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Scott Shepherd
12-22-2009, 9:23 AM
I have an older Ford Explorer that I rarely drive. Probably gets less than 2,000 miles a year. It was up for inspection, I knew it needed brakes, but it was pouring down rain and cold, so I decided to take it to a mechanic and let them do it. No ABS lights were on, nor had they been on. I took it in, got the call "You need a new caliper, but if you don't drive it much, it'll probably be okay for a while, just keep an eye on it".

Drove it home and parked it. Took it out 2 weeks later, the ABS light is on.

Don't really want to drop any more money into it at this point, but I find it odd that the ABS light came on after they worked on the brakes. I've installed brakes on that truck numerous times and it's not anything to it, and I've never had that light come on after putting pads or pads and rotors on it.

I'll probably end up fixing it myself, so I'm just curious as to what might be the cause of that. It's full of brake fluid, and the pads are new. Not sure what else I need to check in that system.

Any ideas?

Tom Godley
12-22-2009, 9:30 AM
I had a problem with rust on one of the wheel sensors on a car that was not driven very often - causing the light to come on.

But many things can cause the light to come on.


Did they take the caliber off the car?

Paul Ryan
12-22-2009, 10:12 AM
Either take it back and have them check the sensors, or if you are worried they will try to stick it too you, then. I assume you just had the front brakes done, nothing with the rears. Take the front wheels off and check the sensors. There will be a tone wheel, around the front axel inside the rear of the brake rotor. The sensor needs to be about the thickness of a nickle away from the tone wheel. If there is rust on the sensor that wont allow it to sense the magnetic pulses fromt the tone wheel. The sensor has a magnet in it, and the tone wheel is a ring with teeth on it. As it rotates the metal teeth come across the sensor and create a pulse. Since the sensor is magnetic it will attract rust. If there isn't any rust on it check the wires, and the tone wheel, make sure they didn't damage the tone wheel, or the sensor. It should be easy to find the cause yourself. I would take it back 1st though.

Jason Roehl
12-22-2009, 10:16 AM
If it's a '96 or newer, take it to an auto parts store and have them read the OBD-II codes, most do that for free these days. A more specific code related to your ABS may come up.

Scott Shepherd
12-22-2009, 10:34 AM
Thanks! Yes, it's sat still for about a year with no driving at all, so the rust might be an issue. They did not take the caliper off the truck.

I'd rather not take it back to them at this point. Not sure I'm trusting them, but the jury is still out. I'll check it and see if that helps. If not, we'll take it to the next level.

Thanks!

Lee Schierer
12-22-2009, 11:20 AM
I had an Explorer and had ABS problems. I needed new rotors and had them installed. The mechanic broke one of the sensors so a new onee had to be put in. The mechanic put in new sensors, but didn't clean the rust out of the sockets so the sensors weren't close enough to the rotor. The cure was to clean out the rust and resinstall the sensors. The cables on the old sensors are apparently rather fragile so working around old ones can cause them to break.

Paul Ryan
12-22-2009, 12:56 PM
Unles the Auto parts store has the seperate ABS tool they wont be able to read ABS codes. The ABS has its own serperate moduel that the codes get stored in. If you have put brakes in yourself before it wont be hard for you to fiqure out what the problem is. Provided it is something with a wheel speed sensor, which most likely it is since you just had the brakes done.

Joe Pelonio
12-22-2009, 10:49 PM
As I recall on the older Explorers, there is only the ABS light for the brakes. That means it will light if a stoplight bulb is out. Check those first, just in case.

I've also seen the sensors get messed up or plugs loosen from snow and ice, if you have had that sort of weather lately.

Ben Hatcher
12-23-2009, 10:55 AM
Though it isn't likely the cause of your problem one thing that I learned about these ABS sensors is that since they are magnetic, they attract metalic brake dust and bits of your rotor if your pads are too hard. So, when you change your pads, be sure to put the right kind back on. I think that I had semi-metalic ones installed on mine last time and that ABS sensor got buggered up every 3k miles.

George Lesniak
12-23-2009, 1:33 PM
Scott,

Could you provide some specifics on your vehicle? (Year etc) I could look this up on our information system and see if there is a manual method for pulling ABC codes.

George

Scott Shepherd
12-23-2009, 2:51 PM
Thanks everyone! George, it's a 2000 Eddie Bauer version, 4WD.

George Lesniak
12-24-2009, 12:58 PM
Thanks everyone! George, it's a 2000 Eddie Bauer version, 4WD.

OK, I just read through much of the ABS diagnostic information on the Ford OEM service info website. It appears there is no manual code retrieval on this system. So, without an ABS capable scan tool, diagnosis by DTC is not an option. AutoZone is not capable of pulling ABS DTCs.

Ford did list several things to check which could illuminate the ABS light:

Check the following fuses:
Central junction box (CJB) Fuse 11 (7.5A), Fuse 14 (10A)
Battery junction box (BJB) Maxi-Fuse 3 (50A)
BJB Mini-Fuse 7 (30A)

Insure tire pressures are to specification.
Check brake light operation. (burned bulb)

Ford also lists a technical service bulletin (TSB) for the rear ABS speed sensor (in the differential) picking up metal particles from the ring and pinion and setting a DTC.

In my opinion, if the shop that serviced the brakes did something wrong the light would have come on during drive home, not after 2 weeks.

After looking at the wiring schematic for this system we may be able to apply some logic and develop a diagnostic process based on the way this system functions. If you pull all 4 of the fuses listed above you will remove all power from the ABS module. Leave the fuses disconnected for a few minutes and then reinstall fuses. (you may want to keep the fuses out as long as 30 minutes to be sure the capacitors have drained and ABS memory has been cleared.) Any ABS DTCs should now be cleared. Turn the ignition key on. The ABS light should illuminate as a bulb check and go out after a few seconds. If this does occur the system is now operating normally. If the light stays on the problem is still present. If the problem is present with the key on it is not a dirty or contaminated speed sensor. The sensor may be open circuit but it is not contamination causing the light.

If the light did go out after the bulb check, start the engine. Now step on the brake a few times.)with the vehicle sitting still) If the light is still off, the problem is not in the brake light circuit. If the light comes back on at this time check the brake lights and brake switch and wiring.

If the light is still off it's time to drive the vehicle and watch the light. If the light come on during a test drive recheck tire pressures and physically inspect the 3 ABS wheel speed sensors to be sure the are connected and the wiring is not damaged. If this doesn't find the problem it's time for a more thorough diagnosis.

Go through the above process and let me know at what point the ABS light illuminates.

George

Ethan Vos
12-24-2009, 2:05 PM
Drive a screwdriver through bulb in the dash.....:D