Rear Pedal to the floor

[jfheath]

6mm cap screw. I attached that ground wire, cleared the ABS codes and started it up. On the center stand I put it in gear and revved it (had to get it up to 6mph right?). I turned it off and checked the code.... Blinks were "long... Short" then "long... Nothing". For kicks I checked the ABS fuses... All good except the bottom 20A pump motor fuse. I didn't have a replacement so I haven't replaced it and re-run the test.

The system cannot initialise itself until it can verify that both wheels are turning at the same speed - and for that, you need to have the bike rolling on the ground at more than about 5-6 mph. So putting it on the centre stand and revving it in gear, won't achieve anything, except for the obvious satisfaction of hearing that 1100 engine purring into life !

There are two codes stored in the system, which when retrieved are indicated by series of short flashes. The two codes are separated by a longer flash. So Long ... Short ... Long ... Nothing means that the first fault recorded is code 1, and that there is no second fault recorded.

Code 1, supposedly indicates the front crank angle sensor. But if the fuse has gone and it isn't turning, then perhaps you might expect that, although I would have thought a code 2 for rear sensor or a code 3 or 4 for the pump would have been more appropriate. But you have an earth lead detached, and all sorts of funny things can happen when earths are missing.

If there is a fault in the cycling sequence, which happens when you turn on the ignition, then you can expect a fault to be recorded at that point - although the manual says to ride the motorcycle as well.

[IpswichST]

Ahh... you see, sometimes the obvious doesnt jump out at you.

The system cannot initialise itself until it can verify that both wheels are turning at the same speed - and for that, you need to have the bike rolling on the ground at more than about 5-6 mph

Of course both wheels need to be turning... there are sensors on both. I am learning more and more as I ask questions and read. Sorry if I post frequently... just anxious to understand.

[jfheath]

I am learning more and more as I ask questions and read. Sorry if I post frequently... just anxious to understand.

Hey - don't be sorry for asking questions !! How else to find out ?

[IpswichST]

Well... I went for a ride on the bike at lunch time. Put a new 20A fuse in, cleared the code and went for a ride. The ABS light blinked the whole time I brought it back checked the codes and got : Long - Short. #1. No other codes. BUT.. that 20A fuse was popped again. Im gonna open the service manual and see what I can find.

Ok.. Following the flowchart in the service manual I have followed it to where it tells me to "interchange the front and rear pump motor relays with each other". Of course they are buried. Is there an easy way to get there????

ABS Gurus... What do you think is happening with my ABS system? Could on of those relays be the problem AND popping that 20A fuse also?

[jim'll break it]

A popping fuse would lead me to suspect either a short circuit on the abs supply wiring or a pump motor overload,
its possible that the pump has seized causing overload on the wiring, the abs cant see the pump turn so maybe thinks the angle sensor is at fault.
Trace the voltage through the relays(afaik they are under the top fairing) and see whats going on at the pump.
Could be worth powering the pump directly(through a fuse) and see does it work ok

[jfheath]

A popping fuse would lead me to suspect either a short circuit on the abs supply wiring or a pump motor overload,
its possible that the pump has seized causing overload on the wiring, the abs cant see the pump turn so maybe thinks the angle sensor is at fault.

I'd go along with that. Does the fuse blow when the sensor connector is not connected ?

Trace the voltage through the relays(afaik they are under the top fairing) and see whats going on at the pump.
Could be worth powering the pump directly(through a fuse) and see does it work ok

Take care with that. I have just been reading a manual for a Post-95 model, and one of the tests is to check the voltage between the pins on the sensor connector which is attached to the harness. It reckons that when the ignition is on, the voltage between the pins should be 4.5 to 5.5 volts. So take care not to confuse the crank angle sensor connector with the pump connector ! It appears that the motor connector is a 4-pin.

The relays seem to be the same as the headlight relays, so if you suspect a relay problem casuing the short, you can interchange them.

[IpswichST]

Could be worth powering the pump directly (through a fuse) and see does it work ok

Never done this. Is it possible to walk someone through this?

check the voltage between the pins on the sensor connector

Sensor connector? Are you referring to the relay? or the plug that attaches to the motor?

Im up for trying these troubleshooting suggestions. Im just new to all these systems and am unfamiliar with what I am supposed to look for. Thanks so much to everyone and their help!

[jfheath]

I am not an expert on doing anything with the modulators, but I do know that there will be 2 sets of leads, and both of the leads will have connectors. One of the leads will provide power for the motor, the other lead will be to provide information from the crank angle sensor to the ECU (the bike's computer, or electronic control unit). I found this photo using a google search for ST1100 ABS Modulator images - I can't tell you if it is the front or the rear modulator, or from which bike it came, but it looks familiar !

The motor seems to be the cylindrical lump sticking out to the right. Near it is a black electrical connector attached to the side. The wire at the left hand end, I would guess is the connection for the crank angle sensor.


You will be able to verify these assumptions if you look at the circuit diagram for your bike and compare the colours of the leads that you have on your bike.

You are getting a blown fuse - probably as a result of a short. Possibly as a result of a stuck motor. So before applying power to anything, I would get a multimeter set to ohms and measure the resistances across the connectors to find out if there is a short anywhere. And if that connector on the right of the picture IS the one for the motor, check across those connectors too. You can expect some resistance, but there should not be a short.

A layman's view of what this unit does - the modulator sits in the hydraulic system and the brake fluid flows through it. A cam-like device sits inside a reservoir of fluid and this cam is able to rotate under control of the motor. As it turns it releases pressure on the braking system and then re-applies it. Very rapidly. This is what causes the pulsing that can be felt on the brake pedal of a car or on the brake lever of the motorbike when the ABS kicks in.

What is important is that this cam is set at a position in which as soon as it turns, it releases pressure on the brake fluid. So the crank angle sensor is there to inform the ECU of how far around its rotation the cam has turned. When you turn on the ignition, the motor rotates the cam and stops it at the correct position, ready to ride. Hence the whirring that you should hear from the modulators as soon as you turn on the ignition.

PM sent.

[Firstpeke]

Lots of good stuff on here!

I would suggest that you may want to look up one of our members on here by name of Norm from Chilliwack BC.

He has refurbed a number of modulators for folks on here and is very good at it!

http://www.st-owners.com/forums/show...dulator-Repair