No voltage to abs sensor

[bosco659]

I had three dash light come on that prompted me to scan for error codes. Turned out to be no signal from left rear abs sensor. Changed the sensor and the error remained. Upon inspection of the sensor harness I found some animal had chewed through and severed the sensor wire. I did a quick patch job with the intention of replacing the harness.

The wire repair didn’t eliminate the fault. I checked voltage at the sensor and there was nothing. I traced back to the abs module and probed pin #20 which is supposed to provide voltage to the sensor. There was no voltage at the pin.

I’m stumped as to where to look next. I will look underneath the truck to see if there’s any other wiring damage. What puzzles me is how could a rat chewing through my sensor wire, cause me to lose voltage from the module? The other three sensors are functioning properly.

Can the ABS module itself be scanned for faults? Does Toyota have a system that needs to be reset by a Toyota scan tool to restore power to that one circuit?

Any thoughts would be appreciated.

 

[Humble Leader]

I don't have any ideas here but curious to know as well. Rigtec hopefully will post, he seems to know everything about the electronics on these vehicles

Oakville canada? In Jan this year I was parked at a train station all day and came home late at night to find a rodent chewed my ignition wiring

 

[bosco659]

I also had the buggers chew off the wires to my injectors. I get that because the motor was warm and it was a cool night but why they would chew the sensor wire way up above the axle is beyond my understanding.

I spoke to a Toyota Toyota tech and he told me quite a bit about the way the abs works. He said on start up, the ecu sends a voltage signal to the sensor and the ecu checks the sensor sends a signal back to the ecu. Then if all sensors check out, the vehicle runs error free. Since my wire was severed, there’s a possibility that somehow the wire grounded and sent the voltage back to the ecu somehow and may have fried the ecu. I’m hoping that’s not the case.

He confirmed repairs can be extremely expensive and commented the abs units are extremely difficult to bleed.

I’m not sure what to do next. I will replace the damaged harness and hopefully gain some intel on next steps.

Oh and yes, Oakville, Ontario.

 

[Humble Leader]

I also had the buggers chew off the wires to my injectors. I get that because the motor was warm and it was a cool night but why they would chew the sensor wire way up above the axle is beyond my understanding.

I spoke to a Toyota Toyota tech and he told me quite a bit about the way the abs works. He said on start up, the ecu sends a voltage signal to the sensor and the ecu checks the sensor sends a signal back to the ecu. Then if all sensors check out, the vehicle runs error free. Since my wire was severed, there’s a possibility that somehow the wire grounded and sent the voltage back to the ecu somehow and may have fried the ecu. I’m hoping that’s not the case.

He confirmed repairs can be extremely expensive and commented the abs units are extremely difficult to bleed.

I’m not sure what to do next. I will replace the damaged harness and hopefully gain some intel on next steps.

Oh and yes, Oakville, Ontario.

I would claim this through insurance. it would be a non collision claim and your premiums won't increase because of it - assuming you are covered. it cost $1K to fix my injector wiring... if you have injector wiring + ECU issues and other wiring issues it could easily be $2K to $3K parts, labour and tax all in

 

[flyrv9]

Bosco659 - did you try measuring the voltage at the connector for another sensor that's working? Some circuits will not have voltage if there is a disconnect somewhere (broken wire, connector off, etc. Also, an ABS fault may be a latched fault and will not go away without clearing it, even though a repair is made or a connector is reconnected.

 

[weberlukas74]

I’d suggest fixing the harness first and seeing if that solves the voltage issue. If not, check the fuse and ground connections for the ABS module.
Make sure the ABS module itself is receiving the correct voltage supply. If it isn't, it won't send voltage to the sensors.
Also, you can test the ABS module by providing power and checking if it sends the right signals. It'll help you figure out if the module is faulty.