12 replies to this topic

[QuangB]

Hi, can anyone help me out?
i've had this problem since i got my car last year, was told it was the rear right sensor, got a second hand one from sunspares, replaced the old one which was clean (also turns out it within specification 1.2K ohm, good on ya subaru for just hooking a computer up but not checking). I've checked continuity from the sensor into the harness in the drviers side foot well and there is no problem. Visually looking through the abs hole, the tone wheel looks ok, but it does have some faint scratches on it.
Any ideas?
Thanks

[Shaz]

I had that issue with my Gen 3 Wagon when I replaced the motor.

Turns out the ABS unit itself was faulty/incorrect.

Swapped it out, and it was good to go.

Cheers,
Shazza

[RX25SE]

Did a scan tool come up with a RR sensor code?

Good you checked resistance but you should also check sensor output to confirm it's signaling the ABS ECU.

The sensor outputs a A/C voltage as the wheel rotates. From memory its about 0.1- 1v depending on wheel speed.

As wheel speed rises, so does the voltage (amplitude) and the pulses speed up (frequency increases).


You can test the voltage output with a multimeter set to A/C volts.

[QuangB]

Hey RX25SE, yeah i had previously taken the car into subaru and the diagnostic tool said it was the RR sensor.
It was 400 odd for a new one and it was on back order from japan so it would have taken 6 month (or more) to get it in.
Sunspares had a used one with guarantee so got one of those, annoying thing my original one come up to spec in resistance, but i would have expected subaru to check the sensor as i had asked them too and not just rely on the computer.
Since its just a matter of hooking up the multimeter on AC to check the voltage thats a quick one i can check too, thanks!!!

Next one i'm going to check is from the harness in the drivers side foot well to the connector at the ABS control unit.

[Cam.]

Never rule out a broken or damaged wire or connection.

If Subaru said it was the RR sensor and the 'damaged' sensor is giving out a reading within specs, Switch a sensor over and see what happens to rule out a dodgy sensor.

Check all wiring before replacing the ABS unit, Hopefully it's something simple.

[QuangB]

SW4GON, i have swapped out the sensor and so far checked the wiring from the sensor to the harness in the drivers side foot well (continuity checks). Need to check from there to the ABS control unit now.
Does anyone know if the ABS code faults need to be cleared before the light goes off? As that is what subaru is telling me and want 110 to clear it.
However, the light did go off for a day when i disconnected and reconnected the the sensor once. Which makes me wonder if i really need to clear it.

[RX25SE]

You may find that the light will go out when the fault is fixed. It will probably have a code sitting in the history files after the fault has been fixed. You will a scan tool to clear it.

[Cam.]

ABS codes will usually stick around until cleared by a scan tool.

Where abouts are you from?

[QuangB]

Hmmm, maybe i do need to clear it after all.
SW49ON im from canberra. Does anyone know how to clear the ABS codes without the scan tool?
I had access to a OBD2 scan tool but it came up with nothing, i don't think it picked up ABS codes only engine codes.

[RX25SE]

Are you sure you car is OBDII?

I has the 16pin plug but Im sure it runs a different protocol.

[QuangB]

Yeah, just had a quick look on the net and service then, everything says obdii. What do you mean by protocol?

[RX25SE]

Type of langauge used. You can work it out by seeeing which pins are populated in the 16 pin OBD plug.


I could be wrong but I scanned mine the other day and had no "P" codes. Mmmmmm might look again.

None of this will help with your problem though!




You could try leaving the battery disconnected for a while but I doubt it will work. Most likely you will need a scan tool, espcially if its OBDii.

[QuangB]

In the service manual it says you can do it manually. but i can't locate the diagnosis terminals shown on ABS-19 of the service manual.