ABS fault light not clearing on Xantia Mk1

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xantom
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ABS fault light not clearing on Xantia Mk1

Post by xantom »

I've had the ABS fault light in my Xantia 1.9TD Mk1 for a long time now but the MOT's due now so I've had to get off my backside and sort it. Turns out that when I did a resistance check on the pins in the ABS connector I was getting no circuit at all from the Front OS and the Rear NS. The front OS was easy; I'd disconnected the cable early in the year for some welding nearby and forgotten to reconnect it. That reads 1100 now. The Rear NS was just dead so I replaced it, and that was a very awkward task but completed so I have 1100 reading on its pins too. Everything is good going into the ABS box now but the light hasn't cleared. My question, guys and galls, is should it clear when the fault goes or must it be cleared with a Lexia input? I have a Lexia but not the big brown connection needed for my Mk1 Xantia. Any solutions out there?
Thanks
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Re: ABS fault light not clearing on Xantia Mk1

Post by Hell Razor5543 »

Have you driven her since changing the sensor? If not, all you need to do is to take her for a drive. Once the ABS ECU sees that all sensors are working properly (seeing the wheels rotating) it will come back on-line and put out the error light.
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white exec
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Re: ABS fault light not clearing on Xantia Mk1

Post by white exec »

Not sure about Xantia, but on XM there is an ABS relay (standard-looking cube relay, green, but with extra small connector pin) that controls the ABS light. If this malfunctions, the light can remain on or behave erratically. Check out the circuit diag.
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Re: ABS fault light not clearing on Xantia Mk1

Post by xantia_v6 »

There were a couple of changes to the Xantia ABS throughout production. I think that the car in question probably has Teves Mk4, but I am not sure. This system does not have a separate ABS relay (it is embedded in the ABS valve block).

If the fault does not clear after a short drive, it will be necessary to connect the car to a Lexia to get the fault codes for diagnosis. Note that it will require a Lexia with a 30 pin adapter.

Early Xantia ABS ECUs often failed due to internal corrosion, but I think that this car was produced after that problem was addressed.
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white exec
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Re: ABS fault light not clearing on Xantia Mk1

Post by white exec »

Xantom, if you can post your VIN, we can check out which ABS system you have, and look out its circuit details. Thanks.
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Re: ABS fault light not clearing on Xantia Mk1

Post by xantom »

Thanks guys. I have re-confirmed the good signal from all 4 sensors to the plug but a test drive with some brisk braking still hasn't cleared the fault and I can confirmn the ABS isn't kicking in. The car's VIN is VF7**************[VIN obfuscated, can be read by forum staff]. Hoping to MOT her on Monday, having guilty thoughts of disabling the bulb and hoping they don't notice. Just thoughts, officer.
Tom
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Re: ABS fault light not clearing on Xantia Mk1

Post by GiveMeABreak »

The RPO of this Xantia is 07015. All I can see about mods for the 1996 range from RPO 6748 to 7113 concerning the ABS is:
Replacing of ECU MOTOROLA by ECU ALCATEL.
The functioning of the 2 ECUs is extremely identical.
Interchangeability: The new parts are fitted in place of the old parts.

The ABS unit fitted is:
Xantia ABS.PNG
Part 4 was the Relay Mike was mentioning, part number 96131693.
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white exec
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Re: ABS fault light not clearing on Xantia Mk1

Post by white exec »

Thanks for posting the VIN, which makes your RPO no.7015 (= mfg date of 23Jan1996).
The circuit diags I have (for XM, same system) suggest brake system is Teves 4, which includes that small separate relay (#4 in the Marc's diag above).

Function of the relay is to control the ABS dash warning light, including extinguising it, when the relay gets a command from the ABS ECU. (edited correction)

If the contacts (internal or external) of the relay are dirty or not functioning, the dash light will not operate properly. Dirt/corrosion is a known problem for relay sockets mounted "up front", where they get weathered. Check the relay contacts too; its cover can be popped off to get to the internals.

The relay is a "special" (it contains an additional diode) with an extra small base pin (30a) for connection to the dash light, and is Cit pt no 96 131 693, but NFP. The relay case has the circuit diag moulded into it. They don't usually fail, but do respond to a clean-up.

The operation of the relay can be observed by leaving its cover off, and watching the contact action as the IGN is turned on.
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Re: ABS fault light not clearing on Xantia Mk1

Post by xantom »

Thanks again. The diagram is excellent and I've been out to check. For the life of me I can't locate a relay anywhere near the ABS unit. Does anyone know its specific location? Is it perhaps one of the relays in the engine fuse/relay box just in front of the ABS unit? I'm quite happy to move the LHM tank out of the way a bit if it's tucked under it.
Tom
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white exec
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Re: ABS fault light not clearing on Xantia Mk1

Post by white exec »

Marc,
If you have a component location diagram the ABS Relay is #844.
C.
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GiveMeABreak
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Re: ABS fault light not clearing on Xantia Mk1

Post by GiveMeABreak »

white exec wrote:
10 May 2019, 17:55
Function of the relay is to control the ABS dash warning light, including extinguising it, when the relay gets a command from the suspension ECU.

Do you mean ABS ECU Chris? No suspension ECU on these :-D Unless that's the Suspension Regulator Control ECU for soft / firm switching (this is a non-hydractive model), but can't see how this interfaces with the ABS ECU?

I have extremely limited Xantia Data Chris, but will have a squiz.
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Re: ABS fault light not clearing on Xantia Mk1

Post by xantia_v6 »

I only have 1 mk1 Xantia diagram, which may be the Teves mk4, or may be the earlier system. It shows that the relay is inside the ABS block and has no direct connections to any external wiring.

Note that on the Xantia (unlike the XM) the ABS block is mounted high in the engine bay, next to the LHM tank, and is not subject to road spray. They very rarely fail, other than the early ECUs which I think were phased out by 1995.

It is more likely that the fault here is due to a wrong ABS sensor fitted, or a problem with a reluctor ring.
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white exec
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Re: ABS fault light not clearing on Xantia Mk1

Post by white exec »

Marc,
Yes, ABS ECU, not suspension. Have corrected it. Oops.

Mike,
My wiring diags here all show Teves 4 having the external ABS relay.
The built-in relay shows as part of the later Teves mk20 system.
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Re: ABS fault light not clearing on Xantia Mk1

Post by GiveMeABreak »

The relay is part number 96131693, but I can't locate a UK based one - mostly in Europe:

https://www.google.co.uk/search?client= ... 8&oe=UTF-8
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white exec
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Re: ABS fault light not clearing on Xantia Mk1

Post by white exec »

Looks like a few about still, which is helpful.

Not too difficult to replace with a standard 5-pin (changeover) relay, and add the additional diode and connection. The circuitry for this is clearly displayed on the relay case, including the polarity for the diode.
Alternatively, test the original relay and its diode, and repair as needed.

My guess is that it is a Green one, usual 1" cube.