I have been struggling with an ABS warning light for months now and still can\'t trace the cause.
I have been measuring voltages and would like some kind soul out there to give me a hand by measuring the same place and telling me the result.
I am measuring the voltage on the 2 wire plug giving power to the ABS Hyd unit (passenger side of engine bay). The plug is about an inch across and the 2 wires on mine are red with yellow stripe and black with blue stripe. (I\'ll put a pic up later on)
Disconnect the plug, then, with the engine running, put the black lead of your multimeter onto the negative battery terminal and the red lead onto the plug contacts, one at a time and note down the DC voltage for each.
In my mind, one should carry the supply voltage and the other should be 0v but I\'m not getting this.
So....If you have a multimeter nearby, I would greatly appreciate your help, only takes 2 minutes, I promise!
Thanks guys,
Mark.
I believe Scott SDMINUS is a qualified electrician, Dereham isnt too far away from him.
He might be able to give you a hand.
Gareth
try this first..if the abs warning light is on, open the bonnet and give the relay box on top of the abs unit a little knock with your knuckle. Mine does this sometimes and the unit makes a buzzing noise too. it does the trick everytime.
Hi Gareth,
Trouble is, I\'m no longer in Dereham! Back down in Cornwall now! Thanks anyway.
Robbie, I have put in a new hydraulic unit and the light is still on!! I would be pulling my hair out now if it wasn\'t shaved off!!
Thanks anyway guys, I\'ll keep guessing for the time being....never know, if I leave it long enough, it might fix itself!
Mark.
Does it come on and stay on from first starting the car?
The other cause of that light will be the sensors on each wheel. Have you tried checking the connection to the sensors?
Cheers,
Richard
Yeah, it comes on and stays on all the time. I\'ve slaved in another sensor in place of the front two and still no joy. The rear ones, I have just measured the resistance and they are both 1.1k ohms which is fine. May have to take it to Mazda!! NOoooooooo. I won\'t be beaten if it takes me forever!!
MARK.
i have been watchin this thread, and when it comes to electrical stuff im no expert but i think there are a few things you can try,
i HEAR that the abs sensors are weak and can break when knocked, have you had any work done near them?
do the brakes lock when you stamp on them?
What about an ecu reset tried that one?
i might be stating the obvious or you might have done all this already, but thats where i would start. im confident you will find out what the problem is - as you have a multi meter!! good luck matey.
Hi TurboII,
I haven\'t tested the brakes yet.... I know that sounds daft but I only recently got the car back from engine build and bodyshop. It\'s not registered here yet and I just replaced the brakes, master cylinder and ABS hyd unit and haven\'t had chance to take it out on the road yet! The hyd unit didn\'t cure the fault, I also tried a new ABS control unit and a different ECU. Day before yesterday I measured the voltage on the black wire that supplies the ABS hyd unit and it was 13v, that\'s fine. The red wire should have continuity to earth according to the wiring diagram and the ABS fault finding manual. It does not, it measures 5v?!?! It then says, if there is no continuity to earth, replace the ABS hyd unit. I have done this once already though but I didn\'t measure the old ABS hyd unit connector wires. I have not tried an ECU reset even though I tried a different ECU, can I do this on a 93 model?
Thanks,
Mark.