Transmission Diagnostic Trouble Codes; Tccs Torque Convertor Clutch Solenoid; Tcs Torque Convertor Slip; Tissa Turbine Input Shaft Speed - Aston Martin DB7 Workshop Manual

The Aston Martin Lagonda Diagnostic System
Users Guide
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TCCS Torque Convertor Clutch Solenoid
The torque converter clutch solenoid is mounted on the
valve body. The signal is Pulse Width Modulated at 32Hz
to provide closed loop control of the pressure across the
converter clutch plates. 1 bit = 0.39% Range 0 to 100%
TP Throttle Position
This is provided by the EECV Engine Management System
as a Pulse Width Modulated signal derived from the
throttle position signal read by that module from the
throttle position sensor.
TCS Torque Convertor Slip
Torque converter slip is defined as the difference between
the Input/turbine (ni) speed and the Engine speed (Ne):
Slip = Ne-Ni. The PWM duty cycle may increase from 0
to 100% when TCC is fully applied. In practice a 100%
duty cycle will be achieved only if a large slip is detected.
Normal ly only a 50 to 9 5 % duty cycle will be required for
full application of the TCC. Slip is expressed in rpm. 1 Bit
- 1/8 rpm. Range -4096 to +4096 rpm.
TCSW Transmission Control Switch
A three position switch allows the driver to select Sport,
Normal or 1st Gear Inhibit mode. When 'Sport' is selected
gearshifts take place at higher engine revs. When '1st
Gear Inhibit' is selected, the transmission only operates in
the higher forward ratios to prevent wheel slip in icy
conditions.
TISSA Turbine Input Shaft Speed
Turbine speed is the speed of the input shaft of the
transmission measured by the input speed sensor mounted
on the transmission. An alternating waveform is induced
in the sensor by 31 serrations on the forward clutch
housing as it rotates. The waveform frequency and
amplitude is low at low speeds and high at high speeds.
The TCM changes this signal into a digital signal. 1 bit =
1/8 RPM. Range: 0 - 8192 RPM.
TOS+ Transmission Output Speed
The output speed sensor is mounted on the transmission
case and measures the speed of the output shaft. As the
shaft rotates an alternating waveform is induced in the
sensor which varies in frequency and voltage. The wave
form is converted into a digital signal by the TCM and used
to control TCC, line pressure, shift timing and torque
management. 1 bit = 1/8 RPM. Range 0 - 8 1 9 2 RPM
TRX Transmission Control Switch X
TRY Transmission Control Switch Y
TRZ Transmission Control Switch Z
The transmission range is detected by the pressure switch
manifold (PSM) and input to the TCM. The signal consists
of three discrete lines X, Y, Z which transmit a 3 bit binary
code as shown in the table below.
0 = open circuit
1 = short circuit to ground
X Y Z
p
R
N
D
3
2
Error
0
1
0
1
0
0
1
0
0
0
0
1
1
1
0
1
0
0
1
0
1
VS Vehicle Speed
Veh icie speed is derived from a pu Ised wave form generated
by the speed sensor in the hypoid unit. There are 40 pulses
per shaft rotation and the TCM converts this to vehicle
speed and applies correction for axle ratio and road wheel
diameter. 1 bit - 1 kph. Range 0 - 255kph
Transmission Diagnostic Trouble Codes
The diagnostic trouble codes supported by the C M 4L80-
E Transmission Control Module are covered indetail inthe
DB7 OBD II Diagnostics Manual.
TOT Transmission Oil Temperature
The transmission temperature sensor signal is used to
control TCC and line pressure. It has a negative temperature
coefficient so when the temperature is cold its resistance
is high and the TCM sees a high voltage. Asthe temperature
warms the volts drop across the sensor decreases and the
signal voltage becomes lower. The TCM converts this
analogue input into a digital signal.
1 bit = 1 °C Range -55°C to +200°C.
9-42
September 1996