GTS300abs model and the front brake lever was jammed solid with no abs light on or braking effect. Tried to bleed the system but no fluid coming through. Bled the caliper all good, bled the line down to the abs module, all good. No fluid coming out of ABS module. Hmmm. Tried disconnecting and reconnecting electrical plug, no joy. Looked up price of new module. Jeez! Ok, got out my heat gun and heated the whole module up with particular focus on black plastic housing where the solenoids are located. While hot I tapped the housing with a brass drift (mechanically percussed) and what do u know it passed fluid and I was able to bleed brakes normally. Whoo hoo! Change your fluid guys, regularly.

very interesting solution, have seen a few others on this forum (and the german forum) have the problem and replacing the unit.

thanks for sharing

I like to exhaust all options before I replace expensive parts 🤣

Just had precisely the same problem with my 2020 GTS. Like you, unenthusiastic about paying $1200 + tariffs + unknown wait time to have the part sent from Italy, plus dealer labor since a new module must be synced with the engine computer after installation. This could easily be a >$2K dealer repair all-in.

I pulled the ABS module out of mine last week and sent it to Module Masters in Moscow ID, the only folks I could find who said they'd be willing to at least take a look at it.

Will report back here on whether they're able to repair it. Failing that, I will try an ultrasonic bath for the solenoid block in brake fluid if I can get the electronic part separated, or your heat-and-impact technique if not!

The solenoid block ( black plastic part) is completely sealed on my unit so i was left with the only option that i have described. Please let me know how yours turns out.

Following up for others who may experience this brake problem in future: I just got a call back from the folks I sent my seized ABS module to: they WERE able to repair it and it's on the way back to me. Yay! Cost was $250 plus shipping… a HUGE savings over buying a replacement part from Piaggio. As far as I could find out, these are the only people in the US who are willing to repair Vespa ABS units (liability, I guess).

Highly recommended!

Module Master
Moscow, Idaho
(208) 892-0764
http://modulemaster.com

and

https://vespaforum.de/viewtopic.php?t=63598&start=15
"Glaubitz repaired my hydraulic block. It cost €200 net. It only took a few days (for the mail) and has been working flawlessly for 2,000 km." (google translate)

Glaubitz GmbH & Co. KG
Görlitzer Straße 53
02763 Zittau
https://www.ecu.de

Another followup…

The repaired ABS module on my 2020 GTS worked fine for a few months and then froze up again.

The repair cost was very reasonable, as described above, but considering the labor involved in removing/replacing thr unit and the difficulty of bleeding all the air back out of the system afterwards, I'm not sure I can recommend taking a chance on rebuilding these units after all.

If the cost of replacement (which must be done by a dealership) is too much to justify, the only practical recourse may be to bypass the ABS control completely for whichever brake channel(s) is/are frozen. I'm intending to do this to mine. This will require a couple metric bubble flare connectors and some brake line. Even if both channels are bypassed, my understanding is you still have to leave the ABS unit in place and wired up - the ECU requires it. Interestingly, mine never did trip an error light on the dash despite the malfunction.

Please keep this thread alive with photos as you proceed. Good information here!

You are correct that the abs pump needs to stay in place and connected, the abs warning light operates normally. I just used a brake line from an earlier non abs model to bypass the unit. Also the abs unit stores the VIN number for the scooter.

ECU needs it for ASR.
Dashboard also needs it for the speedo since iirc all gts with abs don't use a mechanical cable for speed (it's the abs unit that turns the signal from the sensors into actual speed values). ECU doesn't care about if the ABS unit has the VIN programmed in. Have heard of someone successfully using a 2nd hand abs unit without reporgramming.

Related: the ECU *can* also have the vin programmed in but all here in aus that I have seen have it blan. eg mine was blank (all of the 4 that I possess). Also think of the example of replacing the ecu, it doesn't care about the vin - I did this with no problems. also easy to change the vin in the ecu

Any theory on the original reason of fault on these modules?

They are Chinese.

I'd hazard that it could be several factors related to manufacturing:

- surface finish in the pump bores
- improper tolerances specified in design
- distortion of housing during assembly
- misalignment of components between assembly sections

This is all conjecture, since I don't have a pump to look at. Maybe someone should kick one over to Munro & Associates to test it down any perform an analysis.

Latest 300/310 ABS module is made in Thailand, I don't know if it's still made by Ate. Most failed modules I've seen were due to low mileage and / or not replacing the brake fluid biannually as suggested...

Earlier GTS with abs were ATE which is owned by Continental (known for tires). 300HPE era models show China on the sticker - not a criticism - they make both a lot of high quality and yes a lot of low quality.


Piaggio switched to Bosch for the GTS '2023' and newer. Bosch have many factories including in China, Thailand and even Russia. Can't see which on a sticker on the unit. Bit more digging suggests the Thailand factory is for motorcycle abs (as you say) - yet again not a criticism, love my Thai made YSS shocks.


I suspect fail causes are things such as:
* not changing brake fluid.
* never activating the abs by braking hard. I highly recommend occasional braking hard enough to deliberately do this.
* brake line issues such as the recall in 2021-ish leading to crap getting into the system, imaging the zinc/nickle plating on the ends flaking off into the inside and traveling down into the abs. Maybe there were some rare individual defective brake lines across a range of years without a recall.

PS, one of these days I'll hopefully add brake bleed commands for the ATE unit to my VespaDiag app, not so sure about writing vin to the abs.