ABS Light, No rear brake

[VPS1]

Hey guys, rode the S10 to work this morning and took a turn a little tight and noticed I got a bit of Traction Control Light flicker....then maybe 200 yards later I have an ABS light and notice the rear brake pedal will not move. Still have hand brake. Stopped and the hand brake is not working the rear at all, the rear is not dragging. ABS comes on a few moments after restart. 2012, 34,000 PERFECT miles.....Where do I start? No warranty at this point.

 

[EricV]

Have you done any service to the bike prior to this?

6 years would be a long time w/o a brake fluid change... There have been similar reports on the forum of this type of failure. Different fixes. I'd check for any debris in the rear caliper first, then probably try to flush and bleed the entire system, including a cycle of the ABS pump using the diagnositic connector method before I moved on to other ideas.

I hope it ends up being easily solved.

 

[VPS1]

I flushed it in 2015 and bled it with new pads in 2017. The fluid looks clean, it’s not dark. Not new but not dark. When I flushed it I did the ABS pump with the jumper wire. I pushed hard on the brake pedal and it moved, not smooth then smooth. I put the jumper wire in and did the ABS pump 4 times. Brake pedal is still not right but rear brakes work with pedal but they don’t when front brake is pulled. When I pull front brake I can hear a sound coming from the abs pump, like fluid with air moving. Both front and rear brakes have plenty of fluid. I’m thinking I will flush and bleed then do the abs pump a few times and bleed again, see what I get. Could it be a sticking rear master cylinder?


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[gv550]

With the bike stationary and engine not running, the rear brake will not be applied with the front brake lever. The vehicle must be moving before the unified braking feature is enabled.

 

[EricV]

Starting to sound like there might be something going on with the rear caliper piston. I think you are on the right track, and have a good plan. Always smart to eliminate the easy and cheap things first! If your current plan of attack doesn't change the rear brake feel, and you already did the silly stuff like lube the brake pedal, then I'd pull the rear caliper and make sure the tension arm isn't wonky, then look at the piston to see if it's dirty/damaged.

Odd things sometimes happen. I had a rock, (I think), score the side of my brake piston once. Would hang up and chewed up the seal a bit before I pulled the caliper, carefully pushed the piston out, cleaned everything and polished the mark on the piston, then put it back together and did another flush/bleed. Was fine after that. In hindsight, I might have been able to tidy it up w/o fully removing the piston and could have avoided another flush/bleed.

 

[VPS1]

Sitting in the garage, today the rear brake feels 100% normal, took her for a spin and the first time I push the pedal, it’s hard and then moves.... rear wheel locks up and ABS light comes on. Same as yesterday. When the rear brake was working before I rode it, it was totally smooth and normal. Stopped rear wheel spin and then releases nice, no drag. I am thinking either the rear master cylinder is bad and only shows it when the abs pump starts unified braking or the abs pump is bad. Do I rebuild the rear master cylinder, or just head to Yamaha?


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[EricV]

Not sure about the ABS pump or light. I do wonder about the proportioning valve for the unified braking though. Unified braking only works when the bike is running and moving. The wheel locking up and ABS light could be incidental to the problem.

 

[Cycledude]

Wheel bearings good ?

 

[VPS1]

To clarify, when I rode it the brake pedal was hard then as I pushed it breaks free and slams on the rear brake, locking up the rear wheel till I let off. This brings the abs light on. It happened after I use the front brake. My wheel bearings were fine at the last tire swap, 3500 miles ago.


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[Cycledude]

Well the reason I mentioned wheel bearings was mine went out at 45,000 miles and the first indication I had that something was wrong was the rear brake wasn’t working right .

 

[VPS1]

Clycledude, I get that. If the bearings allowed the wheel to wobble that would affect the brake, this is different I think. But I will see if there is ant bearing movement just to rule it out. Did your ABS light come on?

 

[Wrathchild]

The wheel bearings would make the rear brake not work by having wobble which would push the pistons back into the caliper, this would make the pedal drop like a stone when you first hit it, with basically no actual braking force, as the pads are pushed back into position. It wouldn't make the pedal hard.

This sounds like something is sticking, like some crap in the line/caliper/valve somewhere. If the ABS wasn't working the brakes should work as normal, just without the anti-lock function when you slam them on.



Also, I still don't get having to use a connector to cycle the ABS. Just go slam the rear brake on lol. Come in hot, go HARD on the rear brake. Boom, ABS cycled. If you can't make it kick on like that, brake hard with the front to shift the weight forward off the rear tire and it should kick it on easy.

 

[EricV]

One advantage to cycling the ABS with the connector is you can hear it working, which may be important in this case. Some riders don't know what the ABS feels like at the lever/pedal. If you're using the connector you should be able to tell if it's working, and hear any oddities, if present.

 

[VPS1]

Eric, can you describe the sound of it working?


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[EricV]

Eric, can you describe the sound of it working?

That's a great question... I can't. My normal riding has me engaging the ABS on a relatively regular basis by deliberately braking hard on gravel to do so. I like to use front and rear, in part to keep my reactions good when/if I do it in panic mode. The brake lever and pedal pulse noticeably when you do this. Because of this, I haven't used the diagnostic connector trick when flushing/bleeding the system.

That said, I'm due for this maintenance task, so maybe I'll try the connector this time to see what sound it makes.

Hopefully someone else that's done this can chime in with the noise it makes. I would expect it to be a chattering sound of the solenoid valve cycling back and forth in the valve.

 

[VPS1]

I get that, the ABS module made noise, and it did last for about 10 seconds or so. When you have the jumper in and pull front brake and push rear brake then starter button...do you hold both brakes? I did not hold them while the pump cycled. Wondering if I am doing it wrong?? It just did not clearly hear anything that was front, then rear, then front. Re-reading everything, I think I may have to hold both brakes as it cycles.

 

[EricV]

There is only one pump, just multiple lines into and out of it. It is necessary to hold BOTH the brake pedal and lever down while turning on the main switch. When the kill/run/start switch is turned to ON, a single pulse will be generated in the brake lever, brake pedal and again in the brake lever, in this order.

 

[VPS1]

Thanks, I was letting go of the lever and pedal....I will give it another go tonight. It does make noise when then aren't pulled/pushed.

 

[MikeinNZ]

New to S10’s but have a rear brake problem myself so have a good understanding.

You need to keep pressure on the lines when cycling the abs so when the abs valves release pressure, the air in the lines moves through to the damping chambers and back to the brake lines.

If I use the front lever first (at speed) and then the back brake the pedal feels harder than normal as the abs pump is already presssurizing the rear through the unified braking system. If I push harder on the back pedal the rear will lock with very little feeling on the pedal.
I would give it a good bleed, both front and back then cycle the abs. Do the process at least 5 times. Use a clear hose so you can see when your air free.
If the abs light is still on or occurs again it looks like abs pump
If the rear brake feels normal and is releasing without dragging on the centerstand there can’t be anything wrong with the cylinders except for maybe air in the lines causing the abs pump to fault.
My rear brake keeps turning to mush when the front is used first as I am hoping the abs pump is sucking air past worn seals in the rear master cylinder. Waiting on a seal kit to arrive.

 

[EricV]

There are two tests listed in the FSM for the Gen II bikes. Not sure if this is true for the Gen I as well.

FSM 2014/2015 Gen II page 4-77-79 shows two tests.

Hydraulic unit operation test 1: This test checks the function of the ABS after the system was disassembled, adjusted, or serviced.

Hydraulic unit operation test 2: This test generates the same reaction-force pulsating action that is generated in the brake lever and brake pedal when the ABS is activated.

Two people are necessary to perform hydraulic unit operation test 1.
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1. Place the bike on the centerstand.
2. Turn the main switch to OFF.
3. Remove the rider seat, adjuster, right side cowling.
4. Verify battery voltage. Lower than 12.8v means you need to charge the battery first.

Note that if the battery voltage is lower than 10v, the ABS warning light will come on and the ABS will not operate. (I didn't know that!)

5. Bridge the pins in the test connector, ( LINK ), Blue and Black. (full write up at the link by 2daMax on a Gen I)

6. Turn the main switch ON while operating BOTH the brake lever and foot pedal simultaneously.

TIP - It won't work unless both brake pedal and lever are pressed at the same time when the main switch is turned on. (note that if the ABS warning light is not flashing, the test pins are not bridged.)

Do not push the engine start/run/kill to start when turning the key on or the test will not begin.

7. Check: Hydraulic unit operation. When the main switch is turned to ON, a single pulse will be generated in the brake lever, brake pedal and again in the brake lever, in this order.

The second person should be applying rotation force to the rear wheel to see that braking force is released for 0.1 second allowing brief rotation.

Notes: If the pulsing is felt in the order described, all is good. If it's felt in the rear before the lever, that usually means incorrectly connected lines. Unlikely for most of us.

If the rear braking force is not released briefly during the pulsing of the pedal, but is during the pulsing of the lever, again, check the lines are correctly connected to the ABS pump. Again, not likely unless you've just replaced the pump.

If everything is normal, delete error codes.

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Hydraulic unit operation test 2.

1. Place the bike on the centerstand.

2. Check the following: Engine stop due to side stand operation.
a. shift trans into gear and extend the side stand.
b. turn kill/run/start switch to ON.
c. Push the kill/run/start switch to start and check that the starter doesn't operate. If it does, you have side stand switch issues. Sort that first.
d. Turn the main switch OFF.
e. Retract side stand.
------------------------------------------------
3. Remove rider seat, etc.
4. Check battery voltage. Must be over 12.8v. If not, charge batt.

5. Connect test coupler as before.
6. Extend sidestand.
7. Turn the main switch ON.
8. Push the 'start' side of the start/spot/run switch for at least 4 seconds.

NOTE: Do not operate the brake lever or brake pedal.

9. After releasing the start switch, operate the brake lever and brake pedal simultaneously.
10. A reaction-force pulsating action is generated in the brake lever and continues for a few seconds.

TIP - The reaction-force pulsating action consists of quick pulses.
Be sure to continue operating the brake lever and brake pedal even after the pulsating action has stopped.

11. After the pulsating action has stopped in the brake lever, it is generated in the brake pedal and continues for a few seconds.

12. After the pulsating action has stopped in the brake pedal, it is generated in the brake lever and continues for a few seconds.

NOTE: Check that the pulsating action is felt in the brake lever, the brake pedal, and again in the brake lever, in this order.

If it's in a different sequence, something is hooked up wrong.

13. Turn the main switch OFF.
14. Remove the test coupler.
15. Turn the main switch ON.
16. Shift the trans into neutral and retract the side stand.
17. Check for brake fluid leakage around the hydraulic unit.