ABS Pump Relay Waveform

Capture a waveform that shows both the control circuit change when it turns on the relay, and the power switching on to power the ABS Pump. (Use a oscilloscope with two channels to capture this pattern. You may have to carefully set the trigger to capture this.)

Record the waveform below with the time and volts per division.

Y - Axis = Voltage on the switching circuit of the Relay

X - Axis = Time caught in 200ms intervals

Explain with arrows what is happeing in the waveform above.

The Pump Relay switches after 800ms. The Pump Motor then receives a 12v supply at the switching circuit, activating the pump. The Pump then turns off after 200ms and slowly reduces its voltage.

Observe what happens during the ABS Self Test when you first turn the key on. Watch the warning lights, and observe power at the wires with the oscilloscope. Then discuss what is happeing in the ABS system during the Self Test.

As I turn on the key the warning lamp comes up therefore it is doing self test and goes off when everything is clear. The system relay switch closes and voltage pass to Motor Pump Relay and Power at the pump jumps to 12v and then after a few seconds switches off and voltage at the pump goes back to 0v. The lamp then goes off indicating that everything is fire with the ABS.

Create a fault in the system by slowing down a wheel speed sensor or safely shorting out an inductive wheel speed sensor while you are applying the brakes. (Don't short out a Hall Effect or Magneto-Resistive sensor) As you are applying the brakes, notice if the ABS pumps turns on, solenoids turn on, or if the hydraulic pressure changes in one of the brake circuits and shows up on the pressure gauge. Discuss what is happening below:

To make the rotor slow down I manually had to create friction against the rotor. I hold the rotor with my finger before turning on the machine because if I hold after I may hurt my finger. I hold the rotor tight so it doesn't move when I turn on the machine then I realised that the pump did not do self test till I slowly release the brakes so the pump could do self test and goes off before locking the rotor.

Catch an oscilloscope pattern when an ABS solenoid has actuated. What is the pin and name of the solenoid?

How did you do it?

The solenoid wires are 1 Blue ,3 Grey ,5 Green and 7 Yellow .

The solenoids operates as the relay is operated.

Draw the oscilloscope pattern below. Note the time and voltage per division.