96 Grand am ABS Light


#1

Hello My 96 Grand Am 3.1 it the SE model. ABS Light is staying on
I check all the fuses all are good I check the wires going to the wheels with a ohm meter
get a reading of 117 ohms driver side and 110 ohms right side .
Need to know if the reading are in specs or not
if I need to replace the ABS unit just the control unit (the black box ) or the whole unit
that mount on the master cly ? the car has no tags right now so I can’t take it to be scan.
Thank you


#2

Until it gets scanned for stored codes, any money spent will be just guesswork, and that always ends up being more costly than doing the job right.

Perhaps a local parts store will rent you a scanner that can read the necessary codes. And perhaps the dealer parts guy will print you a procedure on how to do it. Or you could buy a scanner. The codes you’ll want to see will be “chassis codes” (they start with “C”).

Or perhaps you should get license plates on the vehicle and take it to a shop for a proper read.

The good news is that the majority of ABS CEL codes are caused by wheel speed sensors, or “tone rings” (the ring that the sensor senses) and these are affordable to replace.


#3

@yancey

Does the light stay on when you start the engine?

If so, it could be a bad control unit, relay, blown fuse, etc., for example

Or does it not come on UNTIL you are moving?

If it doesn’t come on until you’re moving, then you may have a dirty or damaged tone ring

If it doesn’t come on until you’re moving, jack up the car and spin the tires as fast as you can and read the signal of each sensor with your meter. Should be at least 500 millivolts AC

By the way, how many sensors does this car have?

I am assuming 4 . . .


#4

There are 2 senors all the fuses I see are good The light come on as soon as the car start stay on alway today I am planing on cleaning the tone rings but it look good as is


#5

Check all your brake lights. It could be as simple as that.


#6

@yancey

If the tone rings were dirty, the ABS light wouldn’t come on until the vehicle was moving


#7

I clean the everything with a wire wheel with some spay cleaner the connection it work the light is off


#8

Be careful cleaning the tone rings. If you get over enthusiastic you can damage them just by doing that. They have pattern on them, and overaggressive cleaning can smudge out the pattern enough so they still appear work, but not reliably.


#9

!!!

Tester


#10

Guys, I think there may have been a misunderstanding

If unplugging the sensors, “clean the everything” and plugging back in fixed the issue, that leaves 2 possibilities, as far as I know

The sensor(s) weren’t properly plugged in . . . which would mean the abs light stayed on at idle, before the vehicle was moving, and before the module saw wheel speed

The sensors were plugged in, but the tone ring was dirty . . . which would mean the abs light didn’t actually come on until the vehicle was moving

In any case, it sounds like OP successfully fixed this on his own


#11

@GeorgeSanJose

Can you please clarify?

I don’t understand “smudge out the pattern” . . . ?!

:cold_sweat:


#12

It is possible to clean a tone ring too aggressively, using chemical treatments, bead blasting, etc. See how the edges in the photo below have a nice square shape to them? If they get rounded over (i.e. “smudged”) it can affect how well the detector can sense them rotating by.


#13

With all due respect, I don’t think there’s too many mechanics bead blasting abs tone rings