Abs Sensors

[DerekW]

It's me again with another simple question.

My 2.0 turbo estate has a Teves ABS system. I've read up the search results on ABS and find conflicting advice as follows: The fault is probably caused by a corroded connection in the wheel arch; to check the sensors, disconnect the plug at the ECU and check for resistance in each sensor circuit (should be about 1000 ohms).

But why not check the resistance at the connector in the wheel arch? Must be easier than struggling to reach the ECU connector (which one,? Mine appears to have two connectors).

Except that I can't find any connectors in the wheelarch, this is the left hand wheel arch:



and this is the right hand:



In each case the sensor lead runs ahead of the leg and disappears through the arch liner at the front. Can someone point me to the connectors? There must be one, otherwise how could you replace a sensor without dismantling the ECU plug and doing a bit of soldering? The spares manual doesn't show any detail.

If I'm right and there isn't an easily accessible connector, how about cutting the cable, carrying out the resistance check and then splicing them back together?

As always, all contributions gratefully received.

Cheers,

Derek


This post has been edited by DerekW on August 11, 2007 07:39 pm

[Peter.N.]

HI derek

I am sure mine had connectors, I remember checking them, but I can't remember where they were - I am sure someone else will. I wouldnt cut them if I were you as I think its a coaxial cable and you would have difficulty making a waterproof joint. There is some data on here somewhere that tells you which sensors are connected to which pins, I think Xmexc will be able to tell you. I am sure he will read this sooner or later.

Peter.N.

[xmexclusive]

Hi Derek

The Teves ABS lead connector for the front wheels is in a different position to the Bendix. It is hidden in the cross channel that has the bolt for the front bumper end. You have to remove the wheel arch lining to get to it but that is far easier to get to than the ABS ECU which is down on the hydraulic block on the front subframe passenger side of the engine bay. Rear connectors are in the standard inaccessible position on top of the rear subframe.

Regards

XMexc

[xmexclusive]

Hi Again Derek

Just read your posting a bit more carefully. The 2 ECU's in your black box will be the Main (engine) ECU and the Suspension ECU. The Teves one is integrated with the hydraulic block in the bottom of the engine bay. Teves resistances are very different to the Bendix ones, not sure of the value as code reading is the easiest way to fault find the Teves because of the hassel of getting to the bits.
Is it an optical illusion or is there a wide unworn rusty strip on the outer edge of your front brake disc? If it is real then either the discs or the brake pads are not the right ones.

Regards

John

[DerekW]

Thank you Peter for the warning about cutting the cable - duly heeded.

Thank you John for the valuable info concerning the whereabouts of the connectors. I knew you'd come up with the goods.

I located the Teves ECU, but as I wrote, there seem to be two plugs connected to it. Academic now that I know where the connectors are.

There is the usual very narrow edge of rusty material at the rim of the front discs, the apparent wide rusty area is an optical illusion, it's the edge with the cast in cooling fins, or are they spacers?

Thanks once again,

Derek

[DerekW]

Hi xmexclusive and anyone else interested,

I was wrong (again). As you said there is only one plug going into the Teves ECU, with four looms - obviously the cables from the four sensors - going to it. I thought there were two side by side plugs.

The plug is reasonably getatable on the turbo, I can reach it with the left hand thumb and forefinger. Is it just a straight pull off or is there some fancy catch holding it?

Now I'm getting used to working on this car I think the old 8 valve engine is the easiest of the lot for maintenance.

You're right about the amount of metallic particles floating around the sensors, the way it sticks suggests it's magnetic. If I wave a small magnet around to collect it, will that upset the sensors?

Derek

This post has been edited by DerekW on August 12, 2007 03:21 pm

[xmexclusive]

Hi Derek

The plug looks identical to the one on a Bendix ECU. Lift up latch at centre top that pulls up towards the passenger side chassis then there is a lug on the other end (cable exit) of the plug that is hooked into a little metal goal post fixed on the top of the ECU. The Teves sensor is fully sheathed in a metal case so cleaning it should be easy as there is nothing exposed to damage. My gut reaction is that a magnet will not harm the sensors BUT replacements are very expensive and I would hate to encourage an action that ends up with you having to buy four new ones.

Just to put the information on record according to my manual the original Teves ABS was fitted from ORG 6749 to ORG 8028. From ORG 8028 a TEVES MK20 ABS was fitted with no indication of finish ORG.

For the original Teves connector pinning is: Front Nearside pins 15 & 30, Front Offside pins 1 & 6, Rear Nearside pins 28 & 19, Rear Offside pins 29 & 31. Pins 11 & 24 should be EARTH. The 12 volt supplies are: Main Supply through ABS Relay (844) from fuse F3 goes on to pins 13, 25 & 37 supply energised with ignition key in middle two positions (A&M) only. This relay is energised with a supply from the ignition switch via fuse F1 that also goes to pin 33 of the ABS ECU. There is also a supply to the ECU pin 22 that comes via the ignition switch last two positions (M&D) through fuse F19 then via the NORMALLY OPEN stop lamp switch to the ECU. The diagnostic socket contact E1 is fed by pin 27 of the Teves ECU.

Regards

XMexc

This post has been edited by xmexclusive on August 12, 2007 09:07 pm

[DerekW]

Thank you once again XMexc, that's a pretty comprehensive reply.

Derek

[jorgy9]

Hi John,

would you be able to report the normal resistance specs for the sensors of an ABS on a PR6336 car (some version of Bendix then?).

Thanks very much
George

[jorgy9]

hmmmm, so, is the info below right for the Bendix ABS ecu?


" The ABS / Hydractive ECU has two plugs on it, one white and one black - disconnect the black one for this test. According to my 'Revue Technique' manual the corresponding terminals (sensor locations) in the plug are (for a Mk1 XM): 2 and 35 (nearside front), 18 and 32 (nearside rear), 17 and 34 (offside rear), 16 and 33 (offside front). The terminal numbers are moulded (faintly!) into the plastic of the plug). For wiring and a sensor in good condition a resistance of 1000 to 1400 ohms is normal. "



cheers
G

[jorgy9]

...and I also read elsewhere that the Bendix ecu in black box has 1 multiplug only? So do the pin-checks mentioned before apply? (Don't have the car with me to go and check).

G

[xmexclusive]

Hi Derek

It just happened that a bit of Teves information was in some workshop manual odds and ends I got recently on ebay.

Hi George

All I can lay my hands on at the moment for Bendix ABS is the RTA manual which I think (it may be best if someone who understands French checks this) gives:
ABS Capteur resistance should be between 1.0 and 1.4k ohms.
ECU pinning:
Front left pins 18 & 35
Front right pins 16 & 33
Rear left pins 15 & 32
Rear right pins 17 & 34
It also says that if you get someone to spin a jacked up wheel you should be able to measure between 50 & 2000 mVolts output from the sensor on the contact wires.

The comment about the Bendix ABS ECU having 2 plugs is wrong (it is the suspension ECU that has 2 plugs) though I think that all the rest of the information given in that post is correct. The XM Mk1 Bendix ABS used at least two different ABS ECU's over time. Of the two I have in the store both are black rather than silver cased and the only difference seems to be the part number. It is because of this ECU difference that I cannot be certain that the early system used the same ABS sensor wire numbers. I think that the early Mk2's used the same Bendix system as the later Mk1's but again do not know if Citroen changed the part numbers for the Mk2's. My interest was only in using late Mk1 sensors in an early Mk2 car and this worked ok.

Regards

XMexc

This post has been edited by xmexclusive on August 14, 2007 03:30 pm

[jorgy9]

....another version for pins combinations on the Bendix ecu:

" The first pair is terminals 35 and 18 and these are for the front left wheel
The second pair is terminals 34 and 17 and these are for the rear right wheel
The third pair is terminals 33 and 16 and these are for the front right wheel
The first pair is terminals 32 and 15 and these are for the rear left wheel "


and another one:

" Later on if all else fails you can check the resistance of each of the ABS sensors from this plug (pin pairs are usually 15/32 16/33 17/34 18/35). "


...and a resistance spec:

" A measurement taken across each pair should read approx 2000ohms. "


So anybody can confirm the correct pin combinations?
And the normal resistance (have read 1000, 1100, 2000)?

thanks

George

[jorgy9]

Thanks John,

-was typing and searching simultanelously!-, I ll take those as the correct values then. I better inform my indy asap -could help him sort out my MOT-failed XM-.

regards
G

[xmexclusive]

Hi George and All

I think we both may be right about the pinning it is just that there are 2 versions of the Mk1 Bendix ABS (early & late) and they do not use the same ecu, wiring loom or pinning.
On the actual measurement of resistances it is important to know the accuracy of the meter being used as many of the cheap meters may or may not be that accurate. If I was going to check ABS sensors I would check a few known value resistors in the range 100 to 10,000 ohms just to be sure of measurement accuracy.

Regards

XMexc