ABS Light

[Fox 5.0]

My ABS light came on the other day and now is on at all times when the car is running. From doing research on the internet, it seems like everyone suggests actually going to the dealer to get it diagnosed. Is this true? I have no issues with the braking system that I know, everything seems to work fine. I do get a little bit of a noise from I think the rear drivers side, like the rotor is warped or something (makes a rhythmic noise when applying the brake). Either way, suggestions?

 

[SNAKEYE]

My ABS light came on years back after I washed out the engine bay. I borrowed an ABS scanner tool that told me the left rear was the problem. I tested the continuity of the left side and compared it to the right side. Al readings the same. I replaced the rear wheel sensor and cable section because the sensor was retracted into its mounting. No change. I have not torn the ABS unit out because its beneath the Vorech supercharger, and I am not going to pull it out of the car. I've learned to live with the light. Like you say everything seems to work.

 

[BranL]

Might seem dumb but low brake fluid? Happened to me once..

 

[Fox 5.0]

Found my issue. Put the car up on ramps to check the sensors for any visual damage and low and behold the drivers side rear sensor wire i guess came loose and was rubbing against the inner side of the rim to the point it completely severed the wire (except the sheathing on one side).

My next question is which replacement sensor do you guys recommend. I usually buy parts through RockAuto.com but they don't have Motorcraft replacement sensors for the drivers side rear... all other corners, but not the one i need, go figure. They have Standard Motor Products or Airtex. I could buy Motorcraft through LateModelResto. Also, do I need to replace both sides or am I fine just replacing the one sensor?

Thanks

 

[SNAKEYE]

I got the piece that goes from under the rear seat to the wheel at a pull-it-yourself junkyard. Didn't solve my problem. And like I said earlier I ran continuity checks and all was comparable left side to right side.

I am going to try BranL's possible solution. I topped up the master brake cylinder today (it took a couple of ounces, which surprised me), but the weather was too rainy to take a test ride. Perhaps tomorrow the weather will cooperate? I will report back either way.

 

[SNAKEYE]

Still no test ride, but I fired it up in the garage, pumped the brakes a few times, and the light is still on.

May get it out for a ride tomorrow.

 

[SNAKEYE]

Put about 10 miles on today.
The ABS light is still lit.
So much for that.

 

[19Mystic96]

there should be an ABS diagnostic point near the fuse box.

by placing a wire where the arrows are in this pic (stolen from another thread) you can make the ABS light blink a code to tell you whats wrong with it..



edit: here are the codes you'll be looking for..

sit in the car and turn the key to " on " position and count the number of times it blinks.

Here are the error codes:

12 - system ok
19 - anti-lock control module
22 - right front valve
24 - left front valve
26 - rear valve
31 - right front ABS sensor continuity fault
32 - right rear ABS sensor continuity fault
33 - left front ABS sensor continuity fault
34 - left rear ABS sensor continuity fault
41 - right front ABS sensor
42 - right rear ABS sensor
43 - left front ABS sensor
44 - left rear ABS sensor
61 - pump motor/pump motor relay fault
63 - voltage supply interruption
69 - vehicle battery voltage less than 10VDC
78 - ABS sensor frequency fault

 

[Fox 5.0]

Sorry to hear about your troubles SNAKEYE. I'd like to report that after replacing the damaged sensor with a new Motorcraft sensor from LateModelResto, all is well. Hope you can figure your issue out.

 

[SNAKEYE]

Thanx 19Mystic96 for the diagnostic info, but like I mentioned earlier I had a mechanic friend come around with his ABS scanner that indicated it was a left rear issue.
I replaced the wheel sensor because it was retracted (???) into its mounting bracket thus increasing the air gap. I checked the continuity of both rear ABS circuits from rear to front and front to rear. Each respective reading was the same. I even went as far as getting another ABS module at a salvage yard, that I never tried to install because of having to move the Vortech SC out of the way to get access.
So I'm living with it.

As for whether the ABS light blinks at startup, it does not, just stays on steady.

I'm out of here as I am in the middle of compounding and polishing SNAKEYE.

Drive on.

 

[Fox 5.0]

Is anything wrong with the hub or the teeth on the hub that the sensor reads from? I didn't know how the ABS sensor worked until I took it off... looks like the metal (magnetic) sensor rod sits super close to that gear looking wheel/hub inside the rear brake disc. Maybe if one of those teeth are bent or got f'd up somehow its throwing off the magnetic pulse reading??

I assume this is how the ABS sensor works, lol.

 

[SNAKEYE]

Basically that is how it works. Kind of like in an electronic ignition where a magnet on the rotating shaft of the distributor spins on by a stationary sensor creating a small pulse that electronically triggers the spark to a sparkplug.

The air gap is important, but I don't think my issue is air-gap related. My problem started after very carefully washing out the engine bay. Water must have gotten into some connection somewhere and messed it up.

Anyway, back to "wax on, wax off"!

 

[CzchMex]

I've had the same issue but that was because it developed a magnetic charge and metal shavings from the brakes would stick to it like metal to a magnet. Once cleaned it would turn off.

I also get it because my rear tires are bigger than my front. And when I three wheel it into a parking lot it triggers it