We only had one car new enough to this experiment on.The car we used was a 2006-2008 range rover(not to sure ont the age of this car).Can systems use crossed wires to have less resistance to the modules.On my worksheet I was asked to locate these wires.I did this and found it was by the ABS module.I was also asked to put an oscilliscope on one of them to get a pattern.I did this.
YELLOW BROWN:
YELLOW BLACK:
The next question on my worksheet was:what is aliasing is? I had no idea so I googled it and got this result:Aliasing is jaggering,stairstep effect on curved or diagonal lines that are reproduced in low resolution as on a computer prinstious or division.I had to ask around a bit and found that basically it means it is not clear.Both the patterns are good and not aliasing.
In the L-CAN the main voltage on the line is 2.5v.The other voltage is 1.4v.In the H-CAN has a main voltage of 2.5v and another voltage of 3.5v.this means voltage goes up to talk and on L-CAN voltage goes down.The reason for this is because the H-CAN more important.
compare with dc volts or ac volt setting:
2.6v
DC 2.3v
AC 0.1mv
SCAN TOOL:
we were asked to use a scan tool on this vechile and observe what is happening and wat we can do with the scan tool.
There are some different functions to examine can system:
fault codes
actual values all selected
actual values manual selection
actuations
There was alot of different systems that are controlled on can:
low speed:
lights
seats
central locking
windows
washer fluid
aircon
wiper
radio
high speed:
Air bags
ABS
Traction controll
Instrument cluster
The reason we have a high speed is because of the things that are important we do not want the airbags to be to slow to protect us in a crash.
Doin this exirsice was awsome because you can move everything with the scantool like seats turn on radio etc.
The picture we got here is of a wiring diagram of the range rover high speed can.
This is the fast can diagram.Got this fromhttp://ttec4826-vlad.blogspot.com/2011/06/can-multyplexing-worksheet.html
Had to locate a system that goes to sleap after a short time.I found the can system does this.
voltage when the system is awake is 2.5v-2.6v.The voltage when system is asleep is 0.2mv.The voltage change on the yellow brown wire.Things like keyless entry is what wakes up the system when it is in sleep mode.
HONDA MULTIPLEX SYSTEM
Picture above is the board we used to do the exirsices on.First I will just have a quick run down on what is happening here.The two boxes are our nodes.The four round objects are our four windows all of them has two relays under them as we can see.left bottom corner we hav our central locking with its two relays on the right of it.on the right of that we have our drivers door node this is what drivers use to open windows and lock the doors.The switch above the drivers door node is the fault code switch,on the left of that we have our central locking switch.
This is the wireing diagram that I used to do the experiments.Mainly had to use it to find colours and find the plugs.MCU door=A15 to MCU (drivers) A2 is a brown wire.MCU (drivers) B1 to MCU(pasengers) B9 is a pink wire.
Earths and voltage supply lines between nodes:
Multiplex controll unit (door,drivers and pasenger)runs a pink wire from power to A1(door) A12(drivers) A24 (passengers)
Earths and voltage supply lines between nodes:
Multiplex controll unit (door,drivers and pasenger)runs a pink wire from power to A1(door) A12(drivers) A24 (passengers)
We were told that there has to be a fault created on the board so we got our tutor vjay to do this.After he did this we checked everything and found that only the driver door's window was working.The central locking was also not working.This happens when we have a break in the comunication lines only reason that one window was working is because there is not a node in between.Next step was to use my diagram to see what went wrong and what it can posibly be.It ended up being wat i thaught it would be.Because of the break in the line the comunication lines are not connecting with the nodes.I was sure that this was the fault after i did my fault test and it beeped ones.we are not alowed to do contenuity test because indusein current into system can cause it to break and be faulty not working like it should.We tested voltage for brown wire to unit and got a voltage of 0.2v so there is a high resistance so it is an open circuit.voltage with groun is stil 8.5v because they are still comunicatting.Pink wire was good.voltage flowing both ways so I got 8.3v on both sides with a 0.2v drop in the middle.
Only way to diagnose this is with a voltage drop test after doing this I got a result of 0.2v so we have resistance.
CONTROLLED AREA NETWORK
This is the board we had to use.The worksheet asked to use an ocilloscope to get pattern for the H-CAN and the L-CAN.On this board the yellow wire is for the L-CAN and the blue wire is for the H-CAN
I did this in dual pattern so i could capture and compare both these (L-CAN and H-CAN)
Top channel A this is the H-can wich obviously means that bottom is channel B the L-CAN.
Voltage we used here was !v for both and 25micro seconds.They both have the same base voltage this is why they are over eachother.
I was told to capture the paterns of the folowing inputs inputs:
Right indicator
Left indicator
Rear wiper
Stop lights
Fuel pump
Reverse lights
Right indicator
Left indicator
Rear wiper
Stop lights
Fuel pump
Reverse lights
Right indicator:
Left indicator:
Stop lights:
Reverse light:
with the time on 25 micro seconds.all aptterns are differnt because the have to send differint signals that has to be identified so cant be same.
ABS DEMONSTRATOR:
We were given a wireing diagram to find all ecu pins and asked to get and oscilloscope pattern for all the wheels on the demonstrators
Left front-ecu pin 4 and 5
Left rear-ecu pin 7 and 9
right front-ecu pin 11 and 21
right rear-ecu pin 24 and 26
Above is the wiring diagram I was given.
On work sheet it asked wat type of wheel speed sensor the unit uses.After a good look I found that it was a magnetc inductive type.This type uses a passing magnet to induse current into the windings.
Front right:
Front Left:
Right Rear:
Left Rear:
got all the waveforms above from:http://amirs4825.blogspot.com/2010/11/abs-demonstrators.html
These all look the same but they are not the right side has higher voltage than the left side.
left front: 3.593v
left rear: 2.695v
right front: 4.473v
right rear: 5.141v
This is all the voltages I got with them in action and spinning.
Using a multimeter wont be as acurate as using an oscillioscope because it alot more acurate and does not just give you a reading but also gives us a pattern that can show us the peak voltage frequncy ect.
We Had to work through our work sheets so we did.The only reason we did the demonstrators first is because everyone wants to use the demonstrator so just wanted to get out f way
There are some things that can cause an ecu to break.Welding on the car without disconecting the battery can cause this aswell as water aroun the ecu and ecu not properly seald also bad one.ECU damage can cause alot of things when there is a lack of comunication one of them is the ABS stop workin.
We were givin a sheet with all the abs system layout and the components on it.We were asked to name them.
1=brake disc
2=speed sensor
3=tooth wheel
4=modulator
5=master cylinder
6=caliper
7=brake booster
We were given a wiring diagram with some tasks.
Front right: -white +black
Front left: -green +red
Rear left: -pink +blue
Rear right -brown +yellow
ABS wheel sensors has braded wire,the reason for this is to sheild other wires from frequency and for interferance.
there is a list of fuses in the abs circuit:
warning light fuse
stop light fuse
battery fuse
ignition fuse
abs fuse
battery main fuse
using the wiring diagram again i was told to identify the earths for abs wire colours and pin numbers
pin-10 white black
pin-7 white black
I was told to identify the solenoids control wich wheel cylinder:
Front right wheel
pin number:2B and 6B
wire colour:red white and red green
Front left wheel:
pin number:3B and 7B
wire colour:blue red and blue white
rear left wheel:
pin number:1B and 5B
wire colour:Brown red and brown white
rear right wheel:
pin number:4B and 8B
wire colour:Green black and green yellow
SCAN TOOL EXERSICES
The first thing we could realy do was to work with the ABS live data.
Front right wheel speed sensor
front left wheel speed sensor
rear left wheel speed sensor
rear right wheel speed sensor
brake light switch
We were asked to do the electronic transmission on this.
We were asked to identify what everything means:
PCM:powertrain control module
TCC:Torque converter clutch
TPS:Throttle position sensor
ECT:Engine coolant temperature
VSS:Vehicle speed sensor
PSA:transmission range fluid presure switch asembly
TTS:transmission temp sensor
We were asked to answer some more questions using the following diagram
Was aked which solenoid are on when the vehicle is shifted ibto drive and starts in first gear:
2nd and OD
which solenoids are on when the vehicle automaticaly shifts into second gear:
OD and LR
which solenoids are on when the vehicle automatically shifts into third gear:
LR and 2nd
which solenoids are on when this vehicle automatically shifts into fourthb gear:
LR and UD
It took me a while to get the hang of using this chart but i did this after a bit of help from vjay our tutor.
2nd and OD
which solenoids are on when the vehicle automaticaly shifts into second gear:
OD and LR
which solenoids are on when the vehicle automatically shifts into third gear:
LR and 2nd
which solenoids are on when this vehicle automatically shifts into fourthb gear:
LR and UD
It took me a while to get the hang of using this chart but i did this after a bit of help from vjay our tutor.
I was asked to use the repair info and pick two codes.
code 58
transmission fluid temoerature
to repair this fault I can check for voltage drop at the signal wire and compare the signal voltage to the manufacturers spec.
code 82
1-2 shift solenoid circuit faulty
FUEL PREASURE AND FLOW
This test was done on a 4a-fe.Before these test can be caried out it is inportant to know where the fire extinguishers are i only found one wich was located on the lefthandside of the door when you are entering the room.The presure specifications on this engine was 38-44psi.When i caried out these test i used psi for all my pressure readings.The first test i did was to measure the fuel presure with engine at idling and got a result of 36 psi the engine had a gauge for this so just had to read the gauge to get a result.Next test was to use a speacial clamp given to me to clamp the fuel return for a short while and get the reading.I got a result of 89psi.My next test was to disconect the wacuum line going to fuel regulator and record reading.I got a result of 45psi.I had to turn the engine of and watch the reading after 5 minutes I got a result of 40psi.It is inportant to know the vehicles fuel presure because it can give you a indication of what is wrong with your car and if your car is smoking it mitght be because it is running rich then you will be able to check this if you find owt your fuel preasure.When a car has got low fuel preasure it could have a leak somewhere in the fuel system that is causing this.When the car has got high fuel preasure it could be caused by a block in the fuel lines and this could also cause it to leak because it is getting to much presure and could cause it to run rich.When the car has a faulty fuel regulator this could be caused be diferent things depending on what is wrong with the regulator.If the regulator is stuck open it wil have a low fuel preasure and have same symptons and when stuck closed it will have a high fuel preasure.When the car has low fuel flow it can run a bit lean and feel like there is a lack of power this could be caused by a dirty fuel filter or a faulty fuel regulator
transmission fluid temoerature
to repair this fault I can check for voltage drop at the signal wire and compare the signal voltage to the manufacturers spec.
code 82
1-2 shift solenoid circuit faulty
FUEL PREASURE AND FLOW
This test was done on a 4a-fe.Before these test can be caried out it is inportant to know where the fire extinguishers are i only found one wich was located on the lefthandside of the door when you are entering the room.The presure specifications on this engine was 38-44psi.When i caried out these test i used psi for all my pressure readings.The first test i did was to measure the fuel presure with engine at idling and got a result of 36 psi the engine had a gauge for this so just had to read the gauge to get a result.Next test was to use a speacial clamp given to me to clamp the fuel return for a short while and get the reading.I got a result of 89psi.My next test was to disconect the wacuum line going to fuel regulator and record reading.I got a result of 45psi.I had to turn the engine of and watch the reading after 5 minutes I got a result of 40psi.It is inportant to know the vehicles fuel presure because it can give you a indication of what is wrong with your car and if your car is smoking it mitght be because it is running rich then you will be able to check this if you find owt your fuel preasure.When a car has got low fuel preasure it could have a leak somewhere in the fuel system that is causing this.When the car has got high fuel preasure it could be caused by a block in the fuel lines and this could also cause it to leak because it is getting to much presure and could cause it to run rich.When the car has a faulty fuel regulator this could be caused be diferent things depending on what is wrong with the regulator.If the regulator is stuck open it wil have a low fuel preasure and have same symptons and when stuck closed it will have a high fuel preasure.When the car has low fuel flow it can run a bit lean and feel like there is a lack of power this could be caused by a dirty fuel filter or a faulty fuel regulator
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