Brake ABS Sensor rebuild

Ralf7732

Joined
May 27, 2026
Messages
12
Age
61
Location
Aachen, Germany
Bike
Sommer 462, ST-1100
Hi!

my name is Ralf, I am from Germany and have been riding a ST-1100 25 years ago and completed an IBA ride with it. Later on I dumped it into a ditch in Scotland. Sad day ...
I think the ST-1100 was the only vehicle I ever bought new. Everything else I own and owned was pre-owned :)

Went back full circle just now and bought a 1996 ST-1100. It is a bit of a project as the ABS light is on. On top of that the honk did not work (fixed by now), there is some noise from the front, and a bit of water dripping out of the exhaust pipes - just to mention the issues I know of.
Previous owner had a nice luxurious valve installed in the rear wheel. Filling up air there is simple now. But unfortunately this valve is hitting the ABS sensor cable with predictable results: ABS Light on, no error code (has been reset), ABS lights flicker when I turn the front wheel, they don't when I let the back wheel spin ... . So far, so clear (I think - remarks welcome!): rear wheel sensor bad.
Unfortunately I have no access to replacement sensors. I hope I can build one from "raw materials" from China.

There has been something on building an ST-1100 ABS sensor on Facebook - but I don't have access to the full article. Ordered 1GT101DC equivalents in China based on the headline of the article. It will take a while before they get here. Obviously I am not sure whether that's the right type. I will try to put my oscilloscope to work on my front sensor, so I can check in more detail ...

I also used the search, maybe I was too stupid. The article on diagnosing the ABS system was very helpful indeed, but obviously doesn't cover the "build your own sensor" topic.

In other words: I am still clueless Every tip and trick on how to get / build a sensor for the ST-1100 is highly appreciated!

Drive safely,

Ralf
 
A front or rear sensor will work except the wiring for one is too short for the other.

Be very gentle removing the sensor from the bracket. The sensor housing is very easy to break and an expensive repair.
 
Thanks for the hints! I got in contact with Alan from happybikes ...

My rear ABS sensor did come loose easily. As I had two (!) defunct ones (one blew my 10 amp ABS fuse) I had a closer look at how they are made.
I am under the impression that the cable is not mechanically connected to the sensor. It seems to me that a cleanly cut 3wire cable is just brought in ccintact with a similarily clean cut 3wire stump on the sensor. The little rubber element on top of the sensor is not just protection, it also ensures that those two pieces stay in contact. The litte cable tie on top ensures that the cable does not move out and does not turn ...
This construction sounds completely crazy to me - or is that a standard way of doing this?

And with this construction, I am not surprised that there are reports of blown 10amp ABS fuses due to bad sensors ...

I found a reference to one of the seemingly lost articles in Facebook:

Article [11] - ST1100 - Broken Front ABS Sensor Replacement Clone from Alliexpress | ST1100 Articles

1993 ST1100 ABS TCS (Early ABS System System) Broken Front ABS Sensor Replacement Clone Honeywell 1GT101DC from Alliexpress Hi, one of the things i have been fearful of with this bike is breaking anything to do with the ABS system or having a modulator fail, in NZ its a requirement if ABS is...
www.st-owners.com www.st-owners.com
Unfortunately the wayback machine did not catch this. Should abnone have a copy ... please post it.

And yes: The facebook article says that the 1GT101DC is plug-and-play electrically. I will report when they arrive.

Does anybody know, what signal is actually generated by the original sensor and how much current the ABS control unit pulls fron the signal line?
 
Update:
I ordered one sensor from Alan / Happybikes. He uses a more modern basic hall sensor (two-wire 7mA/14mA signal?) with some conversion electronics to fit it to the three-wire connector of the ST1100.

And I ordered 2 different types of 1GT101DC compatible sensors at Alibaba (5pcs + 4pcs). Did that to see how well delivery from China works (they don't seem to deliver to the US, Germany was no issue though).
Also ordered the ST1100 three-wire connectors from China. Instant find using Alibaba's picture search (well - at least that's what I hope for).
I assume these orders are minute for Alibaba - Alibaba is meant to be a B2B platform. But the service LOOKS great (again no actual product arrived at my door yet). I even received pictures of my actual 4 pcs and the final package before they send it out).

In the process of checking them, I will probably destroy some of these sensors, but:
If everything works out perfectly, I am heavily overstocked on them :-)

Again: Remarks welcome, will keep you posted ...
 
Got some material now:
- one complete sensor from Ala / Happybikes. To be tested
- also got the correct connectors from China in: 25 pcs each, one color only.
Will try to set up Alan's sensor directly with a connector (just crimping, no soldering). Nt sure though, whether cable length is sufficient.
Work on the bike itself will continue on the weekend ...
 
kiltman said:
If I recall correctly, the HappyBikes sensor can be spliced into the wiring harness from the original sensor, so cable length isn’t too critical.
Click to expand...
Yep, that is the way HappyBike told me.
But you have the wire and the new connector that will work too. ;)
 
I really don’t have facts to back this up, however, as an observation, maintenance is the key to keeping the ABS system functioning. A few years back the ABSI (1992-95) there were issues with the ABSI pumps failing, there is that potential on the ABSII pumps 96-2002. I believe due to dirty brake fluid. I’m a strong believer in changing and flushing the hydraulic fluid at least every two years. Moisture in the fluid can cause damage to the pumps.
The system also likes reliable voltage, keep your battery in a good state of charge.
Check the gap on the sensors, and make sure the sensors are clean.
 
This doesn’t answer any problem that you have described, but you might find it useful.

Discovered and checked on an ABS 2 model. I’ve never set eyes or hands on an ABS 1 version.
It a method to use the bike itself to check whether the sensor is sending a signal to the ABS control unit simply by spinning the wheels.

https://www.st-owners.com/forums/threads/st1100-abs-fault-finding.158284/


I also note that the ABS pump fuse will blow if there is too much brake fluid in the reservoir - perhaps as a result of topping up the fluid half way through the life of the pads, and later fitting new pads without removing the extra fluid. As soon as the pump motor whirs into life, the motor stalls and the fuse blows.
 
ABS is working, at least the light went out
:)
Everything behaved as described in the article about ABS problem diagnosis.

I got it to work with Alan's new sensor (Happybikes UK). Cable was long enough to attach my new connector directly - without soldering.

Result:
IMG_3525.jpeg

I have checked the signal using this test cable:
IMG_3524.jpeg

Signal looks like this on my oscar:
IMG_3529.jpeg

It seems to flip between around 0v and 4v.

On the China front:
51 Connectors arrived and seem to be good. One extra pair was included - I ordered "just" 50.
5 basic 1GT101DC sensors seem to have arrived, but at my home address, will check them next week.

IMG_3526.jpeg
 
The 1GT101DCs arrived in perfect shape.
Cable is too short, needs to be extended (which I personally do not like).
But I connected an old front-wheel cable (black connector) to it.
It seems
a) I connected it the right way (cables not color-coded "Honda-style")
b) the sensor works (ABS light blinks in diagnosis mode when back whell spins)

Sensors nicely slips into the bracket, but an adaptor plate would be required. Alternatively I could physically destroy part of the sensor case and screw it with just one screw. Never heard of a sensor that ever fell off, but there is sufficient talk about sensors that are difficult to remove ...
 
Mechanically, the new sensor does not fit right away. That was clear from the specs. But I think it can easily be fitted in:
The sensor as shipped looks like this: (first picture, from the specs)


It cannot be screwed into our brackets - the hole does not fit.
But if your destroy it around the metal insert, take the insert out and extend the hole a little bit "inwards" (with a Dremel or so), the screw fits. Yes: Only one screw holds it and there is not metal reenforcement anymore, but I can't imagine this matters. And at EUR 10,- per sensor - so what if one disintegrates: (second picture)

I protected the cable with a hose and crimped the correct connector to it. Cable is too short though - extension cable would be required. I believe I got the cable colors right, but I did not test this one.
If those cables were just longer ...
 

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