ABS Relays

Record the name of the relay or switch that powers up the ABS ECU:

S13

Record the name of the relay or switch that powers up the ABS Pump:

K100

Record the name of the relay or switch that sends power to the ABS HCU solenoids:

K39

Relay Wire Identification:

What is the ECU pin number for the wire that brings in the power to the ABS ECU?

25

What is the ECU pin number, or other number, for the wire that controls the relay for the ABS ECU?

1 SW RT

What is the pin number for the wire that brings in the power to the ABS Pump?

14

What is the pin number, or other number, for the wire that controls the relay for the ABS Pump?

28

Relay Waveform: Capture a waveform that shows both the control circuit change when it turns on the relay, and power switching on to power something in the ABS system.
(Use the 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, and explain what are you measuring.


Explain what is happening in the waveform above.







ABS Pump Relay Waveform: Capture a waveform that shows both the control circuit change when it turns on the relay, and power switching on to power the ABS Pump.
(Use the 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, and explain what are you measuring.


Explain what is happening in the waveform above.

Control Relay takes 0.8 seconds to turn on, then 2 seconds to turn off.


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 happening in the ABS systems during the Self Test.

Orange light turns on, during this time the power circuit turns on then off twice, then the orange light turns off. Power Circuit when on switches to 12V.

Create a fault in the system by slowing down the wheel speed sensor or safely shorting out an inductive wheel speed sensor while you are applying the brakes. 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:

Red light turns on. The two gauges on the left that are held at 150psi drop to 60psi. Two gauges on right that also are held at 150psi rise up to 180psi with the needles fluctuating violently. Pressure is almost completely cut from left side and sent to right.

Catch an oscilloscope pattern when an ABS solenoid has actuated. What is the pin and name of the solenoid? 5 GN, How did you do it?

Oscilloscope turned to chop, channel 1 is connected to green 5. Brake pedal is pressed and left side wheel slowed by applying friction. Pump turns on. Oscilloscope reacts as shown in graph. There is back EMF of 24V.