Strange Problem on 2007 Tacoma

[john_pifer]

The ABS pump/actuator/servo engages randomly. I can hear it engage. When it does this, the speedometer needle jumps around all over the place.

Sometimes, when this happens, the yellow ABS light and the red BRAKE lights illuminate, and sometimes they don't.

Obviously this has the potential to negatively impact stopping distances.

Anyone run into this before?

Incidentally, what IS that whirring noise when ABS engages?

Why would the speedometer needle jump around?



*The back story is that, last fall, the yellow ABS and red BRAKE caution/warning lights came on as a result of a worn out LH rear wheel bearing that developed enough play that the speed sensor for that wheel, which is mounted in the housing for the wheel bearing, was actually being chafed and destroyed, which caused the light. I ended up replacing both rear wheel bearings, axle seals, and that sensor, and the lights went off. Now they are coming on again, albeit intermittently.

Threads here:

https://www.bobistheoilguy.com/foru...ke-warning-lamps-illuminated#Post4922830

https://www.bobistheoilguy.com/foru...g-chafing-wheel-speed-sensor-2007-tacoma

 

[spasm3]

probably a wheels speed sensor, but you need to check the codes. Could be the fronts. I have one on my left front avalanche i need to change. I'll probably change the whole bearing as it comes with a sensor.

 

[john_pifer]

Originally Posted by spasm3
probably a wheels speed sensor, but you need to check the codes. Could be the fronts. I have one on my left front avalanche i need to change. I'll probably change the whole bearing as it comes with a sensor.


Hmm. What about the fact that this ABS servo or whatever it is that makes the noise when it turns on, was not doing that when the LH rear wheel speed sensor failed? Also, the speedometer anomalies never occurred when that sensor was bad, either. Only indication of a problem then, was the ABS/BRAKE lights, and they were illuminated continuously, until I changed that speed sensor. Then they went off.

 

[john_pifer]

Another thing -

If it happens while Cruise Control is on, Cruise disengages and the CRUISE indicator light flashes steadily at a set interval.

 

[BlakeB]

My guess is that a wheel speed sensor is intermittently working. When it messes up the truck sees that you have a wheel or wheels that aren't moving at the same speed as the others, it thinks you're losing control and cancels cruise control and applies "necessary" braking action.

Do you have any codes?
From what I've read on TW, the rear ABS harness is known to corrode on these.

 

[john_pifer]

Originally Posted by BlakeB
My guess is that a wheel speed sensor is intermittently working. When it messes up the truck sees that you have a wheel or wheels that aren't moving at the same speed as the others, it thinks you're losing control and cancels cruise control and applies "necessary" braking action.

Do you have any codes?
From what I've read on TW, the rear ABS harness is known to corrode on these.


This truck doesn't have traction control or stability control of any kind, so it doesn't have capability to automatically apply any or all of the brakes.