I'm new to the forum so I apologize if this request for help is a little long:
I need help regarding the ABS on my Tacoma. It is a 2000 4X4 5 speed V6 TRD. Now for the problem. Initially, on about every third start-up, my ABS light would come on and remain on for the entire trip. Other times, the light would extinguish upon start-up and remain off during most of my trip (some of 5 miles, some of 100 miles). There was no identifiable pattern regarding when the light would come on during that trip or what, specifically, I was doing when the light chose to reveal itself. Many times, I was on the freeway at speed, not touching the brakes when the light would appear.
Recently, the ABS light starting coming on (and remaining on) after every start. I queried the ABS computer and discovered I had faults 32 (L/F sensor), 44 (decel sensor), and 49 (brake light switch). I pulled all four wheel sensors, cleaned them up, and correctly re-installed them. No difference. I decided against replacing the L/F sensor at this point in time because almost everyone else with the exact same codes did so to no avail. I next pulled the wire plug that plugs into the ABS computer, cleaned up the male pins (including a slight tweak), applied a small amount of dielectric grease, and reinstalled the plug. The ABS light on the dash now went out after its initial 3 second “test on.”
I thought I had solved the problem. NOT. I went for a ride. As I was coming to a stop, the ABS function (vibration in the brake pedal and a ratcheting sound) occurred at about 5 MPH to stop. The first time, the ABS light stayed off, however after the second stop with the same symptoms, the light came back on (and of course, now the 5 MPH vibration was gone – ABS obviously again disabled). I went under the hood and “re-positioned” the ABS plug wires (coming out of the 90 degree ABS wire plug). The light now went off. Again I thought I had identified the problem (wiring at the plug) and had solved it with the re-positioning using a tyrap to hold the wiring in a slightly different orientation.
Now, the light will consistently go off upon start-up (after its 3 second “light-on” test) giving the mistaken impression all is OK. The ABS will activate from 5 MPH to stop about 60% of the time (approximately every other stop). That activation is not predictable. Sometimes, I will have 4 stops in a row that are normal, then have two or three with the vibration. The light is still off (after its 3 second “test on”) on every start-up. With the light off one would assume no faults in the system or the light would remain on), I again queried the ABS computer. I still had the three codes (32,44,49). I decided to clear the ABS computer and see if the fault codes would reappear. Once erased, no faults re-established themselves in the computer's memory. The ABS activation however continues as previously described with no change.
Now for the questions. With the light off and now no faults stored in the memory, one would think the computer believes all is well. Why is the ABS function consistently activating at under 5 MPH on dry pavement with no wheel slippage? Why not activate at 30 MPH? What is the computer seeing at 5 MPH that is causing it to activate? Could one of the wheel sensors be dropping out at that low speed, confusing the computer? Is this symptom someone recognizes that they have solved? If so, what was the solution?
Is is possible I have one sensor with a weak magnet? The sine wave is easily generated at higher rotational speeds with a weak magnet, but at lower rotational speeds, the disruption speed of the tone wheel teeth in the magnetic field is not enough to generate the sine wave needed by the computer due to that weak magnetic field. Could that lack of a sine wave (assuming that is what is actually happening) at lower speeds cause the computer to believe that wheel has stopped, thus it initiates the anti-lock function?
I was told by one tech that these wheel sensors don't work at under 5 MPH by design. If that is true, what is the computer receiving that is causing it to activate? If the above is true, it stands to reason a correctly working system would stop pulsating the brakes at under 5 MPH on ice. Is that what happens? I live in Northern California so we don't have snow or ice.
I cannot help but believe I have a wiring problem at the plug. The movement of the wires apparently does have an effect on the computer function. I need help from someone who has solved this problem. Once erased, the codes (32, 44, 49) have not reappeared. The ABS computer believes all is well.
My only other thought regarding this issue is with the wheel sensors themselves. If one of the sensor magnets is weak (but operational), the tone wheel teeth would still easily generate the sine wave the computer is looking for during its pass through its magnetic field at higher revolutions. I know the AC voltage generated is directly proportional to the magnetic flux density of the magnetic field and the rotational speed of the tone wheel. When the rotational speed of that tone wheel slows, the above factors could result in a lower than expected induced voltage sent to the ABS computer. Depending on the programming of that computer, it might ignore that “reduced voltage.” If it were to read that reduced voltage as “no voltage” at one wheel, that signal would be translated into “no rotational activity.” The computer would assume that one wheel has locked up (no rotational signal) and trigger the anti-lock function.
It's possible the weak sensor would ohm-out within specs yet not have a strong enough magnetic field to satisfy the induced voltage needed by the ABS computer at low rotational speeds. Has anyone solved this problem with the above symptoms? If so, what is the solution short of mindlessly throwing parts at this problem or disconnecting the ABS function altogether?
I need help regarding the ABS on my Tacoma. It is a 2000 4X4 5 speed V6 TRD. Now for the problem. Initially, on about every third start-up, my ABS light would come on and remain on for the entire trip. Other times, the light would extinguish upon start-up and remain off during most of my trip (some of 5 miles, some of 100 miles). There was no identifiable pattern regarding when the light would come on during that trip or what, specifically, I was doing when the light chose to reveal itself. Many times, I was on the freeway at speed, not touching the brakes when the light would appear.
Recently, the ABS light starting coming on (and remaining on) after every start. I queried the ABS computer and discovered I had faults 32 (L/F sensor), 44 (decel sensor), and 49 (brake light switch). I pulled all four wheel sensors, cleaned them up, and correctly re-installed them. No difference. I decided against replacing the L/F sensor at this point in time because almost everyone else with the exact same codes did so to no avail. I next pulled the wire plug that plugs into the ABS computer, cleaned up the male pins (including a slight tweak), applied a small amount of dielectric grease, and reinstalled the plug. The ABS light on the dash now went out after its initial 3 second “test on.”
I thought I had solved the problem. NOT. I went for a ride. As I was coming to a stop, the ABS function (vibration in the brake pedal and a ratcheting sound) occurred at about 5 MPH to stop. The first time, the ABS light stayed off, however after the second stop with the same symptoms, the light came back on (and of course, now the 5 MPH vibration was gone – ABS obviously again disabled). I went under the hood and “re-positioned” the ABS plug wires (coming out of the 90 degree ABS wire plug). The light now went off. Again I thought I had identified the problem (wiring at the plug) and had solved it with the re-positioning using a tyrap to hold the wiring in a slightly different orientation.
Now, the light will consistently go off upon start-up (after its 3 second “light-on” test) giving the mistaken impression all is OK. The ABS will activate from 5 MPH to stop about 60% of the time (approximately every other stop). That activation is not predictable. Sometimes, I will have 4 stops in a row that are normal, then have two or three with the vibration. The light is still off (after its 3 second “test on”) on every start-up. With the light off one would assume no faults in the system or the light would remain on), I again queried the ABS computer. I still had the three codes (32,44,49). I decided to clear the ABS computer and see if the fault codes would reappear. Once erased, no faults re-established themselves in the computer's memory. The ABS activation however continues as previously described with no change.
Now for the questions. With the light off and now no faults stored in the memory, one would think the computer believes all is well. Why is the ABS function consistently activating at under 5 MPH on dry pavement with no wheel slippage? Why not activate at 30 MPH? What is the computer seeing at 5 MPH that is causing it to activate? Could one of the wheel sensors be dropping out at that low speed, confusing the computer? Is this symptom someone recognizes that they have solved? If so, what was the solution?
Is is possible I have one sensor with a weak magnet? The sine wave is easily generated at higher rotational speeds with a weak magnet, but at lower rotational speeds, the disruption speed of the tone wheel teeth in the magnetic field is not enough to generate the sine wave needed by the computer due to that weak magnetic field. Could that lack of a sine wave (assuming that is what is actually happening) at lower speeds cause the computer to believe that wheel has stopped, thus it initiates the anti-lock function?
I was told by one tech that these wheel sensors don't work at under 5 MPH by design. If that is true, what is the computer receiving that is causing it to activate? If the above is true, it stands to reason a correctly working system would stop pulsating the brakes at under 5 MPH on ice. Is that what happens? I live in Northern California so we don't have snow or ice.
I cannot help but believe I have a wiring problem at the plug. The movement of the wires apparently does have an effect on the computer function. I need help from someone who has solved this problem. Once erased, the codes (32, 44, 49) have not reappeared. The ABS computer believes all is well.
My only other thought regarding this issue is with the wheel sensors themselves. If one of the sensor magnets is weak (but operational), the tone wheel teeth would still easily generate the sine wave the computer is looking for during its pass through its magnetic field at higher revolutions. I know the AC voltage generated is directly proportional to the magnetic flux density of the magnetic field and the rotational speed of the tone wheel. When the rotational speed of that tone wheel slows, the above factors could result in a lower than expected induced voltage sent to the ABS computer. Depending on the programming of that computer, it might ignore that “reduced voltage.” If it were to read that reduced voltage as “no voltage” at one wheel, that signal would be translated into “no rotational activity.” The computer would assume that one wheel has locked up (no rotational signal) and trigger the anti-lock function.
It's possible the weak sensor would ohm-out within specs yet not have a strong enough magnetic field to satisfy the induced voltage needed by the ABS computer at low rotational speeds. Has anyone solved this problem with the above symptoms? If so, what is the solution short of mindlessly throwing parts at this problem or disconnecting the ABS function altogether?
