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ABS Off light


New Member
Oct 11, 2006
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Members Ride
vs calais 5.0L
G'day Guys
I've got a problem with my VS Calais' "abs off" light coming on.
Only comes on after the cars moving not on start up pre-check passes ok
If I start driving and come up to a corner and start slowing down so the car is just crawling and putting light pressure on the brake pedal causes the pedal to pulsate (the abs coming on pre-maturely) until I stop but the light doesn't come on straight away it's only after a while driving the "abs off" light will come on and the abs is definately off because the pulsing doesn't happen after the light is on.
The light stays on until I restart the car and the process starts again with the brake pulsing etc until the light comes on again. Sometimes if I get onto the freeway before the light comes on it will eventually come on without touching the brakes at all.
I've checked the resistance of both the front sensors and both are 1.7K ohms and while holding the multimeter on them wriggled and moved the wires around the sensor to check for breaks but resistance stayed the same. Checked all the plugs for corrosion but they're ok. Also checked the big plug that goes into the ABS unit that's fine too. Fuse contact points are ok no loose fuses or wires both under the dash and in the engine bay.
I've removed the sensors from both front and back to check for build up of grime on the sensor nose and all were clean. The rear sensors I haven't checked for resistance yet. Have to jack up the car to get to the plugs properly. The rear toothed sensor gears look clean with no build up between the teeth.
Obviously the ABS unit thinks that one wheel is skidding and is applying the ABS but don't understand why it would turn off completely. It sounds very much like one of the sensors is giving incorrect feedback but damned if I know which one.

Holden want to charge $99 to hook up the diagnostics to tell me whats wrong, but being a tight wad I'd just like to know from the experts here whether there is any other checks I can do before I bite the bullet and take it to them to diagnose. No codes come up doing the paper clip trick to read the codes, the only code that is stored is #12 system ok.
I'd love to be able to rectify this problem myself and not give money back to the company that pays my wage :whistling (yes I work for them but nowhere that anyone can help for free lol) So I have a few questions for anyone knowledgable on the ABS system.

Can I hook up the multimeter to each sensor one by one and spin the wheel, I'm thinking I should get some kind of millivolt reading back from the sensor if it's ok?? Does anyone know what feeback reading I should be getting? also assuming it should be an AC voltage reading?

Could it be faulty pressure, air or crap in the ABS unit. Would it be wise to bleed the system to check?

I can't see what the front sensor picks up on as it just goes into a hole, is there a toothed gear in there also? if there is, is there an easy way to see this or do you have to remove the hub assembly? or can I see it just by removing the rotor?

Just take it to Holden and cry about the $99 they charge lol. I'll just have to work Saturday to get the cash back off them :D