Without provocation, the ABS fault indicator light came on in my 2003 S-10
after it spent an hour sitting in the sun. The truck is a 2WD V6 extended
cab model with disc brakes in front and drums in the rear. The ABS system
presently can't decide if it's broken for sure or not. When the light's off,
it will demonstrably work. When it's on, it doesn't.
I have started to investigate the problem and obtained some wiring diagrams
from the factory service manual. While doing that, I've noticed something
extremely interesting. The window sticker for the truck *claims* that it has
four wheel ABS. However, the only obvious sensors and related wiring are on
the *front* wheels. There is no immediately obvious way for the ABS system
to sense a loss of traction for the rear wheels during braking!
This seems odd, and it would also seem to nullify the claim that the ABS
system is "four wheel ABS". So...how does that work?
03 uses either the vehicle speed sensor OR a sensor on the rear axle for
It will have a stored code to tell you why the light is on.
The common problem is the backing plate rusts and moves the sensor away
from the tone ring. Next most common is the connector gets corroded and
the next is broken wires in the sensor cables.
(yep, here I am over a month later...the group sure is quiet any more!)
I took it to the dealership branch here in town and immediately got the
feeling they just didn't want to deal with it. Even when I said I'd pay for
the diagnosis, they couldn't be bothered. "Oh, take it to Autozone...they
can read the code."
As I found out, that's not true. Or at least the two guys at Autozone didn't
think their code reader would do it, and they seemed to know.
So I bothered my brother and let him take the truck to his automotive class
one day. It's the left front wheel sensor or its wiring. I paid him $20 for
his trouble (pay attention, dealership guys!).
The light's on practically all of the time now. Only rarely does it go off.
I guess that one of these days I'll pop the wheel off and see what I can
Few of the cheaper Home Tree Mechanic OBDII scanners will do ABS. It is
starting to become more of a option these days on cheaper scanners, but they
are still pretty limited. If it's just a ABS sensor on one of the wheels,
that's a easy enough fix. Most of the time in these cases it's just a bad
Sensor. Usually the cable gets Damaged. The backing plate rusting and
moving the sensor out of the way to not pick anything up would be pretty
rare. It would have to be pretty BAD, almost hanging off. You also
would normally get a different code for a Damaged ABS sensor and one that's
not picking up the Tone Ring.
For example, if your ABS sensor is Damaged, your ABS Self check will fail
without the Car even moving which will turn the light on and stay on without
the Car even moving. On the other hand when you start the car, the ABS
light goes on and self tests and then goes off while your just sitting
there, but then turns on after driving down the street just a bit, then it
could be a Damaged Sensor or a Tone ring Issue. In my experience, 90%+ of
the time, it's a BAD SENSOR someplace on the car. One time I had a Hummer
H2 with bad front bearings. Well the ABS sensor and Tone Ring are in the
Bearing. After Replacing the Bearings with Aftermarket Bearings which
included new ABS Sensors of course, the ABS light would pop on after so many
miles of being driven. After hooking up to a scanner, for some reason the
front sensors were reading a different speed then the rear sensor.
Replaced the Bearings with aftermarket again, and the exact same issue.
Went and got O.E. bearings and that fixed the ABS problem. I didn't get it
all. How that could be?!?! They were for a Hummer H2, they Mounted up
correctly, plugged in just fine, and yet wasn't reading right. Easy enough
to replace, but still a big waste of time. That was a strange one.
There's no Clear ABS codes on ABS systems like on OBDII systems. They will
clear themselves when the problem is fixed! If your ABS light is ON, your
ABS system is disabled!!! I would get it fixed, if your ABS system just
sits there, you'll have other issues later on from the system on being used
and just sitting there. Then you could have a quite costly repair later on.
A Sensor is pretty cheap generally. Just about everything else is not.
wrote in message
On Thu, 16 Mar 2017 15:58:45 -0700 (PDT), email@example.com
Does the ABS light come on with the key, stay on a few seconds and go
out, then come on when you start to move? Or does the light come on
and stay on without moving the truck? If the light comes opn when you
start to move it is a sensor output problem - sometimes a bad sensor,
sometimes a bad "tone ring" and sometimes just a dirty ring.
If the light comes on and stays on without moving, you have a bad
circuit - either an open or a short - could be a failed sensor or a
You need to check the codes to know which wheel. I believe there is a
way to test with a ameter and a jumper wire - check the shop manual
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