2006 Toyota Passo ABS problems

[nhealy2677]

Hi
recently abs and emergency brake light came on got it scanned said rear wheel sensors aren't working. Weird they both stopped at same time so checked it out and both on different little looms going into car on their respective sides and along the sill which look fine. bought a replacement abs sensor and still didn't pick up wheel speed. What could be the problem?
Thanks

[Hassan1991]

Did you got brake services or anything?
Wires goes in the abs control unit. Service manual can help you trace the connector then you can use oscilloscope to check if wiring, sensors and triggering pattern are okay or not.

[nhealy2677]

Nah nothing was done just popped up. all wiring looks okay would be weird for it to crap out like that considering it hasn't been touched. Wouldn't be the abs unit and module you think?
Thanks

[Hassan1991]

You have to diagnose step by step. First things should be the sensor pulses.
These things doesn't go bad easily.

[hassannabeel27]

Do check the ABS fuse in engine compartment.

[Xulfiqar]

Check the wiring continuity from the speed sensors to the abs pump wiring, fix any breaks.

Being toyota, the rear wheel wiring will pass through the interior wiring harness, too, each sensor has 2 wires both of which terminate at the abs unit, meaning a total of 8 pins on the pump unit are for the speed sensors.

Finally check if corrossion on the spindle has enlarged the airgap between the sensor and tone wheel.

[nhealy2677]

Checked that through buying another one however didn't fix it and weird that both stopped working at same time so don't think it is sensors

[Xulfiqar]

As I said, you need to do isolation tests rather than throw new parts at it,

the wiring for the rear abs sensors pass through the cabin wiring, check the continuity of the wiring from the abs pump unit to the wheel sensors, They may be broken off somewhere

[nhealy2677]

Yep have checked it on both sides up until where it joins the loom on either side. Will follow it to find where the back ones connect tomorrow as it looks although the front ones go straight up to the plus and in.

[Xulfiqar]

Find the pinout diagram for the abs pump and check the wiring for continuity from the sensor plug to the abs pump.

If you dont find continuity, then find where the wiring broke.

Any rodent damage in the car?

[nhealy2677]

Not that I can see. Have found. diagram and appears both rear sensors connect on the left hand side foot well so I will check down there for a crapy plus or broken wire hope I find something.

[Xulfiqar]

The wiring also connects at the front bulkhead jumbo connectors.

[nhealy2677]

Ok I have found and fixed the problem, this being a bit of corrosion on the plugs on the passenger footwell block causing it to not connect the circuit. I am now trying to fix the horn which won't work.The problem is that it is getting power to fuse however the wire disappears when going into cab which shows it should go into a block of plugs in passenger footwell before going up to steering wheel. I can see the wire leaving the block red with white same as at steering wheel and fuse box but can't find it going from into the box? any ideas?