Hi everyone,

Reaching out for some advice on an ABS-related problem I’m experiencing with my 2009 Ford Focus Mk2.

Here’s the situation:

The ABS light came on, so I plugged in my OBD-2 Bluetooth scanner and read the DTC C1165, which translates to "Right Rear Wheel Speed Sensor Input Circuit Failure".
I ordered a new sensor assuming it was the root cause and replaced it (worth noting that the old sensor looked pretty clean when removed from the hub). Here's a photo of the new sensor fitted:

In this photo, you can see a green O-ring that I found on the garage floor as I was about to mount the new sensor. I assumed it came from the old sensor.

However, the problem persisted. Upon further inspection of the cable assembly between the sensor and another cable assembly (which I suspect connects to the ABS module), I noticed that one of the wires (the white one) appeared corroded and broken off:

Hoping this was the root cause, I cut and soldered a new two-wire cable to the connector.

Since the new cable was a bit too long, I stripped some insulation off, made a quick loop, and tied it up with a cable tie. I measured 0.1 Ohms between both ends, so it should be fine. However, finding new connectors has been challenging, so I had to rely on the two short remaining wires and the connector itself being in good enough condition:

Unfortunately, this didn’t solve the issue. When starting the car, the ABS performs a self-test but then throws the same error code again with the ABS light on.

I need some input from you guys on this. I’ll upload another photo showing where the cable assembly that connects to the sensor continues, as I’m not sure where the rest of the cable to the ABS module is routed (the wires might be broken off somewhere in between):

I took the car to a workshop to ensure my OBD-2 scanner wasn’t missing anything. The (ex-Ford) mechanic didn’t suspect the ABS ring or the module but thought there might be a broken wire somewhere (this was before I discovered the corroded part).

Any guidance on where the cable routes to or other troubleshooting steps would be greatly appreciated.

Thanks in advance for your help!

 

Best,
Marcus

For the ABS sensor wiring did the inner cores look a decent copper colour where you cut and made the new join?
 

if the wires have gotten corroded this can travel a fair way along the wire and affect connectivity. If the wires were dark or dull brown rather than shiny  copper colour that would indicate that corrosion had travelled further along the wire. 
 

May help to cut into the wiring further back and temporarily run fresh cable to the sensor to see if that helps. 
 

For my mk2.5 ST the ABS sensor wiring was available as a service part, though you do have to cut into the main loom to replace as it’s not a harness on its own.