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Topic: ABS light on - failing rolling test (Read 4139 times) |
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ottopmh
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ABS light on - failing rolling test
« on: Mar 4th, 2011, 9:50am » |
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Hello!
I have some questions related to the unpleasant ABS light
Light goes off after first check, but illuminates after rolling test. Always. It started all at once and the fault was never intermittent. However, TCS controls the throttle after startup but of course dies away once the rolling test triggered by speed is carried out. But TCS does not operate brakes, only throttle - and after which the ABS light illuminates even though staying all the time below rolling test speed. This pretty clearly, to my opinion, shows that at least rear sensors and TCS are working.
Then some background: I've changed front discs, pads and right hand side hose over one month ago. Everything worked fine since then. Two weeks ago I changed rear discs, pads and right caliper. ABS light illuminated one day after repairing rear brakes and has not come off since.
Whilst bleeding - just in case if the system would contain air due to the recent repairs and to get fresh juices in - the system yesterday I noticed that when bleeding right hand side front caliper I could hear a "fffzzzzzz" from the ABS pump. So I assumed that there is air but at least so far I've not been able to get it out.
Does anyone know if a pump (or solenoid) can FAIL with symptoms described above? Further on can air cause rolling test fail as I did read that each solenoid is fired then?
The next step is perhaps to see if there is dirt in wheel sensors which I doubt as the light is constantly on.
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Mike H
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Renault Clio
 
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Re: ABS light on - failing rolling test
« Reply #1 on: Mar 4th, 2011, 4:45pm » |
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You say "after repairing rear brakes", you might have inadvertently damaged a rear ABS sensor or its wiring in the process (?)
I learned a trick a while ago re bleeding fluid, have someone or something hold a jar into which the bleed tube goes higher up than what you're trying to bleed, stops air bubbles going back in 
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Mike H
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PJDavis
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2 x 1995 Jag X300 3.2 / 4.0 (Henley) 1957 XK140
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Re: ABS light on - failing rolling test
« Reply #2 on: Mar 4th, 2011, 5:35pm » |
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Another way of ridding the system of air is to block the brakes down. A rather 'old-fashioned' way and takes 24 hours but still works.
You need a length of wood, that will go from the foot-pedal to the front of the seat whilst the brake is pressed. Now, you don't need to try and press the brake through the floor, you just need to have it firmly enough pressed to make sure the both systems in the master cylinder are open. First, press the brake pedal about 20 times slowly and firmly down and release to exhaust any servo pressure. On the last press have your piece of wood ready and block the pedal down. Leave for 24 hours. This ideally would be done after a short run, and when the brakes are not overly warm. Make sure the cap on the fluid tank is loose enough to allow air out. Like a lemonade bottle when the cap is open, all air should rise to the fluid-tank given time.
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1995 Jaguar XJ6 X300 3.2 (Henley)
1995 Jaguar XJ6 X330 4.0 (Dopey)
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gozz
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Re: ABS light on - failing rolling test
« Reply #3 on: Mar 4th, 2011, 10:26pm » |
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PJD.
That's a new un,how does the air return through a master cylinder under pedal pressure ? surely there is no route for it past the piston !
GOZZ.
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Snoopy
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Re: ABS light on - failing rolling test
« Reply #4 on: Mar 5th, 2011, 7:45am » |
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Could well be some debris from the discs lodged on the sensor ring after cleaning etc.
The way to bleed the brakes on the scorpio is to have the receiver bottle higher than the calliper. It was discovered some time ago by one of the members who could not rid the system of some air.
I agree with Gozz!!!!!!!!!!!!Holding the pressure on the brake pedal does not in my book do anything positive except keep pressure in the system.
If I can find the posts relating to the brake bleeding I will refer back to it.
Here it is its from JC some time ago
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ottopmh
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Re: ABS light on - failing rolling test
« Reply #5 on: Mar 5th, 2011, 7:58am » |
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I didn't want to argue, but I'm very suspicious that the air would be able to pass its way from ABS pump back to the reservoir, no matter how long the pedal would be pressed.
I have seen many instructions where a bottle containing fluid is to be placed high enough. Instead I've done it so that mate is applying brakes and then I've opened the bleeding nut and just before pedal reaches bottom I've closed the nut fluid still being purged out. It is a slow process, but no air is allowed back to the caliper.
To my opinion I was very gentle - as always - and no wiring should've been harmed. Dirt is one option as I had to, _very_lightly_ though, tap both rear discs with hammer before they came off. Supposedly the next step is to check sensors in case of excessive dirt and then finally order a specific OBD cable and read the ABS codes.
Umm... Could the "ffzzz" sound from ABS pump be due to sticking solenoid? Has anyone come across this kind of problem? This just came to my mind whilst previewing this post and reading "tap". Perhaps I should "tap" the pump with hammer a bit?
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Scorpabilly
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Re: ABS light on - failing rolling test
« Reply #6 on: Mar 5th, 2011, 8:01am » |
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Blocking the pedal with a length of wood is well known in the Zephyr/Zodiac world particularly with Mk 1s. The reasoning is that there is a reciprocating seal which doesn't "pop" out and fluid just goes in and out of the reservoir. Also with some of the newer harder rubbers the cup seals don't flare out as they should and holding pressure for a day helps this.
Bob
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Tompion
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1997 2.3 Ultima estate.
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Re: ABS light on - failing rolling test
« Reply #7 on: Mar 5th, 2011, 11:56pm » |
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With a non TCS I have driven my car with the ABS plugged in but not attached to the valve block & it passed the rolling test, so air in the system/faulty valve has no effect.
I would imagine the same applies to a TCS system, but I’ve not tried.
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ABS multiplug wheel sensor pins MK IV or MK 20
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ottopmh
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Re: ABS light on - failing rolling test
« Reply #8 on: Mar 7th, 2011, 4:29pm » |
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Today I got one possible problem eliminated. ABS pump is working and operates brakes as it should. This happened by unintentionally at office's garage where at roof level the driveways are quite steep and today the thick ice formed during the winter had also a wet dressing on top. So it was very very very slippery. This made it possible to test if ABS works even without actually trying to do so. And without exceeding the rolling test speed beforehand.
Since that I had a quick look at the front sensors by removing the plastic wheel hub covers (I hope that this is what they are called) and there was no debris. So, next it is time to check rear sensors. I can see that this will end on ordering OBD lead
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ottopmh
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Re: ABS light on - failing rolling test
« Reply #9 on: Mar 9th, 2011, 9:19am » |
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This morning I had yet another chance to test ABS before exceeding the self test speed. ABS worked again but now I pressed the pedal more heavily and I could sense that the pedal went soft as ABS operated. I mean, it felt exactly how it feels when there's air in the system or cylinder would have a leak. However on normal brakings the feel of the pedal is as firm as it should. And in addition I think that the noise generated by ABS operation was slightly different.
So I'm referring to my original theory - air in ABS pump.
I had a look at discussions in other sites as well and I learned that Teves ABS (both IV and 20) should be bleeded by running a bleeding sequence using a scan tool (air in master cylinder or ABS unit). Steps would be 1. normal caliper bleeding; 2. bleeding sequence by scan tool; 3. again normal caliper bleeding.
I can't remember never reading this kind of stuff on this site. Can anyone tell whether that is true or not for a Scorpio?
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Tompion
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1997 2.3 Ultima estate.
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Re: ABS light on - failing rolling test
« Reply #10 on: Mar 9th, 2011, 10:34am » |
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I doubt bleeding will have any effect with regard the light coming on.
It certainly doesn’t with non TC systems.
In the past I’ve had the ABS cut in at walking speed when no wheels were about to lock, usually causing the light to come on, - it felt like the car wasn’t going to stop.
In one case it was due to too big an air gap on a rear sensor (the sensor was worn due to coming into contact with the sensor ring caused by a failing wheel bearing).
In the other case it was the early stages of a failing controller.
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ABS multiplug wheel sensor pins MK IV or MK 20
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ottopmh
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Re: ABS light on - failing rolling test
« Reply #11 on: Mar 9th, 2011, 11:07am » |
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Thanks for the response. I'm testing my theories (in theory...) while waiting for suitable time to have a look at the rear sensors.
Just in case and to be more clear: this morning I did test ABS on purpose over ice. So it was supposed to kick in and what I noticed was that the feel on the pedal was slightly different. And of course - after that the light went on.
BTW - mine has TC, how does it change the situation when it comes to bleeding?
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Tompion
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1997 2.3 Ultima estate.
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Re: ABS light on - failing rolling test
« Reply #12 on: Mar 9th, 2011, 2:00pm » |
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If there were air in the valve block I would expect the pedal to feel spongy whether or not the ABS kicks in.
I’m not aware of any special procedure for bleeding a TC system.
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ABS multiplug wheel sensor pins MK IV or MK 20
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ottopmh
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Re: ABS light on - failing rolling test
« Reply #13 on: May 11th, 2011, 2:20pm » |
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I gave up and ordered a cable from Mr Alex.
I have C1095 ABS Hydraulic Pump Motor Circuit Failure. So it seems that I'm off to dismantle the controller and hoping to find bad solderings.
Are there any other more or less common causes for this trouble code?
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Tompion
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1997 2.3 Ultima estate.
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Re: ABS light on - failing rolling test
« Reply #15 on: May 11th, 2011, 2:46pm » |
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A faulty controller seems to be the most common cause of a 1095 code.
One of the ABS fuses will produce this as will faulty wiring to the ABS plug. You can test for voltage at the multiplug, you can also test the motor at the same time by connecting it directly to the relevant pins in the multiplug. These wires (one of the thick pairs in the multiplug) are permanently live so take care.
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ABS multiplug wheel sensor pins MK IV or MK 20
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ottopmh
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Re: ABS light on - failing rolling test
« Reply #17 on: May 12th, 2011, 10:28am » |
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Thanks for the link pointing to older discussion. I think that I've seen it before but did not read it carefully back then. Bad solderings really seem to be a common fault.
I will start from the easiest 1) fuses (done already) - 2) measure multiplug wiring - 3) test pump with direct connectiong from battery and 4) have a look inside the controller box.
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Tekno
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Tenho Ruohoranta
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Re: ABS light on - failing rolling test
« Reply #18 on: May 14th, 2011, 11:10am » |
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pump can still work at <15km/h even though soldering points are gone bad. but if there is resistance enough it generates "error" on bout 10-15km/h and stops working. My abs did work in very very low speed, when fault light was not illuminated yet. also when accelerating on ice, TCS worked to the point where driver lifts foot from gas pedal or tires get first traction (then fault light comes and no abs/tcs anymore)
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1998 Ford Scorpio Ultima Estate 2.3i 16V
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ottopmh
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Re: ABS light on - failing rolling test
« Reply #19 on: May 16th, 2011, 1:57pm » |
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OK, my experiences are identical to Tekno's post above. As I've already written both ABS and TCS do work until passing 15 mph or until either one of those is being operated.
I'll let you know what I found once I've opened the box and checked it out.
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