Hill Desent

[d2dave]

I have just finished doing "Option B". I have bled the brakes manually and with Nanocom. I seem to have a good pedal. Traction control and ABS appear to be working ok.

How can I test HDC as there are no hills for miles at my place. I have memories of trying on a flat road and it pulled up the vehicle. When I now try it on the flat, I can hear the pump kick in but there is no effect on the brakes.

The green light on the dash is illuminating.

[SiddersC]

Engage low range, drive down the street about 20kph, release throttle and HDC should activate and slow you down

[d2dave]

Tried that. I can hear the pump working but it did not slow me down.

[SiddersC]

If you can hear the pump working I would say all is ok?
You may not have enough momentum to feel the full effects

[OffTrack]

HDC should slow you down in a fairly obvious way. Depending on which gear you are in target speed is 5-9kph with no throttle. Braking becomes more aggressive the closer you get to the target speed, but will cease once you get below it.

You can use throttle to modulate the target speed up to something like 50kph. It's worth having a drive with HDC engaged just using the throttle to control speed/braking. It's not something you'd want to do all the time as the abs racket gets a bit tiresome but it gives you a pretty good idea of how hdc works. You should find that at above 2000rpm with 0% throttle the torque convertor will lock to assist braking.

[d2dave]

HDC should slow you down in a fairly obvious way. Depending on which gear you are in target speed is 5-9kph with no throttle. Braking becomes more aggressive the closer you get to the target speed, but will cease once you get below it.

You can use throttle to modulate the target speed up to something like 50kph. It's worth having a drive with HDC engaged just using the throttle to control speed/braking. It's not something you'd want to do all the time as the abs racket gets a bit tiresome but it gives you a pretty good idea of how hdc works. You should find that at above 2000rpm with 0% throttle the torque convertor will lock to assist braking.

I took it for another drive last night and it does seem to be working. Before I bled the brakes I did a bit of research on this. My bleed did not seem to be like anyone else's. I used a bit less than one litre of fluid. I bled the brakes normally and then used nanocom to run the ABS pump. When I then re-bled the wheels I got no more air.

I have a good pedal and the brakes work fine. If there was air still in the ABS would it not eventually find its way out and then produce a spongy pedal?

[OffTrack]

I've posted up a nanocomised version of the wabco abs bleed process in a recent thread.

See here:

http://www.aulro.com/afvb/showthread.php?p=1881028#post1881028

You might be ok as is but one litre doesnt seem right for a full bleed.

[d2dave]

I've posted up a nanocomised version of the wabco abs bleed process in a recent thread.

See here:

http://www.aulro.com/afvb/showthread.php?p=1881028#post1881028

You might be ok as is but one litre doesnt seem right for a full bleed.

This is the the info I used. Below is a copy and paste.
Manual Bleed Procedure with Electronic Control Equipment

NOTE: The electronic control equipment must be capable of actuating (energizing) the outlet solenoid valves for each wheel for approximately 10 seconds and activating the pump of the modulator. The inlet solenoid valve should be open (de-energized). The Meritor WABCO Diagnostic Controller can be used to do this.

1. Apply the parking brake and chock the tires. Turn the ignition OFF.

NOTE: The ignition must remain off for the initial bleed procedure; energizing the unit during bleeding must be impossible.

2. Perform brake bleed procedure for wet module, bleeding the circuit and master cylinder if required prior to connecting electronic control equipment. Use Pressure Bleed Method if equipment is available; if not, use the Manual Bleed Method.

3. Install electronic control equipment to ECU, or to the modulator assembly and pump.

4. Turn ignition switch ON or power electronic control equipment.

5. Push on brake pedal with maximum force (firm pedal) and hold.

6. Activate the pulse function on the electronic control equipment starting with the longest brake circuit, typically the rear.

7. Release brake pedal for 5 seconds and activate the pump of the modulator for approximately 5 seconds.

8. Repeat Steps 5 through 7 three additional times.

9. Perform manual bleed on appropriate wheels.

NOTE: To perform a manual bleed, follow Steps 2 through 8 under “Manual Bleed Procedure (Wet Modulator Assembly)” on page 14.


10. Repeat Steps 5 through 9 for the remaining 2 [sic] brake actuators.

NOTE: If a firm brake pedal resistance is felt and the brake pedal pushes back when the solenoids and pump are simultaneously actuated for each brake circuit, the system bleed procedure is complete. If there is no firm pedal resistance, repeat the bleed procedure and/or look into brake system defect, (leaks, etc.).



At the top of these instruction it says, The inlet solenoid valve should be open (de-energized).
So this is what I did. On Nanocom I pressed the brake pedal. I then selected "Inlet Valve OFF"(for the wheel I was doing). Nothing changed. I then selected "Outlet Valve On"The pedal then sank to the floor(Not sure if it went all the way but it did sink)


http://img825.imageshack.us/img825/3180/nanocomabs.jpg (http://imageshack.us/photo/my-images/825/nanocomabs.jpg/)

I then went to the next page on Nanocom and selected "ABS Pump Relay"
The pump started and the pedal kicked back at my foot pretty hard. I ran pump for about 5 pulsations and repeated the process 3 times.

http://img715.imageshack.us/img715/3180/nanocomabs.jpg (http://imageshack.us/photo/my-images/715/nanocomabs.jpg/)

Do you think I have done this correctly?

When I finished the above I then went and bled the wheels but I got no more air. As I said earlier, my pedal is good and brakes work as well as they did before.

[SiddersC]

Did you use the power bleed function in the Nanocom SLABS utility?

Or something different?

http://web.nanocom.it/download/WABCO%20SLABS.pdf

[OffTrack]

I read the instructions as saying that you keep the ignition off while doing the manual bleed portion to ensure the solenoids are de-energised. I don't believe it is necessary to do this via Nanocom.

The functions you need are in SLABS > utility > ABS bleed test

The abs modulator bleed is the equivalent of the pulse function mentioned in step 6. There is a test function for each wheel that the Nanocom docs say is for making sure the brakes grab when it's run. I think this can be used to pulse the solenoids for individual wheels.

The abs pump is run by "power bleed". It's probably similar result to doing it via the relay test but provides a timed pump run.

Cheers
Paul

[d2dave]

Did you use the power bleed function in the Nanocom SLABS utility?

Or something different?

http://web.nanocom.it/download/WABCO%20SLABS.pdf


Where in Nanocom do I find this? I just went and had a look and could not find it.

[SiddersC]

SLABS - UTILITY

[OffTrack]

It's on the second screen in the slabs module. There is a scroll bar at the bottom of the first screen, you need to click the right arrow.

[d2dave]

I found it, and no I did not do this when I bled brakes.

http://img832.imageshack.us/img832/3756/img8502x.jpg (http://imageshack.us/photo/my-images/832/img8502x.jpg/)

Can anyone explain what these features do.

I pressed "POWER BLEED" and the pump did one pulse. I then pressed "MODULATOR BLEED" and the pump did about 10 pulses. I then pressed "FRONT RIGHT TEST" and again it ran the pump for about 10 pulses. What is it testing?

I have been driving for about a week now. The brakes are fine and after doing the above made no difference.

[OffTrack]

Can anyone explain what these features do.

I pressed "POWER BLEED" and the pump did one pulse. I then pressed "MODULATOR BLEED" and the pump did about 10 pulses. I then pressed "FRONT RIGHT TEST" and again it ran the pump for about 10 pulses. What is it testing?

I have been driving for about a week now. The brakes are fine and after doing the above made no difference.

Nanocom Bleed Functions - YouTube

"Power Bleed" runs the abs return pump for a couple of seconds.
"Modulator Bleed" pulses the modulator solenoids and return pump for about 5 seconds.

Both these functions are reverse engineered versions of the routines that the Testbook system provides for bleeding the D2 ABS.

Running them on their own will make no difference to brake feel.


3. Connect diagnostic equipment to OBDII port.

4. Turn ignition switch ON

5. Push on brake pedal with maximum force (firm
pedal) and hold.

6. Activate the "Modulator Bleed" function on the diagnostic tool
starting with Passenger Front. (Note: you may be able to use the "test" function for each wheel for this step)

7. Release brake pedal for 5 seconds and run the Power Bleed function
for approximately 5 seconds.

8. Repeat Steps 5 through 7 three additional
times.

9. Perform manual bleed on appropriate wheels.

NOTE: To perform a manual bleed, follow
Steps 2 through 8 under “Manual Bleed
Procedure (Wet Modulator Assembly)”
10. Repeat Steps 5 through 9 for the remaining 3
brake actuators, working in order of Drivers Front, Passenger Rear, Drivers Rear.
NOTE: If a firm brake pedal resistance is felt and
the brake pedal pushes back when the solenoids
and pump are simultaneously actuated for each
brake circuit, the system bleed procedure is
complete. If there is no firm pedal resistance,
repeat the bleed procedure and/or look into brake
system defect, (leaks, etc.).


The repeated modulator/power bleed cycles followed by manual bleed ensures that any air trapped in the ABS Modulator and braking system is forced to the calipers where it can be bled out.


FRONT RIGHT TEST - FRONT LEFT TEST - REAR RIGHT TEST - REAR LEFT TEST
This function activates the modulation of the brake on the desired wheel. During the function if you turn the wheel by hand, you can see that it is blocked several times for few seconds.

I'd hazard a guess that you could use this to bleed or test pedal feel on individual circuits, not just by spinning the wheel.

cheers
Paul

[torxmaster]

Hey all,

I just changed brake lines all around, new pads and 2 new calipers in the rear on my Discovery 2 2003 TD5. I cleaned everything and drained the front calipers from brake oil. Now I had the perfect opportunity to use the "power bleed" function on my Nanocom.

I did it in the order RAVE suggest (shortest line first) ie. the opposite to "normal" brake bleeding. There are different suggestions here ont the forums but I guess RAVE must have some thoughts in its procedure.

Opened caliper front left (Its a left hand car), put a hose from the bleed screw to a bottle and turned on the power bleed.. Again, again and again. After 15 times fluid started to pour. I actually pressed the pedal a few times in between. When no bubbles, next wheel FR. The fluid came after 2 or 3 runs. It had a lot of bubbles. I pressed the button about 10 times more and moved to RL. This was a new caliper but the fluid came pretty quick and almost no bubbles. Then RR and that also went quick and almost no bubbles. I pressed the brake pedal a few times in between.

Then I did the modulator bleed 2 times with the pedal pressed hard. I did not let the modulator get any air during the brake change but you never know. I bled the system all around one more time. The bubbles were mostly from the front (right side?) and almost nothing from the rear.

The brakes are good now but the pedal is not super hard when running the car. Should it be? Its stone hard when the car is off. The automatic brakes works in low range.

I used about 1L of fluid in total. Maybe I should have drained more?

Just a thought, because of all the bubbles from the front, could that be the reason why RAVE suggest that you should start with the shortest line first? To get out the bubbles as much as possible so it wont wander to the rear?

I topped of the brake oil after 4-5 power bleeds the whole time.

Take care,
Carl

[d2dave]

The pedal will always be hard when the engine is off as there is no vacuum assistance. If there is air in the system the pedal will not be hard. It should not be super hard with engine running.

If the booster is working as it appears to be, the peal will always have a bit of a spongy feel, especially when comparing to engine off pedal.

When I did mine I just judged the pedal on it being the same as it was before I started working on it.

If HD and TC all work and it stops well without pedal going too far down, I would say that all is good.

[torxmaster]

The pedal will always be hard when the engine is off as there is no vacuum assistance. If there is air in the system the pedal will not be hard. It should not be super hard with engine running.

If the booster is working as it appears to be, the peal will always have a bit of a spongy feel, especially when comparing to engine off pedal.

When I did mine I just judged the pedal on it being the same as it was before I started working on it.

If HD and TC all work and it stops well without pedal going too far down, I would say that all is good.

Thanks! I will go out for a drive tomorrow and do some more testing..

/Carl

[ballbag]

Yeah, if pedal sinks with engine start your booster is working. These vehicles just have crappy pedal feel, sadly.

[d2dave]

These vehicles just have crappy pedal feel, sadly.

Disagree with that. My pedal feels similar to most cars.

[ballbag]

Probably should qualify my statement - good to me is rock-hard. Disco 2 pedal is at the softer end of the scale. The brakes work fine but compared to say, my WRX or my sportsbike, the pedal feels like putty.

[torxmaster]

I will do 3 modulator bleeds and power bleed 1L more just to test. I need to replace the CAT cable to the Nanocom because the plastic "spring" broke. Im going to replace it with a 5m cable. That way I can sit by each wheel.