Whats causes ABS to disengage????

[futronix]

reacurring problem..... ABS light comes on sometimes and it feels that the ABS is off at the pedal when braking....... This only happens sometimes and will stay on for no set period of time....

Light will come on starting the car... never really while driving


What can cause this?????

 

[Z()LTAN]

the abs light always come on when starting the car, it needs to charge the lines but i dont know that it would b disengaging

 

[hako]

Check that the ABS fuse is making good contact and also the relay under the bonnet plus the connector to the ABS unit. You haven't pressure cleaned your engine lately? If the ABS is actually operating when braking 'normally' then it means that one of the wheels is telling the ABS that one wheel is locking up and the ABS kicks in and stops braking to that wheel.

 

[futronix]

thanks for your replies....

ill check the fuses and relays tommorow.....

engine hasen't be cleaned lately.....


Z()LTAMAN..... yes I realize that the ABS light comes on when u start, it just seems to stay on longer than it should.....

 

[Dave_4]

it proberly isnt actually disengaging the abs, i have the same problem with my car some times, the light stays on after starting but by switching it off and starting it again it goes off, i had it look at once and i was told it was just a sensor failure

 

[Fletch_QLD]

I am currently having the same problem. Light comes on when I start the car and pretty much seems to stay on. Most of the time if I stop, then restart the car the light goes off.

When the light is on, the abs is non functional - a few quick stops in the wet confirmed this - but if the abs light is not on, abs seems to work fine.

A search of the forum suggests that the abs self test circuit is sensitive to voltage irregularity - and the day this problem started I replaced the gasket on the drivers side rocker cover, this involved pushing and pulling at the wires on the back of the alternator.

My next step is to remove the alternator and check all the wiring at the back, including the regulator. Then I'll swap out with another voltage regulator I have...

Hopefully this'll fix the bug - otherwise I guess it's time to check the 4 x sensors ?

 

[hako]

Good detective work Fletch_QLD.....please post your results - it sounds like you are on the right track.

 

[futronix]

can also confirm that when my ABS light is on that the ABS system isn't working as i found out in the rain the other day!!!!!

 

[kopper69]

There are alot of things envolved with the abs. I would have it professionally checked if you cannot resolve the issue. Ofcourse check fuse and relay as always but if that wont solve the problem there are a number of sensors and modules which can not be checked by the home mechanic. I would be off to the mechanics to get that one fixed.

 

[Fletch_QLD]

Good detective work Fletch_QLD.....please post your results - it sounds like you are on the right track.

Removed my alternator and checked all the wiring - seemed a little loose.
Reassembled taking care with the routing of all wires and since then, no ABS light So far so good.

This could be another reason to upgrade your alternator wiring...
( ie http://forums.justcommodores.com.au/showthread.php?t=5910 )