CAN

Locate the Range Rover or other suitable vehicle with easily accessible CAN system twisted wires. Which vehicle do you have? ( Year, make, and model).

Land Rover 2003

Locate a twisted wire pair. Describe where the wires are located:

It is located under the bonnet on the passengers side and connected to the ABS Control Unit

Record the waveform of one of the wires below: (Make sure your time is small enough so you don't have "aliasing".)


Colour of wire: Yellow
Time per division: 2 Seconds
Voltage per division: 0.5V


Record the waveform of the other wire in the twisted pair.

Colour of wire: Black
Time Per Division: 20ms
Voltage per division: 1V

What is aliasing? Describe it: When an image is viewed, a reconstruction is performed by a display, and by the eyes and the brain. If the resolution is too low, the reconstructed image will differ from the original image, and an alias is seen. Aliasing can be caused either by the sampling stage or the reconstruction stage; these may be distinguished by calling sampling aliasing pre-aliasing and reconstruction aliasing post-aliasing

How do you know these waveforms are not "aliasing"?

They are clear and easy to read

In the 1.3 waveform above, what is the main voltage on the line?

2.5V

What is the other voltage on the line, when the voltage is pulled up or down to "talk"?

1.5V

1.8 In the 1.4 waveform above, what is the main voltage on the line?

2.5V

What is the voltage on the line, when the voltage is pulled up or down to "talk"?

3.5V

Observe the signals in 1.3 and 1.4 above with a voltmeter. Compare it with DC volts or AC volts setting. Which setting would tell you if the signal is swtching. Explain:

YellowBrown: DC = 2.352V and AC = 0.23V

YellowBlack: DC = 0V and AC = 0.002V

This observation shows how they are switching on and off.

Find a vehicle that will show CAN system operation an a scan tool (such as the Range Rover).

Which vehicle are you using?

Land Rover 2003

Which scan tool are you using?

Autoboss

What different functions are available on the scan tool to examine the CAN system?

Primary ignition
Secondary ignition
Multimeter
DSO
Auto DSO
Engine Analyzer
Setup

List the different systems that are controlled by CAN? (note which are high speed and which are low speed)

High - ABS , TSC, ECU, TCU, ESP.

Low - TV, Windows, Body Control Unit, Central Door Locking, Cooling Fans, Alarm, Steering, Seats and Fuel Pump.