abs problem on a 2wd cosworth
09-12-2007, 01:08 PM
#1
abs problem on a 2wd cosworth
hi,when im slowing down for a junction,probably about 5 to 10 mph my abs kicks in and i can feel the pedal pulsing through your foot.the light does not came on when this is happening.sometimes when you first start the car the light stays on for a minute then goes out!any help would be appreciated.
10-12-2007, 05:32 PM
#6
Glennvestite
iTrader: (1)
Join Date: Jul 2006
Location: Darlington county durham
Posts: 62,755
Received 1,042 Likes
on
996 Posts
Check the teeth on the abs pick up ring. IF you can get the sensors out. ForeigneRS are you sure they earth out on the hubs cause im sure they dont. There is 2 wires on the sensors and im pretty sure they dont earth out. I could be wrong though. I had the same fault on my 4x4 cossie. When i changed my osf hub i must of caught the teeth on the pick up ring and bent then ends of the teeth getting the driveshaft to go back in the hub. Ive just tried to make the gap between the teeth bigger and its alot better than it was.
10-12-2007, 06:33 PM
#7
does this problem only occur when the front teeth are rusty?or is it the same for the rears aswell?its pretty annoying and a bit dangerous.
onto something different,just bought a radtec rs500 style intercooler from my pal for £200,its only months old and like new,is that the going rate?
onto something different,just bought a radtec rs500 style intercooler from my pal for £200,its only months old and like new,is that the going rate?
Trending Topics
10-12-2007, 07:20 PM
#8
Testing the future
Originally Posted by glennshute
ForeigneRS are you sure they earth out on the hubs cause im sure they dont. There is 2 wires on the sensors and im pretty sure they dont earth out.
11-12-2007, 06:26 AM
#9
11-12-2007, 01:12 PM
#10
It's not something like you're braking too hard is it? 
Have you got big brakes?
The yellow ABS light can stay on until the ABS controller is happy things are OK - the longest check is for hydraulic pressure from cold, as this can take up to 30 seconds to come to the correct pressure.
It definitely sounds like a wheel sensor is 'lying' to the ECU. The ABS controller is quite dumb and will only do what it thinks is right. The likelihood of it making a bad decision is tiny as it uses two computers which constantly check each other's decisions which must always agree for the system to work properly.
The sensors are inductors and generate an AC voltage as the rotor in the hub rotates. The ECU watches the AC voltage and compares it to a known pattern. When the AC voltage drops rapidly the ECU believes a wheel is locking and activates the anti-lock function.
It's more likely to be a front sensor, as they take a little more abuse than the rears, as amongst other things, their cables twist with steering. You need to measure both resistance AND AC voltage across each sensor. You'll need to jack up the car and have someone spin the wheels for you to do this properly.
On the ABS ECU's plug, meter these pairs and note the results for resistance and AC voltage:
4-22
5-23
6-24
7-25
As the wheel rotates, the resistance and voltage will bounce up and down as the rotor's teeth pass the sensor. At one revolution per second you're looking for 2V AC. Resistance should be between 800 and 1500 ohms.
Holding the multiplug with the pin sockets facing you, and with the cabling at the top, pin 1 and 19 are at the top of the right and left columns respectively - The right hand column are pins 1-18 and the left column is 19-35.
Have you got big brakes?The yellow ABS light can stay on until the ABS controller is happy things are OK - the longest check is for hydraulic pressure from cold, as this can take up to 30 seconds to come to the correct pressure.
It definitely sounds like a wheel sensor is 'lying' to the ECU. The ABS controller is quite dumb and will only do what it thinks is right. The likelihood of it making a bad decision is tiny as it uses two computers which constantly check each other's decisions which must always agree for the system to work properly.
The sensors are inductors and generate an AC voltage as the rotor in the hub rotates. The ECU watches the AC voltage and compares it to a known pattern. When the AC voltage drops rapidly the ECU believes a wheel is locking and activates the anti-lock function.
It's more likely to be a front sensor, as they take a little more abuse than the rears, as amongst other things, their cables twist with steering. You need to measure both resistance AND AC voltage across each sensor. You'll need to jack up the car and have someone spin the wheels for you to do this properly.
On the ABS ECU's plug, meter these pairs and note the results for resistance and AC voltage:
4-22
5-23
6-24
7-25
As the wheel rotates, the resistance and voltage will bounce up and down as the rotor's teeth pass the sensor. At one revolution per second you're looking for 2V AC. Resistance should be between 800 and 1500 ohms.
Holding the multiplug with the pin sockets facing you, and with the cabling at the top, pin 1 and 19 are at the top of the right and left columns respectively - The right hand column are pins 1-18 and the left column is 19-35.
11-12-2007, 01:37 PM
#11
Testing the future
Originally Posted by cozmeister
It's not something like you're braking too hard is it?
i saw from a link that someone posted the other day that it's possible to build a tester for the abs unit
http://www.graynada.co.uk/ and click on 'The FCR' at the top or
http://homepage.ntlworld.com/a.harby2/ggpfcrpg.html
11-12-2007, 10:01 PM
#13
cozmeister,could you just come and fix it?im more a wd40 and wire brush type of guy!ha ha,i dont have big brakes and it is when i am braking lightly below 10 mph it happens,not every time but 7 times out of ten.i have a switched on mechanic pal who i could show your information to and he will make more sense of it.i know exactly what you mean as he has shown me how to read faults etc but i have no equipment or real knowledge of how it works,thanks very much for what everybody has wrote.im sure ill get it fixed with the info. 
11-12-2007, 10:30 PM
#14
A nugget of little known information - the Teves Mk2 system does not perform antilock action below 10 or 5mph (I forget which, more likely 5), I tested this theory last year on the ice while my ABS was actually working 
Suffice to say it's true 
so if this is when yours is 'antilocking' it's more than likely a wheel sensor related problem.
Check the teeth are clean and all intact - a broken or misaligned rotor will raise a fault condition but generally only while driving or when you pull off. A wire brush (well, tooth brush) will help you here The sensors can also provide a duff signal if they have too thick a coating of grease (particularly lithium based grease as it acts like a big resistor) over the inductor at the end of the sensor.
A chap on the RSOC forum had a similar problem to yours, and cleaned in between all the teeth on all four wheel rotors, gave the sensors a wipe and his ABS now works perfectly - but I expect you just have a duff wheel sensor
Mine works once in a blue moon and have finally (hopefully) narrowed it down to the level sensor, which is built in to the cap with the pressure sensor. Just need another one to prove it wrong now
Suffice to say it's true so if this is when yours is 'antilocking' it's more than likely a wheel sensor related problem. Check the teeth are clean and all intact - a broken or misaligned rotor will raise a fault condition but generally only while driving or when you pull off. A wire brush (well, tooth brush) will help you here
The sensors can also provide a duff signal if they have too thick a coating of grease (particularly lithium based grease as it acts like a big resistor) over the inductor at the end of the sensor.A chap on the RSOC forum had a similar problem to yours, and cleaned in between all the teeth on all four wheel rotors, gave the sensors a wipe and his ABS now works perfectly - but I expect you just have a duff wheel sensor
Mine works once in a blue moon and have finally (hopefully) narrowed it down to the level sensor, which is built in to the cap with the pressure sensor.
Just need another one to prove it wrong now
12-12-2007, 09:13 PM
#15
cheers,i am getting the car back next week so ill give the sensors and teeth a good going over,if that fails ill change the wheel sensors 1 at a time till it stops,does the air gap inbetween the teeth and sensor make any difference or is it non adjustable?lee
04-02-2008, 03:52 PM
#21
Too many posts.. I need a life!!
Join Date: Jun 2003
Posts: 671
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by cozmeister
It's not something like you're braking too hard is it? Have you got big brakes?
The yellow ABS light can stay on until the ABS controller is happy things are OK - the longest check is for hydraulic pressure from cold, as this can take up to 30 seconds to come to the correct pressure.
It definitely sounds like a wheel sensor is 'lying' to the ECU. The ABS controller is quite dumb and will only do what it thinks is right. The likelihood of it making a bad decision is tiny as it uses two computers which constantly check each other's decisions which must always agree for the system to work properly.
The sensors are inductors and generate an AC voltage as the rotor in the hub rotates. The ECU watches the AC voltage and compares it to a known pattern. When the AC voltage drops rapidly the ECU believes a wheel is locking and activates the anti-lock function.
It's more likely to be a front sensor, as they take a little more abuse than the rears, as amongst other things, their cables twist with steering. You need to measure both resistance AND AC voltage across each sensor. You'll need to jack up the car and have someone spin the wheels for you to do this properly.
On the ABS ECU's plug, meter these pairs and note the results for resistance and AC voltage:
4-22
5-23
6-24
7-25
As the wheel rotates, the resistance and voltage will bounce up and down as the rotor's teeth pass the sensor. At one revolution per second you're looking for 2V AC. Resistance should be between 800 and 1500 ohms.
Holding the multiplug with the pin sockets facing you, and with the cabling at the top, pin 1 and 19 are at the top of the right and left columns respectively - The right hand column are pins 1-18 and the left column is 19-35.
Have you got big brakes?The yellow ABS light can stay on until the ABS controller is happy things are OK - the longest check is for hydraulic pressure from cold, as this can take up to 30 seconds to come to the correct pressure.
It definitely sounds like a wheel sensor is 'lying' to the ECU. The ABS controller is quite dumb and will only do what it thinks is right. The likelihood of it making a bad decision is tiny as it uses two computers which constantly check each other's decisions which must always agree for the system to work properly.
The sensors are inductors and generate an AC voltage as the rotor in the hub rotates. The ECU watches the AC voltage and compares it to a known pattern. When the AC voltage drops rapidly the ECU believes a wheel is locking and activates the anti-lock function.
It's more likely to be a front sensor, as they take a little more abuse than the rears, as amongst other things, their cables twist with steering. You need to measure both resistance AND AC voltage across each sensor. You'll need to jack up the car and have someone spin the wheels for you to do this properly.
On the ABS ECU's plug, meter these pairs and note the results for resistance and AC voltage:
4-22
5-23
6-24
7-25
As the wheel rotates, the resistance and voltage will bounce up and down as the rotor's teeth pass the sensor. At one revolution per second you're looking for 2V AC. Resistance should be between 800 and 1500 ohms.
Holding the multiplug with the pin sockets facing you, and with the cabling at the top, pin 1 and 19 are at the top of the right and left columns respectively - The right hand column are pins 1-18 and the left column is 19-35.
However, I am not able to get a AC Volt reading across the pins for any sensor.
What am I doing wrong?
05-02-2008, 12:57 AM
#25
Originally Posted by northerner
I've checked the resistance of the sensors via the ABS ECU plug as noted above and 3 are in range, with one not providing a reading.
However, I am not able to get a AC Volt reading across the pins for any sensor.
What am I doing wrong?
If you're getting no resistance reading from one pair it probably means the sensor is either not connected or defective. It may also indicate a wiring fault. Measure the sensor's resistance directly - find its connector, disconnect it and measure the resistance of the sensor at the connector. The front ones are clipped to the chassis rails - I find the front right difficult to reach as its below the turbo heatshield. The front left one is amongst the rats nest below the MAP sensor. The rear ones are under the rear seat bench.
Also, if there's no reading at all, ie infinite resistance, check that the sensor's not gummed up - remove it, wipe off the goop, being careful not to damage the poles of the magnet, and then check again.
To check for a wiring fault for a sensor, disconnect the sensor in question and check the resistance for the shield and the ground for that sensor's cable. Fpr example, Short 4 and 22 together at the multiplug - a paper clip will suffice - make sure you short the right pair! Then measure the resistance at the other end of the cable - i believe this should exceed 100KOhms.
The pairs are wired:
05-02-2008, 05:49 AM
#26
You will never in a milion years get a AC wave signal from a device that is outputting a DIGITAL SIGNAL.
The signal genrated is an on or off signal, it varies from NO SIGNAL to ON SIGNAL.
tabetha
The signal genrated is an on or off signal, it varies from NO SIGNAL to ON SIGNAL.
tabetha
05-02-2008, 04:49 PM
#27
It's not digital mate - the signal comes from an inductor and inductors generate AC. The symbol thats shown on wiring diagrams is an inductor, the same as the crank position sensor and the distributor (or cam) phase sensor. The only digital part of the Teves Mark 2 system is inside the ECU.
I've contacted Teves to find out from them what type of sensor the wheel sensors are, just in case I'm wrong.
Meanwhile, take a look at this site:
http://www.aa1car.com/library/abs1.htm
WHEEL SPEED SENSORS
The wheel speed sensors (WSS) consist of a magnetic pickup and a toothed sensor ring (sometimes called a "tone" ring). The sensor(s) may be mounted in the steering knuckles, wheel hubs, brake backing plates, transmission tailshaft or differential housing. On some applications, the sensor is an integral part of the wheel bearing and hub assembly. The sensor ring(s) may be mounted on the axle hub behind the brake rotor, on the brake rotor itself, inside the brake drum, on the transmission tailshaft or inside the differential on the pinion shaft.
The wheel speed sensor pickup has a magnetic core surrounded by coil windings. As the wheel turns, teeth on the sensor ring move through the pickup magnetic field. This reverses the polarity of the magnetic field and induces an alternating current (AC) voltage in the pickup windings. The number of voltage pulses per second that are induced in the pickup changes in direct proportion to wheel speed. So as speed increases, the frequency and amplitude of the wheel speed sensor goes up.
The WSS signal is sent to the antilock brake control module, where the AC signal is converted into a digital signal and then processed. The control module then counts pulses to monitor changes in wheel speed.
On applications where the wheel speed sensor is not part of the hub or wheel bearing assembly, it can be replaced if defective. Sensor problems can be caused by an accumulation of debris on the end (they are magnetic), incorrect air gap or faults in the wiring or connectors.
By the sounds of it you should be able to stick the sensor to the body's metalwork. Just remember to put it back afterwards.
In contrast, the Mark 20E (not fitted to Sierras) is noted as the following:
I've contacted Teves to find out from them what type of sensor the wheel sensors are, just in case I'm wrong.
Meanwhile, take a look at this site:
http://www.aa1car.com/library/abs1.htm
Originally Posted by AA1CAR
WHEEL SPEED SENSORS
The wheel speed sensors (WSS) consist of a magnetic pickup and a toothed sensor ring (sometimes called a "tone" ring). The sensor(s) may be mounted in the steering knuckles, wheel hubs, brake backing plates, transmission tailshaft or differential housing. On some applications, the sensor is an integral part of the wheel bearing and hub assembly. The sensor ring(s) may be mounted on the axle hub behind the brake rotor, on the brake rotor itself, inside the brake drum, on the transmission tailshaft or inside the differential on the pinion shaft.
The wheel speed sensor pickup has a magnetic core surrounded by coil windings. As the wheel turns, teeth on the sensor ring move through the pickup magnetic field. This reverses the polarity of the magnetic field and induces an alternating current (AC) voltage in the pickup windings. The number of voltage pulses per second that are induced in the pickup changes in direct proportion to wheel speed. So as speed increases, the frequency and amplitude of the wheel speed sensor goes up.
The WSS signal is sent to the antilock brake control module, where the AC signal is converted into a digital signal and then processed. The control module then counts pulses to monitor changes in wheel speed.
On applications where the wheel speed sensor is not part of the hub or wheel bearing assembly, it can be replaced if defective. Sensor problems can be caused by an accumulation of debris on the end (they are magnetic), incorrect air gap or faults in the wiring or connectors.
In contrast, the Mark 20E (not fitted to Sierras) is noted as the following:
Originally Posted by AA1CAR on the Teves Mark 20E
MARK 20E WHEEL SPEED SENSORS
To accomplish the EVBPS function, the Mark 20e system requires a special type of wheel speed sensor. The wheel speed sensors used in all other ABS systems produce an alternating current (AC) voltage signal that changes in frequency and amplitude with the speed of the wheel.
The "magneto-resistive" wheel-speed sensors used with the Mark 20e system work like a Hall effect crankshaft position sensor and generate a direct current (DC) digital voltage signal. A 5 volt reference voltage is sent to each sensor by the controller. The resistance of the sensor changes with wheel speed, producing a digital DC speed signal that is much more precise. This allows the controller to detect subtle changes in wheel speed that can be used for the EVBPS brake proportioning function as well as to detect underinflated tires. The air gaps on the Mark 20e magneto-resistive sensors are not adjustable. The factory air gap specification is 0.28 to 1.42 mm.
To accomplish the EVBPS function, the Mark 20e system requires a special type of wheel speed sensor. The wheel speed sensors used in all other ABS systems produce an alternating current (AC) voltage signal that changes in frequency and amplitude with the speed of the wheel.
The "magneto-resistive" wheel-speed sensors used with the Mark 20e system work like a Hall effect crankshaft position sensor and generate a direct current (DC) digital voltage signal. A 5 volt reference voltage is sent to each sensor by the controller. The resistance of the sensor changes with wheel speed, producing a digital DC speed signal that is much more precise. This allows the controller to detect subtle changes in wheel speed that can be used for the EVBPS brake proportioning function as well as to detect underinflated tires. The air gaps on the Mark 20e magneto-resistive sensors are not adjustable. The factory air gap specification is 0.28 to 1.42 mm.
13-02-2008, 01:58 PM
#30
Too many posts.. I need a life!!
Join Date: Jun 2003
Posts: 671
Likes: 0
Received 0 Likes
on
0 Posts
Ok, I've replaced the duff sensor and all 4 wheels have @ 1050ohms resistance across the sensors (measured from the abs ecu multiplug) which fluctuates when the wheels are turned.
However, the light still stays on......
Any ideas?
However, the light still stays on......
Any ideas?
13-02-2008, 06:01 PM
#31
take the bulb out.i heard somebody mention the abs pump pressurises the system on start up,thats why you hear the pump buxxing when the ignition comes on and that puts the light on,when all is ok it goes out,maybe there is a connection between your problem and this system check
11-03-2008, 02:43 PM
#33
Right - I've finally fixed mine!!! Sort of
Mine was down to the fluid level sensor on the top of the fluid reservoir.
There are two connectors on the cap. The one with three pins controls the red handbrake/fluid level warning light on the dash. The one with two pins is used by the ABS unit to determine the fluid level. When the level is low, the yellow light illuminates. I bridged the pins on the plug and my ABS light went out. I metered the pins for continuity on the cap's connector, and regardless of the float's position, it always reads 'open'.
The answer is to either:
- replace the cap,
or
- be a pirate, and drive around with the connector's wires permanently bridged.
Hope this helps someone!
Mine was down to the fluid level sensor on the top of the fluid reservoir.
There are two connectors on the cap. The one with three pins controls the red handbrake/fluid level warning light on the dash. The one with two pins is used by the ABS unit to determine the fluid level. When the level is low, the yellow light illuminates. I bridged the pins on the plug and my ABS light went out. I metered the pins for continuity on the cap's connector, and regardless of the float's position, it always reads 'open'.
The answer is to either:
- replace the cap,
or
- be a pirate, and drive around with the connector's wires permanently bridged.
Hope this helps someone!
12-03-2008, 05:10 PM
#35
It's not a quick fix for the MOT - if there are other problems, the light will stay on. Bridging these two at the plug for the cap just helps eliminate the fluid level sensor and just as important, the wiring to it. My problem is that the sensor in the cap is no longer connected (somehow) to the pins on the top of the cap. I plan to either replace it or see if I can open it up and fix it. I'll probably replace it as it's easier.
To test if it's working normally, you meter pins 9 and 10 on the ECU multiplug (resistance or continuity) once the system's primed. Assuming a normal amount of brake fluid, if there is continuity, the level sensor is working. If there is no continuity, the ECU thinks the level is low, and disables the anti-lock function, and lights up the yellow light.
Therefore, emulating the connection at the other end, ie diconnecting the connector and bridging the pins for the cable, makes the ABS ECU think the fluid level sensor is reporting the correct level of fluid - normally when there is a low level of fluid, that connection is broken. My fluid level is OK.
So, from cold, ignition to number II, yellow light comes on, self test occurs, fluid level goes down to normal as the system's pressurised, and providing no other faults exist, the light goes out. The yellow only goes off once the hydraulic pressure switch reports OK, the fluid level is OK, and the wheel sensors are OK.
I just thought it would help others rule out or identify the level sensor as a cause of their ABS fault.
To test if it's working normally, you meter pins 9 and 10 on the ECU multiplug (resistance or continuity) once the system's primed. Assuming a normal amount of brake fluid, if there is continuity, the level sensor is working. If there is no continuity, the ECU thinks the level is low, and disables the anti-lock function, and lights up the yellow light.
Therefore, emulating the connection at the other end, ie diconnecting the connector and bridging the pins for the cable, makes the ABS ECU think the fluid level sensor is reporting the correct level of fluid - normally when there is a low level of fluid, that connection is broken. My fluid level is OK.
So, from cold, ignition to number II, yellow light comes on, self test occurs, fluid level goes down to normal as the system's pressurised, and providing no other faults exist, the light goes out.
The yellow only goes off once the hydraulic pressure switch reports OK, the fluid level is OK, and the wheel sensors are OK.I just thought it would help others rule out or identify the level sensor as a cause of their ABS fault.
Last edited by cozmeister; 12-03-2008 at 05:33 PM.
Thread
Thread Starter
Forum
Replies
Last Post
Jack and the Beanstalk
Ford Sierra/Sapphire/RS500 Cosworth
2
09-08-2015 07:03 PM
