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        General >> Problems >> ABS Not working *HELP*
        
(Message started by: pappa on Jan 9^th, 2008, 9:35am)

Title: ABS Not working *HELP*
Post by pappa on Jan 9^th, 2008, 9:35am

Howdy!

I've been struggling with an ABS related problem and slowly
getting a bit nervous about it. The MOT is due in a few days.
;)

The history is this:
* Did a HUGE heart transplant operation (from a wobbling
24V to a brandnew 2.3 DOHC)
* The full wiring loom was changed, the old one was for 24V
and had TCS in it.
* Re-connected all the leads in the ABS controller that were possible to re-connect
(TCS related leads obviously left hanging about, because
the new loom did not have TCS in it )
* The ABS worked for sometime
* Problems started appearing, ABS light on and ABS worked with a delay. Pressing the brake caused lock breaking first and then ABS kicked in/Light off, then after a few secs it turned off and locked breaking continued.
* ABS stopped working alltogether, light on all the time

Done the following:
* Changed the ABS unit from a working car, did not help.
* Gone through the wiring with a wiring diagram, checked
that power comes into the right places. One lead still is a suspect, it did not have power even when the engine was running. It comes from the main fusebox, from the fuse F27, which I have checked has power when the power is on. It comes to the connection point 15 of the ABS controller. This is prime suspect, because it seem to be a direct wire from the fusebox.
* cleaned all the back sencors (boy they were covered in dirt)
* swapped front sencors from a working car (one of them is new)
* Cleaned also all the multiplugs on the sencors
* checked ground leads of the ABS controller

So pretty much have been done already, anyone had this sort of trouble before - ABS turning on with a delay and then stops working, finally ending up not working at all?

Title: Re: ABS Not working
Post by Tompion on Jan 9^th, 2008, 10:52am

Which version of ABS

Could it be a dodgy brake light switch? - maybe run a bulb from the brake lights so you can see if there's a problem coinciding with the delay.

Title: Re: ABS Not working
Post by pappa on Jan 9^th, 2008, 11:08am

Which version of ABS? Er... I don't know. The one that is in there now is
from a -97 Cossie. The ABS controller + the whole lot.

That's a good idea, the electric connection from the brake pedal to the
ABS controller. I reckon my brakelights are working ok.

And the ABS is currently not working at all. It "faded" away. Started
with the delayed action, then the delayed action weakened and
finally no ABS. After that I re-newed the ABS controller (the whole
system).

Thanks!

Title: Re: ABS Not working
Post by Tompion on Jan 9^th, 2008, 11:15am

Have you tried running a seperate fused wire from 15 direct to the battery

Title: Re: ABS Not working
Post by pappa on Jan 9^th, 2008, 11:28am

Not yet (haven't had the time) but that's the next step to do.

Just fishing out if anyone has come across the same phenomenan
before.

I have a FORD T.I.S. CD in my laptop, but I don't seem to find
a description for the pin 15 of the ABS controller.

The stoplamp switch comes to pin 20, if my eyes are not that
crossed.

Title: Re: ABS Not working
Post by Tompion on Jan 9^th, 2008, 12:08pm

Pin numbers vary depending on whether MKIV or Teves20

3 ABS diagrams here:
http://www.carsoft.ru/avtorepair/sierra_el.html

I have a connector plug in front of me for the teves 20 no wire to pin 15

The teves 20 is a more compact unit the valve block is machined out of a flat billet of aluminium (no bulges like the other unit) The main plug is easily accessed (I believe it's underneath on the other unit)

Title: Re: ABS Not working
Post by TiberiuS on Jan 9^th, 2008, 4:45pm

Hi. There's a common fault with some of the Teves units from that era (like the one I had in my 2.3), the circuit board inside the ECU unit flexes and the conductive traces gradually crack, leading to intermittent faults all over the ABS system (I've been here). If the wheel sensors test ok and the wiring's ok then start suspecting the ECU, you can get them repaired for about £120 here in the UK at least. You can spin the wheels off the ground and check the sensor inputs with a scope at the main multiplug on the ABS body.

Is the TC in the Scorp linked to the rear brakes or just the throttle body? On the models where TC incorporates the rear brakes, the ABS pump unit has more solenoids so might cause issues in a non-TC car.

EDIT: Also check the plug which feeds the motor in the pump unit, if the motor doesn't spin, you'll get warning lamps and no ABS.

Hope this helps some.

Regards, Bruce.

Title: Re: ABS Not working
Post by pappa on Jan 9^th, 2008, 7:17pm

Thanks Bruce!

Hints taken, saturday is reserved for this project. Thumbs up!

Title: Re: ABS Not working
Post by pappa on Jan 12^th, 2008, 12:32pm

Hi all.

Thanks for participating into this project. It's not sorted
yet, but I think it is the RENEWED ABS sensor that is
giving me trouble.

I sorted all the above, stop lamp lead has power when
pedal pressed, got power to the mysterious non powered
lead as well (brake pedal & this one were crossed, they
are the same color ??? ).

Then measured the resistance in the sensors and all other
sensors gave 1.03k ohm except the RENEWED one which
gave 18.07k ohm !

Also tested the front sensors with rolling wheels and
measured some power fluctuations (don't have an oscilloscope).

But the resistance of the renewed sensor has a significant
difference if compared with the other one. Has anyone
got an idea how much the resistance should be? If I
remember correctly, it should be aroubd 1.00k ohm.

Ok, that theory went down the toilet. I tested with another sensor which gave the exact same readings as
the other three (I did not swat the sensor, I just plugged
in a spare one). The warning light is still on. Did even a
"no, no!" mod - connected both left front and right front
sensor leads together, so that the ABS control unit would
read only one sensor data for both front wheels :) No
help. I guess the next thing is to try that with rear
sensors as well.

The pump itself is ok, it runs when power is applied directly
into it.

Title: Re: ABS Not working
Post by pappa on Jan 12^th, 2008, 12:53pm

Err...

Has anyone got an idea how the pipes in the hydraulic units are organized?

In my car the hydraulic unit is this:
http://www.fordscorpio.co.uk/manual/brake/ABSHydraulUnit-97.pdf

And I have swapped the engine to -98 2.3 DOHC with
a full wiring loom. The wiring loom is for the -97 onwards
car which has a hydraulic unit like this:
http://www.fordscorpio.co.uk/manual/brake/ABSHydraulUnit97+.pdf

I have the hydraulic (the whole ABS system) for the -97
onwards car. I just don't know which pipes to connect
from the old one to the new one.

Has anyone got any ideas? A picture of the master cylinder
from a 97 onwards 2.3 car might help, but I still would
need to figure out which pipes from the hydraulic unit
go where...

A tough one uh... ?