[dominicc74]

Hi everyone!

I'm getting the P057129 engine fault code 'Brake switch signal circuit defective or out-of-step correlation'.

The service manual isn't super helpful, and I don't have the wiring digram, just wondering if anyone else has had this code and what they did to fix it?

I have the required tools, multi-meter, etc but I'm struggling to find the connector that connects the sensor on the back of the brake cylinder that hooks into the wiring loom. I'm sure it's up near the top of the front shock somewhere but I'm damned if I can locate it or get to it...

The brake lights work, but the sensor has 4 wires, I'm guessing two separate circuits and one isn't happy.

Any assistance/hints/tips greatly appreciated.

[NMKawierider]

I can't help other then I will PM you a link with the manual and the wiring diagram.

[dominicc74]

just following up on this, I eventually found the connector hidden up behind the front left shock, it was zip-tied out of sight.  after cutting the zip-tie I was able to use the wiring diagram and service manual to check continuity of all the wires to the ECU from the wiring harness and check operation of the two switches inside the brake switch sensor, everything checked out just fine...

I added a bit of Permatex 22058 Dielectric Tune-Up Grease to the connector pins, re-assembed and re-zip-tied, used an app to reset the engine fault codes and have been on a few long bumpy off-road rides and the code hasn't re-appeared. 

In the mean time I ordered a replacement brake switch as it's not too expensive and will replace it if the problem re-occurs.  Part number is 5HY0-080010 - https://www.aliexpress.com/item/1005005933963330.html


notes from my checking at the time, from a month or so ago, including wire-color codes, follows:


Brake switch connector, unplugged:

top two pins, furthest from clip.
GY+GY -> G/Y (0v ignition, B/Br (12v ignition)
open circuit when pedal out.
0ohm when brake pedal in.

bottom two pins, nearest clip
B+B -> G/P, O/R (0v ignition, 12v ignition)
6-10Mohm when pedal out.
0ohm when pedal in.

plugged in, ignition on.
G/P
11V when brake pedal out
0V when brake pedal in

Hope this helps others.