mmccabe

My pf had abs light comeon. I read the code as 31, checked the right rear sensor with my meter and it was dead. So I replaced it. I cleared the code and went for a drive. After one minute over 20 mph the abs light comes back on. I read this code as 18. The manual says" code 18----sensor rotor or abnormal tire size." That is not enough info to get me working again. The tires are not abnormal.

mmccabe

updating my abs problem. ...... Now everytime the engine is shut down the abs light goes off when I restart nut the light comes on after driving a little. While the light is off the brakes are solid except right as the vehicle stops the brakes feel like there tapping and the pedal sinks to the floor. Any solutions? anything?

golfer

Was this happening before you found and replaced the dead sensor or after ??

When you say " tapping" are you talking about the brake pedal pulsing ??

Do you hear the ABS actuator coming on with this " tapping " ??

mmccabe

Before I changed the sensor the ABS was non functional.... the rear would lock up on any surface. After the sensor change the problem changed. Now the brake pedal is stiff and feels good until just before stopping. Right at the stop point the pedal goes soft and on the way to the floor it taps back a few times rapidly, and the pads release enough to have to jam the brake down to make the complete stop. Every time I turn the engine off and restart it the Abs light goes back off, until I have driven over a minute then the light comes on and the brakes are just hard to use.

mmccabe

I dont guess I can hear the abs actuator, although Im not sure what it sounds like. There are no loud or wierd noises.

golfer

Was the ABS light on at that time?


When you originally found and corrected the faulty sensor , did you check the others and the connectors for damage and / or corrosion ?


There is a test you can do to see if this if this just an ABS problem.

Warning this is just for testing only and not a fix.

If you remove the 7.5 amp fuse , I believe, number 28 ; this will disable the ABS controller and you will have regular brake operation. This will make sure there is no other brake issues ; air , leaking , etc.. If this checks out the regular brake system then it isolates it to just an ABS issue. Just be cautious when you're driving doing this test.

Code 18 is also is for the sensor rotors which are attached to the back of the front brake rotors and the back of the rear drums.

These are round and have teeth , similar to a chain sprocket , these are what the sensors are reading. Look for damage , broken teeth or build up of debris on the rotors. Another thing is to check the wheel bearings axial end play.

The sensor is reading , gap, no gap , etc. and sends this pulsed signal back to the ABS controller. The controller looks at this information ( from each wheel ) and determines that if the pulses are the same ( for all 4 ) then no wheel slippage or lock up and no need for ABS to come on.

If one of the sensor rotors is damaged or the wheel bearings are shot then the gap , no gap timing pulses are unusual and the ABS controller is fooled into thinking that one or more wheels are slipping or locked up , engages to compensate.