ABS debugging..

[steveyd]

Hi All,

From other posts I've found that my ABS is not working and the warning light wasnt warning as some **** had pinched the bulb out of it! So put a new bulb in, and of course it stays on.. (interestingly, it took a few miles for it to come on though).

Next stage is to check all the wheel sensors and one post recommends doing this from the multiplug - I take it this is the plug leading to the ABS ECU? I'm guessing the ABS ECU is one of the shiney boxes behind the glovebox...

I dont have any wiring diagrams yet - can anyone point me to one or tell me which colours are which wheels? Is there one sensor per wheel? I had a merc that had a single sensor at the back in the diff rather than one for each rear wheel.

Also - how easy is it to clean the ABS sensor rotors? I'm replacing the rear brake pads tonight and this seems a good place to start! I'll also check the connections on the ECU as I've read that they can corrode.

Thanks,

Steve

[g8dhe]

The wiring diagrams are on line see the Topics list In Techie Stuff
Here is the ABS for 1997+


Do click the Help symbol to get the best out of the system!

[steveyd]

Excellent -what a useful bit of kit online!

cheers,

Steve

[321Away]

The only ABS fault i've encountered on these vehicles is 1 of the sensors giving a different resistance reading from the others and requiring replacing, ties in with your takes a while to come on (got a Pug that does exactly the same!), i'd recommend unplugging each of the sensors at the plug (wheel end) and taking a resistance reading and comparing the 4.
Julian

[steveyd]

Hi,

I've got one of the rear wheels off to replace the rear pads and I can see the abs sensor - wiring looks good - question is how do I unplug it, it was getting dark last night and I couldnt see much, but I couldnt see any plastic connector - is it right up under the axle? Or is there a way of unplugging from the sensor on the hub?

Also, as mine is a 2wd with a "live" axle rather than driveshafts, the ABS rotor seems to be encase in the axle housing -is it safe to assume it should be free from corrosion as its not exposed to the elements like one on a cv joint would be?

cheers,

Steve

[321Away]

The rears unplug about 30cm from the hub, can be quite tricky to get undone, as they are fixed to the body on a chasis rail going across the car, the fronts arent the nicest and can be found under the battery tray and same position on the other side. In general the sensor tips are normally clean.
Julian

[g8dhe]

Would it not be easier to measure the resistance at the O-08 connector under the dash to start with, then you can look at the wheel that shows a problem ...

All the connectors on a diagram are shown physically at the bottom of the page and then the next page shows where they are located in the vehicle as above.

[steveyd]

Thanks - I've checked the resistance at both the rear sensors - both around 1.6K ohms (I think) - I'll also measure at the 008 connector under the dash - that way I'll be able to tell if theres any breaks in the cables.

However.. I think I've found my problem .. no ABS sensors on the front wheels!!! I've often noticed a couple of unused plugs at the front behind the fog light blanks .. and looking at the diagram on the last post it looks like they are the abs connectors - I'm pretty sure all I can see at the front are the hydraulic flexi hose and thats it... Testing on the 008 connector showing an open circuit should confirm it...

My guess is my one was cannibalised for the 2 front ones.. and later when it came to be sold the bulb was removed to hide it.. Very dodgy and I'm hoping that this was done on the dockside in Japan rather than over here.. (I got it as a fresh import from a respectable garage.. with warranty..).

While we're at it will connectors from other mazdas/xedos fit..?

cheers,

Steve
Steve

[missfixit70]

If it's under warranty, I'd let the garage sort it. Isn't that why you get a warranty?
I don't think anyone's come up with a compatible part , but I'd be surprised if there wasn't one.