Gasa XM 2.1 "Prestige"

[Gasa]

Here I would like to present my XM 2.1 Turbo D, "Prestige", the model is from 1997, it has 214,000 km.
The car has not been driven for a long time, more than 10 years, the interior is quite well preserved, the only thing is that the paint has completely faded and will need painting. For now, I need to do a classic oil service, belts and everything else that goes with that service.
I noticed that the ABS doesn't work, only the front wheels are braking, I don't know if the problem is with the sensors or the rear calipers, I'll see what it's about these days...
So much for the first report for now, here are some pictures of XM.

(R)Fotografija0022.jpg

(R)Fotografija0025.jpg

2.jpg

IMG_20221218_132502 (2).jpg

IMG_20221219_123935.jpg

[Gasa]

...pictures and interiors

IMG_20221218_144711 (2).jpg

IMG_20221218_134351.jpg

IMG_20221218_134107 (2).jpg

IMG_20221218_140949 (2).jpg

[Dieselman]

How do you know the rear brakes are not functioning?
If the rear is lifting during braking that is likely to be air in the rear brakes, just bleed them.

The ABS and rear brake issues are seperate, what exactly happens with the ABS lamp at Ign on? It should come one, flicker twice, then extinguish.
If the lamp comes back on before the car moves then the issue is a wheel sensor having open circuit, the ABS relay not functioning, No power feed, or Ecu is duff.

Check the wheel sensors for connectivity and resistance and the relay function, as they are the most likely issues.
The rear ABS sensor connectors on top of the rear subframe are likely points of failure.

Details are in the circuit diagrams.

viewtopic.php?f=13&t=7592&start=110#p124757

Can you read the fault codes? Being a 1997 car it is at the change from Teves Mk4 to Teves Mk20. The earlier system outputs Blink Codes, the later one high speed data only.

[Gasa]

... checked today what the brakes are like, the front discs are braking, they leave a tire mark , the rear nothing , I have nothing to bleed the air from the rear brakes, I will take a look one of these days and do that.
Not a single light comes on to indicate that something is wrong, the only thing that shows this message on the display, that's why I think there is a problem with the ABS.

IMG_20221222_193652.jpg

The rear pistons are good, they didn't block from stopping, it's good that I also looked at the condition of the discs, I was hoping that this was also the reason why it didn't brake at the back, the discs were so buried that they came together and the pistons couldn't transfer the force to the disc. instead, they were leaning on each other, I sanded the tiles ,nothing, same situation.

IMG_20221222_122805.jpg

IMG_20221222_150848.jpg

...you can't see the disk, all the tiles are connected.

IMG_20221222_150604.jpg

IMG_20221222_124407.jpg

..now the plates have full contact with the disk.

IMG_20221222_124616.jpg

[Dieselman]

I understand the issue with the disks and pads now, the pads are overlapping the disks and so are not exerting any force due to being worn down and pressing against each other.

It looks like your car has the wrong disks fitted, they are too small, allowing the pads to run over the edge. They are probably Xantia, or Bx disks.
I have seen this issue on the front of an Xm. People do this to save a few pounds, but don't realise how dangerous it is. When the pads wear and press against each other, there is no braking.

By design the rear wheels will never lock under hard braking, to keep the rear of the car in line with the front, otherwise the car would spin round.

The ABS warning lamp should illuminate at Ign on. Someone has removed the bulb to hide the fault.
Fit a bulb, read the codes, fix the fault.

Wesacossa's video of his non-functioning ABS, which is an Ecu fault. The relay, or Ecu will give no blink at all.

[Gasa]

Thanks for the explanation, I'll see how to bleed the rear brakes one of these days.
I hardly understand the ABS system, I see that there are a lot of problems with that system on XM.
If I can't do the ABS, I end up having to take the whole system off and make it like a regular system on the BX.

[Dieselman]

Bleeding the brakes is really easy.
Start the engine, raise the car to the high setting, block the brake pedal down partially to apply the brakes, remove one wheel, fit pipe to bleed nipple, open bleed nipple to let fluid flow closing bleed nipple once clean, un-aerated fluid flows, replace wheel.
Repeat for each wheel in turn.

Fixing the ABS isn't difficult, you will need a DMM and a test lamp to diagnose it. We should be able to assist you.
The wheel sensors should have 2,200 Ohm resisance, the relay and Ecu need +12v and Gnd to function.

If you don't already have one, build a Blink Code Reader, to read fault codes on your car. It won't work on Teves Mk20 systems, but they can still be diagnosed using the Dmm and test lamp.

See thread for blink codes reader and information.
viewtopic.php?t=7368

[Gasa]

...later they will look at that ABS that has the problem, I don't know what model ABS is on this xm, where is its EKU, I looked at fuse no. 1 and it has
power.

IMG_20221222_122813.jpg

IMG_20221222_121059.jpg

...in the box there is an ECU for the engine and some relays, I don't know what they are for.

IMG_20221222_104545.jpg

[Dieselman]

The Ecu you show in the Ecu box is the engine control module for the Delphi Epic system
The larger, oblong relay is the Double relay for the engine controller.
The smaller relay is A/c cutoff.
I can't see a Hydractive Ecu in the box, is there one, or does this car not have Hydractive?

You appear to have the earlier Teves Mk4 Abs system, fitted until Rp 8029, so should be able to read codes with a Blink Code Reader.
The Ecu for this is mounted on the side of the valve block, the relay is mounted in front of the battery tray.

I'm confused about your rear brakes issue, the disks can't be from a Xantia or Bx, as they have a 5 bolt pattern, but either the disks are too small, or the pads too large (possibly for Estate with 251mm disks), or the pads are sliding out of the caliper due to not having the retaining pin holding them in position.
Your disks should be 224mm.

[Gasa]

It's not hydroactive, it's a regular system, if it was hydroactive, I wouldn't have taken it because it's complicated.
I will check for the size of the discs, I am currently finishing the replacement of the panel for the PK belt and overhaul of the alternator.
The panel with the amotizer has never been changed, it has lasted well for all these years, I have now replaced it all and completely overhauled the alternator.

IMG_20221224_111207.jpg

IMG_20221224_120657.jpg

IMG_20221224_120935.jpg

IMG_20221224_084054.jpg

IMG_20221224_111553.jpg