CAN-Multiplexing worksheet

We used A 2008 Range Rover to do the next tests on.First thing we had to do was locate the twisted wire pair.I did this,and it was located by the ABS module loom.The wires were yellow brown and yellow black.I was asked to record the waveform of one of the wires

yellow brown:

This is the L-Can.The time per division was 5 micro seconds and the voltage per division was 1v.

Yellow black:

This is the H-CAN.I had a time per division of 5 micro seconds and a voltage per division of 1v.

Aliasing is jaggering,stairstep effect on curved or diagonal lines that are reproduced in low resolution as on a computer prinstious or division.This is how I got it on the dictonairy but it basically means that it is not clear.These waveforms are not aliasing because they are clear we have no trouble seeing and identifying them.

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 observation:

Stil using same vehicle.With a autoboss scan tool.

Different functions to examine can system:

controll unit version

fault codes

actual values(all selected)

actual values(manual selection)

actuations

different systems controled on can:

lights-low speed

wiper-low speed

washer fluid-low speed

central locking-low speed

airbag-high speed 

window-low speed

instrement cluster-high speed

ABS-high speed

mirrors-low speed

aircon-low speed

Above is the wiring diagram for the range rover fast CAN

Above is the wiring diagram for the range rover low speed CAN.

Got the pictures above from:

http://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.

We were givin a honda multiplex board:

This is a picture of the board we used.The two white boxes in middle of the board is the nodes.the round white things are for the windows and their relays under them.The thing on the left at the bottom of board is the centralocking and it relays next to it.The big black thing at the bottom is the driver door node.This is what drivers use to open the windows and lock doors.The switch on top of it is the fault code switch and on the left of that one is the switch for the centralocking.

I used the wiring diagram above to identify the plugs and wire colours for communication lines between nodes:
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 asked Scott to create a fault in the unit:
When this fault was created in this unit the drivers window was working but none of the other windows were working.The centralocking was also not working.This means that the comunication line to the units are not operating properly.Driver side was working because it does not go to nodes first it goes straight to window instead.
Next I had to use the wiring diagram to analyze the fault:
The comminucation lines are not connecting with the nodes so the nodes do not work.This could be because there is a break in the line.
I had to put the system in test mode.I did this and it came up with one short beep.The fault that comes up is the same as what I diagnosed it with before.
We cant do a continuity test because you can break it if you induse current into it when trying to test it.Therefore you are never aloud to use a test light on this circuit because it has almost no current in it.
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.
The door unit has no inputs to the drivers window because there is a break in the comunication line to drivers side.Has beep at the interior light so it is working.Unit not sending input to the nodes.
To diagnose I have to do a voltage drop test between A15 and A2.I did this and got a result of 8.7v at A15 and 8.5 at A2 so there is a voltage drop of 0.2v.this shows high resistance.
We were asked to put the system into sleap mode.We could not do this because the board we used was not wired up to do so yet.Sleap mode is used so the system does not flaten the batery when you turn the ignition of.

controlled area network board

We were givin a can system board with a list of things to do.

The picture above is a picture of the bored we were givin to use
Used an oscilloscope to capture the full pattern of the H-CAN and the L-CAN.The yellow wire is for the L-CAN and the blue wire is for the H-CAN.

I had to capture the data patern where it starts and stops.I did this by hoocking up the one to the blue wire from the H-CAN and hoock the other channel of the oscilloscope to the yellow wire for the L-CAN.

The top line is channel A.This channel is hoocked up to the blue wire H-CAN.The bottom line is channel B.This channel is hoocked up to the yellow wire wich is the L-CAN.The voltage division was 1.0v for both the H-CAN and the L-CAN. with the time on 25micro seconds.The relationship between the two patterns is  the base voltage is same thats why they are the same over eachother.The voltage is 2.5v.As the H-CAN is switche above 2.5v the L-CAN mocks this switching with an equal yet opposite voltage from the base voltage.

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

Stoplights

reverse light

In all the patterns above the voltage division was 1.0v for the H-CAN and 1.0v for the L-CAN and the time was on 25 micro seconds.This is the same as that of the original can.As we can see all the paterns shown above are alot differnt than the origal CAN the reason for this is because they all have to send out a different signal to know what has to turn on and when it has to turn on.The code is the amount of zeros.This changes with the different patterns.

rear wipers:

fuel pump:

the pictures above I got from:
http://amirs4825.blogspot.com/2010/11/controlled-area-network-board.html.

the reason I took his is because I didnt take picture when I did it

I used the Wiring diagram above to identify the inputs and outputs relays or transistors and wire pins and colours for the right hand indicator.

Right hand indicator indicator= 7-6
input voltage pin 7- tock I pin6 then output signal from RB2/can tx and Rb3/canRx to pins 1  and 2  then the output pins 7 CAN-H and 6 CANL to Ic4 and Can-L to can receiver IC5 and then the output pins TxD to TXCAN/TXRXCAN and RXD to RXCAN/NC and from the outputs GP4/REF and then to OPTOC coupling which switches the transistor which responds to light from the LED which then switches another transistor on which then finally switches the right hand indicator on.That is the whole proces of how the right hand indicator turns on did this by folowing the diagrame shown above.
Using the diagram I had to identify both the voltage regulator that resemble the one we built in ttec4824.They are similar because they change the voltage from a 12v supply to a 5v.Pin 1 and 2 input U2 7805 Pin 14 VDD.

ABS wheel speed sensors

I did the folowing tests on a daihatsu.The wheel sensor on this vehicle was a analogue type.I found that this was a analogueb type sensor because it had 2 wires goin to it and a digital type usaly has 3 wires sometimes more.I used the back wheel sensor because I coul not get to the front ones plug so was not able to see the amount of wires going to it.I was asked to measure the air gap for each wheel sensor.I could not do this because ther was a plate in the way and I did not have any tools to remove this.

This is an example of the type sensor the  vehicle I used had.
http://www.google.co.nz/imgres

I used a oscilloscope to get the patern for the wheel sensor.

This is A analogue pattern as I talked about before.
had it at 0.5v and 20ms

Using a scan tool

We used a scan tool on a 1997 mitsibitchi galant.The first thing we did was to go on to the ABS life data and record all the sensors:

Front right wheel speed sensor
front left wheel speed sensor
rear left wheel speed sensor
rear right wheel speed sensor
brake light switch

After doing this I went to the actuator test screen and listed the tested components.
solenoid valve 1
solenoid valve 2
solenoid valve 3

Next thing we did on this car was the electronic transmission
First we had to know 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

I used the workshop manual to get all the sensors and actuators.

I also got the wiring diagram for the system.

Got the pictures above from:
http://amirs4825.blogspot.com/2010/11/electronic-transmissions-and-scan-tools.html

I used the folowing diagram to answer some question that was asked.

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

I got all these results by looking on the chart showen above
If there is a shift solenoid malfunction and vehicle is stuck in a high gear it would want to stall and when stuck in a lower gear like first wont be able to go fast probably only about 60kmph in most cars.

I used the repair information to 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.

to diagnose this fault I can check all the earths to make sure I have a good earth and see if I hav a high resistance.

ABS Relays

The name of the relay that powers up the ABS ECU.I got it on the wiring diagram.
k39(protection relay)

ABS pump relay:
k100(pump motor relay)

ABS HCU solenoids relay:
y22(hydraulic modulator relay)

ECU pin number for wire that gives power to ABS ECU:
26(A)

ECU pin number for wire that controls relay for ABS:
1(B)

ECU pin number for wire that gives power to the ABS pump:
8(E)

ECU pin number for the wire that controls ABS pump relay:
2(H)

I got all the relay names and ECU pin number by using the wiring diagram and folowing it.

I used a oscilloscope to capture the waveform that shows both the controll circuit change and power switching.

I got this picture from:http://amirs4825.blogspot.com/2010/11/abs-relays.html

channel 1(the bottom one) is the controll circuit and channel 2(the top one) is the switching circuit.Point A is when the switching circuit turns on and goes from 0v to 12v.B is when the switch is open,this is when the switching circuit is open.Point c is when the control circuit has collapsed we ca also see a voltage spike at this point.Point E and D is when the pump has been turned on and off.

ABS pump relay waveform:
 had to get waveform of control circuit changes when relay turns on and the power switching on to power on the ABS pump.

To get this waveform I had to conect HC11 to power 85 and hotwire 30 shows the top one and 85 is the bottom one.On chanel B(the top one.)were it goes up is were its turned on and the top part from corner to corner shows that ECU is earth trigerd.Then at the second time when it goes up again is when the key is turned off.Then at the bottom one where it goes up is when ABS pump spiking.When down again is when signal switched.

ABS self test:
To make sure all the components in the ABS system are workin it has to do a selftest,it does this test when we turn the ignition on.It has a 12v supply.The ABS control module checks most of the components in the circuit exept for the components it can not check like the wheel speed sensors wich cannot be checked unless the car is moving.If the ABS controll module does not triger the failsafe relay the ABS light on the dash will not go of.This wil indicate that the module has found a fault in the ABS system.

Create a fault:
I did this by slowing down a wheel speed sensor while aplying the brakes.I did this by using a piece of plastic pipe and pressing on wheel while braking.The modulator can see this because one wheel slowin down faster than the rest of them so senses tha it is going to lock up.It stops this from hapenning by opening the inlet valve with a solenoid so there is no more presure being applied.

ABS solenoid actuated:


On this diagram we can see all the pin number and solenoid names.for example were it says solenoid LF means lef front solenoid then the wire that goes down to circile tha say 1B is the pin number for that solenoid.
Left front solenoid:
pin:1B
right front solenoid:
pin:1C
Left rear:
pin:1D
right rear:
pin:1A

I got the waveform for this on oscilloscope for the left front solenoid.

It is a solenoid therefore it looks like an injectors waveform they also share some of the same qaulitys.

ABS Demonstrators

I used the wiring diagram above to find the wheel speed sensor pinout connections to the ecu.

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

The type of speed sensor in this ABS unit is a magnetic inductor type sensor.It works with a passing magnet induses current through the windings.It has a magnet that creates a magnetic field.
Iused a tech tronic oscilloscope for the following tasks.

I had to get the osciliscope waveform for each of thewheel speed sensors.
The first sensor I did was the front right

front right

front left:

left rear:

right rear:

I got all the waveforms above from:http://amirs4825.blogspot.com/2010/11/abs-demonstrators.html
The waveforms arnt all the same,the left side looks identical and the right side also looks identical but the right side voltage is alot higher than the left side.

with wheel speed sensor spinning I measured the ac volts and got result of:

left front: 3.593v
left rear: 2.695v
right front: 4.473v
right rear: 5.141v

A multimeter wont be as acurate as a oscilloscope.The advantages of using a oscilloscope is that an oscilloscope shows a patter/waveform,this waveform can show you the maximum voltage outputs,peak to peak voltage and frequency ect.These waveforms allow you to visually see any faults in the circuit being tested,can aloso show changes in the circuit.If you are able to read these patterns it makes it alot more simple and acurate to diagnose fault vurther than using a multimeter.