blog 4

CAN MULTIPLEX WORKSHEET

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:

The pattern above is that of the L-can.to get an accurate pattern I had to put the voltage on 1v and the time on 5micro seconds.

YELLOW BLACK:

This pattern is H-CAN.I left the osilliscope settings the same and it was good enough to have a good patern.
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)

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:

got this one from:

http://amirs4825.blogspot.com/2010/11/controlled-area-network-board.html.

Stop lights:

Reverse light:

In all these patterns we used 1.0v for the H and the L CAN

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.

I was asked to locate the sensors and record their colours.
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.

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

blog 3 OSCILLOSCOPE PATTERNS on car

I did this on the 1zz engines.On the left side of the engine was all the terminals named to make it easier for us to get an oscilloscope reading without dameging the wires and sensor by back-probing all the time.Oscilloscope is a very efective way of checking sensors because it gives a good pattern and shows wats happening right now and can show changes when u play with throttle or fuel extra.

The first sensor on the list was ECT.
the voltage was 4.5-5v

I set the time on 5s and the voltage on 2v.The reason for changeing the time and voltage is to get a good and effective pattern.As seen in my other post we found that the ECT is a negative coefficient thermister.This means that the resistance is higher when the engine is cold.This would cause a high input signal at the ECU and as the car warms up the resistance will be lower therfor the voltage goes from 4.5-5v.There are some electrical faults that can make this sensor operate incorrectly like,if it has a bad earth,could have a faulty thermistor,dirty plug or a lose connection.The reason these things will make the sensor malfunction is.If we had a high resistance of 1kohm int the earth it would cause a high voltage output to the ecu.this will cause the car to run rich and use more fuel.If this would happen the pattern would have gone up faster than it is going up at the moment.
MAP SENSOR PATTERN
voltage range was 0.5-3.5v

To get an accurate pattern for this one I had the time on 1s and the voltage on 2v.
Where we can see the pattern at the bottom this is were I had it on idle,this was at 0.5v.The first wave is snap accelaration and this was at 3.5v.The second wave is cruising and as we can see it is a much wider wave than the other one the reason for this is that if u apply throttle wave goes up and wen take of goes down so at cruising u wil aply throttle slowely and get quite a wide wave.If there is a electrical fault like plug not in wires open or damaged dirty plug bad earth we will be able to see this in the pattern because the ecuwil get the wrong reading and this will cause the pattern to be inaccurate and unstable and not very consistant.These faults wwil also interfere with the car,could cause a lack of power use more fuel and have some flatspots.

THROTTLE POSITION SENSOR PATTERN
voltage range was 0.5-4.5v

My time and voltage was the same as the map where the time was on 1second and the voltage was on 2v.This was very good for me because made it nice and easy because i did not have to change nything on the oscilloscope.Again the bottom of the wave shows wide open throttle and as the wave climbs up it shows more throttle being added and at the top of the wave shows wide ope throttle.electrical faults is about the sanme but another fault is also when the tps is in the wrong posittion.If there is a fault with the  TPS the car wil be realy bad to drive could have slow reaction when applyin throttle could also have bad idle.At the worst case the car wont be able to drive at all.

INTAKE AIR TEMPERATURE SENSOR PATTERN

Again i had the time and voltage same.this patern is just a simpel pattern not as technical as the others.The highest point of the patterns is showing that it is cold and the lowest point of the pattern is showing that it is hot.The higher the voltage the more air is getting through the system.A dirty plug or a bad earth can cause this to go wrong and give a wrong voltage and ECU wont acuratly know if it is hot or cold.

RPM CAM

This is a very important pattern to have.If this pattern is not up to standards then it could cause the car to run badly or not at all.It is also very important to get the time and voltage right to get an accurate pattern.The time has to be alot faster to get it accurate because it on cam it very fast.

I had my time on 50ms for the reason that I explained that it has to be fast.My voltage just on 2v again just for the reason that I got a pattern out of it.In this pattern we can see alot of waves are consistantly the same but the middel part goes wider when we add more throttle we call this burn time.At idle it should be almost the same.when we have a bad sensor or bad earth this could cause the patern to be unstable and stil wil mean the car wil run badly and have a flat spot.

RPM CRANK

I had to use 5v for voltage and 2ms for time.This pattern works a bit differently if you add throttle the whole waveform wil change together.Top of the waveform is when it is at peak point under acceleration.

All of these patterns are important to give a good drive for the car and the driver.This is a very good and efective way of checkin all the sensors and also a good wau for fault finding just because of the reason that a gives a good live data.

blog 2 INPUT SENSORS AND ACTUATORS ON CAR

There is alot of sensors and actuators in a car more in some than in others but all of them mostly inportant if one is faulty it will be noticed by driver some differint ways than others could be by performance economical alot of different ways.I pack probed a fuel injector with a pin and got a voltage reading of 14.1v.It is important to get a good voltage at the injector because if there is a bad voltage then that injector wont work properly and car will lack performance and could have bad fuel economy because ecu will be makin richer addin fuel to make it run right.A bad voltage could be cause by a bad earth or resistance build up in control circuit.
I was asked to draw a diagram of the fuel injectors.

Refrence voltage at TPS
The reason for the reference voltage at the TPS is to let the ECU know wat is happening how open throttle is so ecu knows how much fuel to add.Thing like bad earth and open circuit is things that could cause the reference voltage to be low.
To check the earth at TPS I had to back probe the ground wire wiv a pin and record voltage. I did this and got a result of 0.03v,this shows that there is a good earth.
I got an input wire again I back probed the wire i recorded the voltage with ignition on and got a result of 0.38v I tested this at half open throttle and got a result of:2.23v and at wide open throttle i got a result of:3.78v
A tps sensor works by using a input voltage and a variable resistor around a shaft to send a output voltage from .5-4.5v depending on relationship between shaft and variable resistor.The ECU should usually get a voltage of 0.5v at idle from the sensor to 4.5v at wide open throttle.There are some things that can prevent the tps from sending the correct voltage like faulty earth,faulty input and also faulty tps.I was asked to draw a circuit diagram

The picture above is the circuit I had to draw.The reason there is a output needed for the ECU to properly run the engine is because the ECU needs to adjust all the sensor to what the driver is doing for example:when the driver is driving a wide open throttle the car needs more fuel therefore the injectors needs to spray more fuel.

ENGINE COOLANT TEMPERATURE SENSOR (ECT)

The ECT is usally located where the radiator pipes meet up but this differs with different maufactures.I was asked to measure the voltage at the ECT I did this by back-probing the wire then using a multymeter on DC volts and got a result of 3.5v.This reading was taken with ignition on engine not running so it is at normal temperature.After this I started the engine and let it run for a bit and got a result of 1.1v.This shows me that this is a good ECT because as the temperature increases the voltage decreases because it is a negative coefficient.The ect works with a set resistance in the ecu that make the use able to adjust sensor to the engine.The ect voltage can also affect the fuel injection because a higher output from the ect at cold tempreature gives a higher voltage to the ecu causing it to ground injectors for longer.A faulty thermister or a faulty earth will give the ecu the wrong voltage which could cause the car to run badly.I back-probed the black wire which is earth and measured voltage with multimeter and got a result of 0.1mv this result shows sensor has a good earth.A lose connection could cause a bad earth.

above is a a ect circuit diagram and at the bottom is the actual ECT

RPM SENSOR

When testing this we put the multimeter on AC volts instead of DC.We test it by back-probeing a signal wire.Started the car and recorded my result and I got a result of 90mv at idle.I increased the engine RPM to 2500 RPM and got a result of 200mv.I put the multimeter on DC volts and got a result of 1.2v at idle and after increasing the RPM to 2500 again I got a result of 16mv.I was then asked to set me meter to read Hz and at idle I got a result of 5KHz and at 2500RPM my result was 7.5KHz.This results shows me that using AC voltage is the best way to see if the sensor is working properly and is also acurate reading.The 4a-fe engine I was using had a hall effect type rpm sensor.This type of sensor works with a magnet and a plate plate pases through the magnet then it grounds and sends a voltage out the sensor wire.It is good to use diferent functions of the meter to get acurate results it gives us an idea of what the patern would look like because we know the size and power amount of it.

I got a circuit diagram of this sensor of electro-circuit.com

The picture at the botom is a hall effect RPM sensor

The arrow poimts to the magnet and can also see it has 3 wires going to it and in the middel we can see the 4 poles.

MAP OR MAF SENSORS

We had a choice between MAP or MAF sensor I used the MAP sensor because the engine I did my work on used a MAP.
I backprobed the sensor to get a voltage reading.I did this and with ignition on car not running I got a result of 1.8v.I started the engine and let idle for a bit and got a result of 0.5v.After this a gave it a quick acceleration and got a result of 1.8v.The map sensor works with presure and measures it and sends it to ECU with the signal wire and the ECU adjust the engine to that result by using other sensors.the readings i got was correct because it went up when short acceleration because there is more preasure.bad conection or pipe not on could give ecu bad reading

INTAKE AIR TEMPERATURE SENSOR

I bak-probedthe sensor and turn the ignition on and measured voltage and got a result of 3.3v.This reading is 0.2v less than that of the ect.This show that the iat is hotter than the ect.The IAT works by measuring the temp goin through the intake and sending it to the ecu.The IAT voltage effects the ecu for fuel injection in the same way as the ect if it is wrong the injotor time would be wrong.The sensor signal sends out a higher signal if the tem rises.A bad connection or bad earth can cause the incorect signal for the ECU

CAMSHAFT POSITION SENSOR

With the following sensor i did not go to deep into it just got the 4 differint readings with a multimeter.

DCvolts:19.5mv
ACvolts 1.2v
hertz:0.09kz
%duty cycly:14.1%
These results showed me that the best way to measure this was with duty cycle

blog 2 on car flash codes

I did this exersice on the 4a-fe engine could b in a 1992 toyota corolla.This is used to find faults with jus ur check engine light and a jumper wire.I used a jumper wire with a fuse on it to make sure i dont blow anything.To do this you need the workshop manual to get fault codes if there is not a manual avalibale it is posible to find them on internet by puting in the engine name in google for example for this we would say 4a-fe fault codes.I used the jumper wire to jump from E1 to TE1.This may be differint for differint manufacturers.
I got my tutor to create a fault in the engine after i hooked up my jumper wire.I turned ignition on and the check egine light came on,it flashed twice then after a while flashed four times this makes the code 24.Checked the workshop manual I found that the code was for the IAT.Next code was 31 wich is for vacum.I did a visual inspection and found that the plugs were unpluged.The visual inspection was realy easy because after getting the fault codes i knew exactly were to look.I repaired the fault by pluging it back in and starting car to make sure all is well.after repairin fault I had to clear codes I did this by turning kill switch on and of in normal car just remove battery terminal for a few seconds.The faults i found would efect the engine in a big way by having a bad idle,car would be lean and could also have a constant flatspot.When finding a fault like this it is important to check the wires and the cause for the problem and also wat can be done to prevent this from happening again.
This is a realy quick and effective way of checking faults in a car and can also be done on side of the road if neccesary.

blog one off car

THROTTLE POSITION SENSOR

There is two types of tps sensors known as the potentiometer and switching type

first type i tested was the potentiometer:
this can also be caled a veriaing type or linere type.
It is a three terminal resistor the wiper movin part is usaly the midle terminal of the three.
I got this from wikipedia.org

I conected a power supply to the sensor and tested the voltage at different throttle angles
and got a result of:

throttle angle:                                                            voltage output
0                                                                                     336mv
25                                                                                     0.9v
45                                                                                      1.6v
60                                                                                      2.5v
75                                                                                      3.2v
90                                                                                      3.89v

all angle is in degrees and the voltage output readings is for main if it was for the idle it would of been 100mv at all the angles.

The picture above is of potentiometer

Next I tested the switching type
is either on or of unlike the potentiometer
it switches at 15degrees to O.L no continuity
It switches at 75degrees from O.L to 0.55v
This is at wide open throttle

Air flow/mass sensors(MAF)
Hot wire type
I measured voltage when i first powerd up the sensor without passing air over sensor
got result of 0.32v
when i pased air over it I got a result of 2.6v
This result was within manufacturer specs

Next was the vane type
Hooked up to a power supply and recorded the voltage change with the differint angles:

vane angle                                                  voltage out
0%                                                                0.84v
25%                                                              2.14v
45%                                                              3.40v
65%                                                              4.40v
85%                                                              5.20v
100%                                                            5.80v

I checked the part number used google typed it in and it came up with all the specs and I found it was within manufacturer specs

The mass airflow sensor converts the amount of air drawn into engine into a voltage signal.The vane airflow meter provides the ECM with an accurate mesurement of load placed on engine.
vane type consist of the following:

• measuring plate
• compensation plate
• return spring
• potentiometer
• bypass air passage
• idle adjusting screw
• fuel pump switch

        intake air temp sensor
got this info from http://www.autoshop101.com/forms/h34.pdf
If any of these components are broken or faulty the air flow meter wont be able to work as it should.


Thermistor:
i took a bole filled with water then put thermister in on piece of wire and heated water up and recorded recistance as water heats up.

WATER TEMPERATURE                                                    RESISTANCE
35                                                                                           1.53kohm
40                                                                                           1.46kohm
45                                                                                           1.02kohm
50                                                                                           0.89kohm
60                                                                                           0.70kohm
70                                                                                           0.52kohm
75                                                                                           0.41kohm
80                                                                                           0.34kohm

All the temperature was measure in degrees.A thermistor is a type of resitor and resistance changes alot with the change of temperature.As temp goes up the resistance goes down.This makes it a negative tempreture coefficent,If the resistance would of increased with the temprerature increasin it woud be called positive temprerature coefficent.

KNOCK SENSOR:

I conected a knock sensor to an oscolloscope and tapped the end to get a waveform

time was on 830.0us and voltage on 1200mv
The knock sensor has a crystal in it that when it gets tapped it jumps around and creates a voltage therefor wee do not need to ad a voltage supply to it.In this photo the middel is called the 0 line.I had some trouble to get the setting on the osciliscope right but with the tutors help i got it perfectly right and the photo shows the outcome i got.