12 replies to this topic

[Nog]

I've noticed the ABS is barely doing anything on my niner rear brake.

 

Have now twice fishtailed along in wet conditions with the ABS just ignoring the fact the rear has locked up.

 

I was 'testing' it today and it barely fluttered slightly once, but generally just didn't release.

 

I'm wondering if there's some air of blockage in the pump and it needs purging/priming.

 

The rear brake is very effective otherwise, grabs but easy to lock in the wet (new disc and pads).

 

The ABS light on the dash comes on with ignition and then goes out shortly after - my other bikes ABS lights only go out once the bike starts moving to confirm they've detected the sensors, but I'm not sure the old TDM system is that sophisticated.

 

Anyone had any dealings with the niner ABS unit at all?

[Studley Ramrod]

Just moved yer topic Nog 🙂 also informed Mr Henty

[Muppdog]

Hi,
Got the same issue.(Lorry-) Mechanic at work thinks its the sensor given up the ghost. Probably right. Tried to remove it, the garage tried but not shifting. Soaking, levering, hammering, That was years ago. Just riding without rear ABS since. No issue. Better for off-roading, too!

[Nog]

I would have thought it would throw an error up if the sensor had given up though - apparently the system runs a check for 2 seconds on ignition, and the light should go off, which mine does ok, but then the light comes on if the wheel sensors throw a wobbly.

 

I'm checking the ABS supplement manual to check on possible issues, but it could well be I also have to accept no ABS on the rear - not the end of the world, rode non-ABS bike for many years without issue.

[Snowbird]

As long as the light goes off at mot time.

[Catteeclan]

Think the TDM does a circuit check before the light goes out and that's it. You'd have though Yam would throw a code if the rear isn't going as fast as the front continually.
Mandis CBF has to get up to around 5mph then the light goes off.

[Nog]

I've been reading through the manual and it appears there's no special bleeding procedure, just the usual we'd always do, but the hydraulic unit can be tested once complete.

 

It needs the Test coupler adaptor (part 90890-03149) which Fowlers has for only £8, but it really is just shorting two wires which a guy covers here:

Test and Maintain your ABS System | Yamaha FJR Motorcycle Forum (fjrforum.com)

 

 

The test procedures he covers, and it can be done with the bike on the centre stand with the engine off, so i'll give this a go at the weekend.  Hopefully will at least show if any problems, and maybe even help purge the unit a bit.

[Studley Ramrod]

Yeah, shorting 2 wires, rings a bell. 👍

[Nog]

So I had a go at it last night - found the connector behind the ABS ECU in the right fairing panel, shorted out the top two wires and ran the tests.

 

Test 1 - make sure kill switch is off so the bike can't start, battery needs to be well charged so best to put on a charger/tender.

Turn on ignition and hold down start button for 5 seconds or more.  Let go and then brake with both front and rear at the same time and hold.

ABS motor fires up and pulses the front and then rear in turn for a few cycles.  Lever and pedal should 'pulse' as the systems pumps.

 

Test 2 - Kill switch off etc as above, but this time hold the brakes on with ignition off.  Then keeping the brakes fully on, turn the ignition and keep holding.  The pump will again go through it's cycles.

 

The tests worked fine and the motor ran, but the 'pulsing' wasn't what I was expecting and it felt more like just a vibration and quite weak, so I'm thinking years of never operating has left the ABS pump full of older and older brake fluid gunging everything up, and it's not really releasing pressure as it should.

 

The problem is, when actuated, it doesn't move the fluid much, as the bypass that releases the pressure on the brakes is just a bypass section and as it's all a sealed system, the fluid can't really travel anywhere, just releases the pressure on the system.

 

So my thinking is, if I run the tests and then bleed the caliper as the pump is pulsing, it should (by my logic) push fresh fluid into the pump as it opens/closes the solenoid.  Might allow the old rubbish to clear and then the new clear out any blockage/debris and get it working again.

 

Who knows, will try and see.  At the worst the system is simply a non-ABS bike, which I've ridden for decades anyway, so I'm not too concerned about that, just be nice to get the system working if I can.

[Studley Ramrod]

Good to know Nog 👍 thanks for sharing.

[dablik]

Yes thanks for sharing, be handy for my bike also...

[Nog]

Just an update - I tried bleeding the system as the solenoid was engaging - no difference, but hopefully some fluid has been moved through the system.

 

Maybe it'll work on the road, but I'm not sure. Apparently the unit is non-serviceable from what I can tell, so I'll just ride knowing my ABS is pretty well non-existent.

[Studley Ramrod]

👍