ABS 1 Issue

[Erdoc48]

My 94 was on the road yesterday. Runs fine, but the ABS and TCS lights were flashing like mad, and this continued despite hitting the ABS warning shutoff multiple times. I changed the brakes recently without issue (just the pads) and had bled the system a few months back, also without issue. I’m assuming the brake MC isn’t overfilled as I was reading that if overfilled (and I guess over pressurized) it might screw up the ABS (when I changed the pads and depressed the pistons in the caliper, I had the excess fluid go out via the bleeders (speedbleeders installed and the MC is full with a solid feeling handle pull, and actually very strong braking). I interrogated the system and it seems it’s a code 3, so a front sensor issue…I cleaned the ABS/TCS switches with contact cleaner as recommended by UP, and cleared the codes. My ABS on the bike has always been a little flaky and sometimes would flash rapidly without known cause. Restarting the bike in the past usually helped, at least temporarily. So, here’s the question…if I try to troubleshoot (still have a few tricks like cleaning the contacts at the ECU and the sensor contacts) and cannot fix this on an ongoing basis and assuming the front sensor is defective and they’re not available any longer, is there a way to basically shut off the system, making it a non ABS bike such that I don’t get the flashing lights on the dash panel? I know this might be heresy to want to shut off a safety system, and I really don’t, but the lights when flashing continuously are a distraction, especially if I can’t get to the bottom of the issue.

Any thoughts, and thanks in advance.

 

[Uncle Phil]

On an ABSII, you can easily disconnect the lights behind the speedo/tach (remove the windshield, garnish, gray cover).
You just have to match the connector with the light (they are there so the speedo/tach assembly can be removed- bulbs do not appear to be removable).
I had to do this on a long trip when the ABS decided to get 'ugly' at the start of it.
I would presume the same option exists for ABS I.
You could also try pulling the ABS fuses (on ABS II there is a separate fuse block).
Hope one of those works for you if you can't get it sorted.
BTW, check your battery to make sure the connections are clean and the battery is good.
Low voltage will make the ABS do really funny things.
Also there is a company in the UK that has repurposed newer sensors that you can fit to the old plugs but I can't remember their name.
I believe @kiltman got some from them.

 

[Upt' North]

Erdoc,
I'm not a ABS type but if I was.......
Are the front and rear sensors interchangeable, if so swap em and see if the fault changes end.
Whether you can change out the ABS might depend on your local regulations but many in the UK are removing ABS from older bikes (mainly BMW's) as it's not an enforceable requirement.
Good luck fella.
Upt'North.

 

[Erdoc48]

I’ve been trying to be systematic and the first thing I checked was the fuses. They were good and the battery is near new. I’ll keep looking before pulling the dash lights (that’s the endgame I guess). Thanks for the tips.

 

[kiltman]

Here is the link for the ABS sensors that I purchased mine from.

https://www.happybikes.co.uk/

Yes the front and back sensors are interchangeable to troubleshoot.
The unit from happybikes is good for either the front or back. The kit includes the wiring, you will have to splice the connectors but instructions are included.

 

[Slydynbye]

2 More things to check
The distance from the ABS pickup to the ABS ring on the wheel and the connector that the ABS cable first plugs into, unplug clean and reconnect it.

 

[Erdoc48]

All great suggestions...won’t be nice for riding for a few days, so I have some time to troubleshoot.

 

[jfheath]

Check for wire brush debris on the senosrs - the faces are magnetic.
Check the pulsar ring for tiny cracks.
Check the air gap.

Once you have cleared the codes, you will never get another code until the fault is fixed. Why ? Because the system needs to be working for it to detect that the sensor has failed. And if it isn't working, the ABS will not arm itself.
So interchanging the connectors will not reveal the fault - becasue if a sensor is faulty, the system will not arm itself.

On the ABS II system, I came upon a diagnostic procedure - quite by chance. Maybe it will work on the ABS I system. Worth a try.

Retrieve the fault codes. Yes I know. Do it again.
Clear the fault codes - even if none are shown as being recorded. Just perform the necessary procedure.
Do NOT turn off the ignition.

Spin the wheels. The ABS light will flash if it is working (you're going to need help with this for the front wheel - you can start the engine and put it in gear to see the back wheel.). The ABS light doesn't flash if the sensor is faulty.

The question remains as to whether the fault is in the sensor or in the connectors/wiring. Now you can try the interchange method,

As I say - I know this worked with my ABS II. I don't know if it works with the earlier version.

The brakes work just fine without ABS. Paint or sticky tape deals with the light ! There might be an issue with MOT. Ours stipulates if something is fitted, it has to work.

If the sensors are stuck, do not under any circumstances try to tap them out of their brackets, no matter how gentle you think you are being. The brackets will snap.

 

[Erdoc48]

That’s sounds good…I’ll give it a try. Thank you all for the suggestions.

 

[Erdoc48]

One more question: I have the Kisan Tailblazer lights on both ST’s (for many years), so they flash and then are steady on when braking - do the rear lights affect the ABS system in any way (would a flashing tail light change the inputs to the ECU or sensors)? Just a thought and I doubt it matters, but I want to be sure.

 

[George]

Of all the ABS faults I saw on LipSTick, the only hard fault was a bad sensor on the rear wheel. Spliced on an aftermarket sensor after swapping in a borrowed stock sensor to confirm the problem. Fixed.

I have no info about the aftermarket sensor but except there is info here somewhere.

 

[Andrew Shadow]

One more question: I have the Kisan Tailblazer lights on both ST’s (for many years), so they flash and then are steady on when braking - do the rear lights affect the ABS system in any way (would a flashing tail light change the inputs to the ECU or sensors)? Just a thought and I doubt it matters, but I want to be sure.

No effect.
ABS functions independently of the lighting system.

 

[Erdoc48]

No effect.
ABS functions independently of the lighting system.

Thank you!

Also, this AM, I removed the right brake caliper after bleeding my front brakes (I didn’t take the cap off first as I didn’t want brake fluid all over-bled some then removed the cap of the MC) and bringing the fluid to the appropriate level (I wasn’t sure if too much fluid in the MC can cause ABS issues -I did a full brake fluid change months ago and just recently put in new pads, in so I assumed I might have too much fluid in the MC with the new pads, even though when compressing the pistons, I let the excess fluid out via the bleeder, but maybe not enough flowed that way and some went back up the brake lines- who knows?). I cleaned the sensor carefully (some dirt but no metal filings seen and pulsed ring appears intact- no broken teeth), reassembled it all and went for a short ride to fill the tank (only ~ 20 miles)- no ABS/TCS lights so far, so for now, I guess I’ll just wait and see- if it comes back, I’ll have to do more analysis with a volt/ ohmmeter and take the plastics off under the windshield to access the harness and ECU. I really hope I don’t have to do all that. Also, the sensor to pulse ring has a fixed gap, and it looked pretty tight (so appears in the 0.8 +/- 0.4 mm spec)

But again, thanks for all the replies!