Electronic Transmission

Electronic Transmission
On Rex's Honda Accord Euro 2010

PCM=Powertrain control module
TCC=Torque converter clutch
TPS=Throttle position switch
ECT=Engine coolant temperature sensor
VSS=Vehicle speed sensor
RSA=Transmission Range fluid pressure switch
TTS=Transmission temperature sensor

Block diagram
Sensors:
Gear selection switches
Economy/Power switch
TPS
VSS
Air conditioner switch
Engine Speed sensor
Transmission temp. sensor

These sensors go to the PCM which then actuates these actuators:
Shift solenoid and control solenoids.
Pressure control solenoid
Torque converter clutch solenoid

Electronic transmission wiring diagram


Trouble codes
Code 58-59
Trouble codes 58-59 shows that there is a fault with the transmission fluid temp sensor. (TFT)

Code 67
TCC fault, this shows that there is a solenoid circuit fault.

Diagnosis
Problem testing
Problem 1.
You can take out the sensor and test it separetlyby putting it in cold water attched to an ohmeter. As you slowly warm the water the resistance would decrease. If this doesnt decrease in resistance, or not to within specs than it is faulty.

Problem 2.
You would test the TCC by volt dropping each solenoid individually till you find the faulty one. You can volt drop by having the negative to earth and the positive on the positive side of the solenoid.


Using the scan tool to watch the solenoids at work.
If none of the solenoids would turn on in Rex's car then he would be stuck in 4th gear, as this is the gear with all solenoids off. I think this is unusual as I don't think that the car would be able to limp home in 4th gear especially if it had to stop and take off again. Most cars all off gear would be 2nd or maybe 3rd.
The shift lock is the little hook that stops the car being started in any other gear apart from park, this is so the car doesn't immediately take off when you start the car.

We were unable to view the torque converter clutch on the scan tool. So I'm unable to to tell you how the torque convertor was effected by the gear changes.

When the brake is applied the torque convertor disconnects from the 1:1 ratio that it was using at cruising speeds. It must use the 1:1 at high speeds otherwise the transmission will overheat and it also helps with fuel economy. So as the brake is applied the car is going to be at slower speeds which then needs the torque convertor to activate and act like a clutch to give smooth shifts.

CAN-Multiplexing

Working on the Range Rover CAN bus.
We found the twisted wire pair on the ABS control module.

1st waveform
Wire colour: yellow-brown
Main voltage: o.5V
Talking voltage: 2.5V

2nd waveform
Wire colour: yellow-black
Main voltage: 1.70V
Talking voltage: 0.3V

When tested with a mulitmeter on the AC setting the readings were 5V and 4.5V.
Compared to the above DC setting the AC is not very accurate as it can't tell you if the signal is switching. It reads the wires both front and back so to say so it doesn't know the difference when it is switched.

Aliasing is when you have a jagged effect of a smooth line or curve. Looks like zigzags on an oscilliscope.
You can tell that the waveform is not aliasing by use of the oscilliscope so you can actually see what the pattern is. You may have to play with the settings on the oscilliscope to remove the aliasing.


Scan tool observations
We used the Autoboss scan tool on the Range Rover.
The different functions on the scan tool to examine the CAN system were:
Control unit version
Fault codes
Acutal values(all select)
Actual values(manual select)

Systems controlled by the CAN:



Wiring diagram exercise
This wiring diagram shows most of the controls that you can operate as the passenger or driver such as the cruise control, air con and power windows.
The highspeed and low speed comes from the ECM on page 2.
The gateway is in the dahsboard control unit.
The system can be divided into each separate modules, this will help diagnosis by separating the problem from the CAN. Then by process of elimination you can figure out which module is bringing the CAN down.
The power window module would go to sleep as it is not always needed.
Cant measure the voltage or amperage on this circuit...

Controlled Area Network-Board

CAN Board.
Plug 1 is H-CAN. H-CAN is when the signal is positively switched.
Plug 2 is L-CAN. L-CAN is when the signal is earth switched.
Plug 3 is earth.


Normal

Right Indicator

Left indicator

Rear wiper

Stoplights

Fuel pump

Reverse lights


Identifying the input/output pins, Relay or transistor for the right hand indicator and rear wiper.
Right hand indicator:
Input 7
Output 5
Transistor

Rear wiper:
Input 9
Output 7
Relay

Identifying the voltage regulators and the inputs/outputs for them.
Regulator 1:U17805 on node A
Input supply 1 and 2
Output to Ve which is voltage supply for IC 18F258

Regulator 2:U17895 on node B
Input supply 1 and 2
Output to 14 VDD

Stop light circuit.
Node A input 5
RA2/AN2/Vref-
This sends out a specific signal to the CAN-H
The CAN-H goes through the connector to the Node B CAN module.
Which sends the signal to the IC.
The IC sends the appropriate signal to the correct circuit.
which is output circuit 3, this sends voltage to the photo diode, which passes the voltage onto the base of the transmitter which activates the stop lights.