• Welcome to the Contour Enthusiasts Group, the best resource for the Ford Contour and Mercury Mystique.

    You can register to join the community.

ABS light ON and OFF

M

mandzo

New CEG'er
Joined
Aug 10, 2007
Messages
14
My ABS light go ON if I drive 60 mph or faster 1 or 2 min. If i don't drive faster than 55 mph the ABS light never come ON.
When I have the light ON and turn off the car completly, I could start and the ABS light go OFF after a couple of minutes.
I didn't try to get the code(I don't have a code reader), because it seems i need to use it when I am driving.
My suspicious is that one of the wheel sensors is acting strange, but this is only a guess. I am not sure how those wheel sensors behave. Is it possible after 60 mph the wheel sensor to output less than 1.5V AC and cause the ABS module to turn the ABS light ON? Any opinions or experiences with this problem will be much appreciated,
Thanks
 
sounds like you already know what is going on.

Basically the wheel sensors send a basic voltage to the computer stating that the wheel is in motion, my guess is you have a short somewhere in wiring, or one of your sensors is failing. my money is on the failing sensor, because its pretty common.
 
Actually.. wheel speed is generally a pulsed width signal, not a variable voltage.
 
i have this problem with mine. mine is from a bad control arm and a torn up speed sensor. my speed sensor is torn up with metal showing but it never acted up until my drivers side control arm went bad. sounds like yours is purely speed sensor tho.
 
AliasJerk said:
close enough.
Click to expand...


not at all :nonono:

variable voltage would be like the TPS sensor, where the voltage is dependent on possition and it has a range.

pulse width is like it sounds, the teeth in the abs pulse wheel create a pulse and its duration is what is monitored.

so lets think about that, a wheel turning fast will have a short pulse length and a slow wheel will have a long one and one that isn't turning would go to infinity. So the system compares the pulses and if one or more are vastly different from the rest the system knows something isn't right ...

how is that the same?
 
I NEVER said "its the same" I said "close enough" stating that my explanation was enough to state what the issue is and what needs to be replaced "you probably need an ABS sensor, or have bad wiring somewhere."

Was I wrong, about how to repair is issue, Brian? because if I am I want to know where the underlying issue that I am not aware of.
 
Thanks

Thanks

Thank you all for the shared information. Now, I just have to find out which wheel sensor is failing and replaced it.:cool:
 
AliasJerk said:
I NEVER said "its the same" I said "close enough" stating that my explanation was enough to state what the issue is and what needs to be replaced "you probably need an ABS sensor, or have bad wiring somewhere."

Was I wrong, about how to repair is issue, Brian? because if I am I want to know where the underlying issue that I am not aware of.
Click to expand...

no the bottom line was correct, its most liekly a wheel sensor, the the idea you put forth was completely wrong on how they work .... I don't know about you but when I amswer a question I do my best to explain it correctly or I don't comment at all .... lets try to keep answers and discription as accurate as possible as to not cause trouble in the future with confusion ....

so bottom line, if you don't know 100% what you are talking about its best not to answer .... just read and learn from others
 
Just to revisit my question: I had all 4 sensors checked and they are OK. The problem was isolated to the computer, which cost around $1400 I was told. And the advise was to drive with the light ON. Now I am wondering if I drive 50 mph and below and the light is OFF, do I still have a functional ABS system?
 
normally the system is only disabled when the light is on. but with is acting up that maynot be the case.

also whcih computer are you talking about? they maybe a way to get a new one via the junkyard or another member here for way less.
 
Uh, that pulsed signal if read as AC voltage IS a variable voltage, it goes up and down as speed of wheel goes up and down. Indeed, the service data I have says to check the sensor pickup by using AC range on digital meter and spinning wheel, AC volts will move up and down based on speed of wheel. Appears to be an ordinary magnetic impulse pickup. ABS computer may even read it as such, would be far easier for a computer just to compare voltages than to count pulses and require less hardware. Reading AC volt output would be technically the same as reading frequency of pulses since they are locked together.

..............just read and learn from others
 
You must log in or register to reply here.
Back
Top