G'day From Australia!

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xmexclusive
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Re: G'day From Australia!

Post by xmexclusive » Mon Dec 31, 2018 12:03 pm

Hi Jason

20 metres and light on seems very quick!
The Bendix ABS ECU does not cut in until the car reaches 5mph.
At that point it starts recording faults, it counts them down from 40 and does not put the light up or switch out until the count is zero.

The wires you are going to repair are "Twisted Pair" so try to maintain the wires like that.
The signals carried are very small and the twisting stops the wires picking up noise (unwanted signals produced when parallel wires act as aerials).

John

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Re: G'day From Australia!

Post by motorgnome » Mon Dec 31, 2018 3:33 pm

Oh no... It's a 001 part number!
IMG_20181231_163142-604x453.jpg
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Re: G'day From Australia!

Post by citroenxm » Mon Dec 31, 2018 4:32 pm

Something else for your order Jason..?
1990 H reg V6 24v Manual .. in progress.. on SORN
Projects:
92 Bx Txd Turbo
92 L Xm 2.1t D auto project
Others
55 C5 V6 24v Auto toy
54 Xsara picasso 2.0 8v Hdi
Shit thats scarey.. Two XMs left...

motorgnome
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Orga / RP numbers: Meteor Grey RP5058
Silver spares car RP4957

Re: G'day From Australia!

Post by motorgnome » Tue Jan 01, 2019 12:25 am

Ahhhh Paul!..Youre a funny man!..Actually the first person I thought of when I saw the ECU was a 001!!!
Stick it in with the steering wheel controls please sir!

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Re: G'day From Australia!

Post by xmexclusive » Tue Jan 01, 2019 2:07 pm

Light Sequence for XM Bendix ABS.
This information is taken from the UK MOT testers check sheet.
Switch ignition on, lamp illuminates then goes out after approximately 3 seconds.
Start engine, lamp illuminates then goes out approximately 3 seconds after the engine starts.
The document then lists XM's by model and age indicating if ABS is optional or standard fitment.

For the Bendix system there are two complete light on/off sequences.
All these indications are part of the start up static tests which repeat the same series of tests twice.
If you look very closely during the light on sequences 3 faint light blinks can be seen during each sequence.
These indicate completion of individual segments of each of the test sequences.
Individual check items are: ECU self test; ABS relay check; Wheel sensor resistance check; Valve block coil resistance check.

If you are checking out a XM Bendix ABS installation it is best to wait a minute or two and check the ABS light is off before moving the car.
Light on at this stage is the result of static test failure.

No wheel sensor outputs have been used up to this point and the extra work of waveform checking is wasted effort.
The static test fault(s) will remain and need clearing to move on logically.

John

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Re: G'day From Australia!

Post by citroenxm » Tue Jan 01, 2019 2:17 pm

I've a good one on my Xm 24v. Static test.. Light goes out.. However on moving pressing the brake makes the light come on releasing the brake makes it go out.. Then other times can be perfectly fine.. I'll get to it eventually. There's plenty of bits here for me to swap out.
1990 H reg V6 24v Manual .. in progress.. on SORN
Projects:
92 Bx Txd Turbo
92 L Xm 2.1t D auto project
Others
55 C5 V6 24v Auto toy
54 Xsara picasso 2.0 8v Hdi
Shit thats scarey.. Two XMs left...

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Re: G'day From Australia!

Post by xmexclusive » Wed Jan 02, 2019 11:51 am

Hi Paul

Bendix ECU monitors hydraulic brake pressure at the valve block to know when the brake is being applied.
This changes the ECU moving vehicle working programme from running mode to braking mode.
You do not mention the vehicle speed for the light to come on.
5 mph is the critical speed.
Valve block may be clogged with dirty hydraulic fluid so flush well using the two bleed screws.
ECU may be defective, rare but I would expect Lexia to show code 55, swap with a known good fault cleared one.
Finally a bit more drastic to do Valve block pressure sensor may be defective so replace whole unit with a known good one.

John

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Re: G'day From Australia!

Post by citroenxm » Wed Jan 02, 2019 6:51 pm

Cheers John. I'll get to sorting it when I start sorting her out fully..
1990 H reg V6 24v Manual .. in progress.. on SORN
Projects:
92 Bx Txd Turbo
92 L Xm 2.1t D auto project
Others
55 C5 V6 24v Auto toy
54 Xsara picasso 2.0 8v Hdi
Shit thats scarey.. Two XMs left...

motorgnome
Knows how to use the parking brake
Posts: 117
Joined: Sun Aug 26, 2018 12:36 pm
Orga / RP numbers: Meteor Grey RP5058
Silver spares car RP4957

Re: G'day From Australia!

Post by motorgnome » Thu Jan 03, 2019 10:35 am

ABS is GO!!
As the title implies, I have ABS operation with no fault codes..Woooo Hooo!
I removed the section of trapped wheel sensor harness, cut & repaired the broken section, carefully making sure not to disrupt too much of the twisted pair wiring, taped it all back up with TESA cloth tape & fitted it all back up.

With the rear sensors,(remember they had only a very small signal output), that was simply a matter of moving them closer to the toothed wheel. Even better, they weren't siezed in position. It was simply a matter of loosening off the 7mm lock bolt & moving them in till I could feel them hitting the toothed wheel (I had the road wheel off & the disc pads pushed back to give me good feel), then I moved them back out a "bees dick" & locked them up there. I then placed a mechanics stethoscope (has a metal probe instead of a cup) against the sensor & rotated the hub to make sure there was no contact. The scope revealed a much stronger pattern with voltages as high as 1.05 volts being produced by spinning the hub.

I cleared the codes, started it up, the lights went out & never came on again. I went for a 30 klm drive & apon return, checked again for fault codes & there were none. Great! So that's that for now..Lets hope it all behaves itself ..Time will tell.

So, I move on to the Hydractive. As I posted earlier, I have installed an LED tell tale so I can monitor electrovalve operation, as I wasn't happy with the ride quality. Well I can see it switch, but it's pretty random (to me) & it spends more time in hard than soft. I can make it switch with the steering, accelerator & brake, but I can be cruising along a flat, straight road at 70kph (40mph), light throttle, just ticking along & it'll be in hard mode..Half way through a corner it'll switch to soft. Something is wrong. I checked for fault codes & have code 25, which I believe is the Body sensor.

I haven't done anything else with it since pulling the code out of it, as I ran out of time, but tomroow, I'll clear it & go for a run to see if it comes back.

Meanwhile I have found a 78 page Citroen "Technical Training, Consultant Technician MODULE B7" document online, deatailing all the inns & out's of Hydractive I & II.

I live for this stuff!

I'll be back!

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Re: G'day From Australia!

Post by White Exec » Thu Jan 03, 2019 10:53 am

Good news on the ABS!

Does sound like body movement sensor misbehaving (or connections to it).
The B7 Module training document is really helpful in understanding how the components work, and carrying out electrical checks.
As you have Hydractive 1, there is only one EV (at the front) controlling both hydraulicc suspension regulators (centre spheres), so just one LED to fit.

Action of acc.pedal, brake and steering are all readily monitored with the LED. Body movement sensor less easy to deliberately trigger, unless you take a ridge or bump intentionally fast.

Check that the system isn't accidentally switched into Firm (Sport) mode, which (on H1) will bring on and maintain a lot of firm riding. Circuit diag will show which suspension ECU connection to check.

All this is good for the grey matter, yours and ours!
Chris
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