Air antilock brake system diagnosis

Question 1

before troubleshooting an ABS system what are some pre checks to first be preformed

Answer 1

. Brake adjustment
. Condition of mechanical components
. Air system operation

Question 2

when visually checking the ABS system what are a few things to look for

Answer 2

. integrity of connections
. physical damage
. tires of unequal size

Question 3

what must you make sure of before disconnecting ABS electrical cables and components

Answer 3

make sure the power is OFF . this will prevent damage to solid state components

Question 4

when using a multi meter to measure a speed sensor how fast should you turn the wheel

Answer 4

1 revolution every 2 seconds ( or 1/2 revolution per second )

Question 5

when checking the tone ring what is the first step before removing any components

Answer 5

wheel bearing adjustment

Question 6

what would you be checking on a tone ring with a dial indicator

Answer 6

runout

Question 7

how can you check the modulator valve for proper operation with it disconnected from the power source

Answer 7

by checking the resistance between the solenoid circuit terminal and the ground terminal

Question 8

what should the resistance be in the modulator valve solenoid circuit 12v or 24v

Answer 8

4.0 - 8.0 ohms for 12 v and 8.0 16.0 ohms for 24

Question 9

the ABS electronic control unit is a

Answer 9

solid state device that requires system power and input signals from the speed sensors to give out put signals to the modulator valves

Question 10

when checking to see if the ABS system is working without looking at the dash light you can also what

Answer 10

listen to the valves cycle one by one then together diagonally 1 2 3 4 then 1&2 3&4