<pedantic mode on>
The ABS system doesn't use vacuum at all. What it is building up is pressure in the metal ball-shaped brake accumulator which you'll see beside the fluid reservoir.
<pedantic mode off>
It then uses this pressure to activate the rear brakes and to assist the front brakes.
You can test if the ABS system is working pretty easily:
1. Find an empty road on a wet day.
2. Get up sufficient speed, 40 mph should be enough.
3. Check that there is no other traffic in sight, neither in front of you in case you skid into their path nor behind you so that they don't have to stop suddenly.
4. Check again.
5. If the road is clear, stand on brakes and clutch with full force.
If the ABS is working, you'll feel the 'chatter' through the brake pedal, if it's not working, you'll skid.
Incidentally, the ABS system is very handy for checking road surface conditions. If you press the brakes a bit suddenly and the ABS activates, the surface is low grip enough that you should drive with due caution...
The ABS system doesn't use vacuum at all. What it is building up is pressure in the metal ball-shaped brake accumulator which you'll see beside the fluid reservoir.
<pedantic mode off>
It then uses this pressure to activate the rear brakes and to assist the front brakes.
You can test if the ABS system is working pretty easily:
1. Find an empty road on a wet day.
2. Get up sufficient speed, 40 mph should be enough.
3. Check that there is no other traffic in sight, neither in front of you in case you skid into their path nor behind you so that they don't have to stop suddenly.
4. Check again.
5. If the road is clear, stand on brakes and clutch with full force.
If the ABS is working, you'll feel the 'chatter' through the brake pedal, if it's not working, you'll skid.
Incidentally, the ABS system is very handy for checking road surface conditions. If you press the brakes a bit suddenly and the ABS activates, the surface is low grip enough that you should drive with due caution...
