Decleration

Scan Tools

Scan Tools are used to measure and diagnose your vehicle information, such as RPM, Ignition Timing, Injector Pulse width and readings from a number of sensors such as the 02 sensor, TPS (throttle positioning sensor), and (MAF) mass airflow sensor. It will also show certain switch position signals.

Using A Scan Tool

1. Plug the scan tool into the ECU, either under the dash or under the steering wheel. (Could be hidden)

2. Power On the Scan Tool. The display will come on, and after it communicates with the car's computer for a few seconds, it will display an OK message or a menu.

3. Navigate the menu to find the stored codes that the car's computer has stored into memory. These codes are collected overtime, and unless the vehicles battery has been disconnected, they should remain in memory. The scan tool will display these codes, along with basic data information about the code.

4. Write down the codes that are displayed and then research them. Automotive repair manuals will have a list of these codes and what they mean for that type of make or model. Many codes will start with a letter, followed by several numbers, such as F-233, and they are tripped by sensors that the computer monitors constantly. When these sensors determine something is wrong with the motor, they store the code in the computer so that the mechanic can determine the issue and repair it.

Example.

Here is a fault code for a 6 cylinder engine.

As you can see this is a 5 digit number, with a letter at the front. When I read the manual for this type of this vehicle, or go to the following website http://www.youfixcars.com/, I can see that the fault code is P0306- Cylinder 6 Misfire Detected. We now know that the 6th cylinder has a fault, and can now try to work out what the actual problem is. It could be a dirty spark plug, dirty distributor or any number of things. But at least now we know what the problem is. However the Scan Tool is preset to finding more priority faults first, so after the problem has been fixed, another isolated problem may still need to be attended to.

Scan Tool Observations

Find a Vehicle that will show you CAN system operation on a scan tool (such as the Range Rover)


Which Vehicle Are you using? Land Rover


Which Scan Tool are you using? Auto Boss


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


Primary Ignition, secondary Ignition, Multimeter, DSO, Engine Analyser


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


High


ABS/ TCS/ Engine Control/ EPS


Low


Tv, Windows, Body Control

CAN Multiplexing worksheet

CAN Waveform on an oscilloscope

1.1 Locate the Range Rover or other suitable vehicle with easily accessible CAN system twisted wires. Which vehicle do you have? (Year, Make, Model)
2001 Landrover

1.2 Locate a twisted wire pair. Describe where the wires are located. The Twisted Wire Pair were located inside the engine bay on the Hydraulic Control Unit

1.3 Record the waveform of one of the wires below. ("make sure your time is small enough so you dont have aliasing")

Colour of wire: Yellow

Time per division: 2 Seconds

Voltage per division: 0.5V

1.4 Record the waveform of the other wire.

Colour of wire: Black

Time Per Division: 20ms

Voltage per division: 1V

1.5 What is aliasing? Describe it: When a digital image is viewed, a reconstruction-also known as an interpolation-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 prealiasing and reconstruction aliasing postaliasing

1.6 How do you know these waveforms are not alisaling?

Because they are symmetrical when placed together, and this is what it should like.

1.7 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"?

1.8 In the 1.4 Waveform above, what is the main voltage on the line? 1.5V

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

1.9 Observe the signals in 1.3 and 1.4 with a voltmeter. Compare it with DC volts or AC volts setting . Which setting would tell you if the signal is switching. Explain. DC Would tell me if the signal is switching because I would get a straight line when it is either on, or off, while analogue will give me a curvy line.