INSTRUMENTS
E1
CIRCUIT OPERATION
1
CIRCUIT OPERATION
Engine Coolant Temperature Gauge
The engine coolant temperature gauge sensor has
the capability to sense from –40
_
C to +130
_
C. Petrol
and Diesel resistance valves are different.
Both Petrol and Diesel sensors are interfaced to the
Instrument Cluster (Z142) via the BeCM (Z238). The
resistance value then being represented by an A/D
data transfer generating the required angular
deflection on this gauge.
]
Fuel Gauge
When the fuel tank level is low (“E”), the resistance
value of the gauge sensor is 270
Ω
for petrol and
diesel engines. As the fuel level increases, the
resistance of the sensor decreases. When the fuel
tank is full, the resistance value of the sensor for
petrol engines is 19
Ω
and for diesel engines 25.8
Ω
.
When the fuel gauge sensors resistance value
increases to 175
Ω
(9 liters/2.25 US gallons, the low
fuel warning light will illuminate to warn of the fuel
status. Both Petrol and Diesel sensors are interfaced
to the Instrument Cluster (Z142) via the BeCM
(Z238). The resistance values then being
represented by an A/D data transfer generating the
required angular deflection on the gauge.
Speedometer
The signal to activate the gauge is originated at the
ABS wheel sensors, transmitted to the ABS ECU
(Z108) which then puts out a usable signal to the
Instrument Cluster (Z142) of 8000 pulses per mile or
4972 pulses per kilometer. The signal is also
transmitted to other ECU’s, such as the Engine
Control Module (ECM) (Z132) and the Cruise Control
ECU (Z121).
Tachometer
The tachometer will display the engine speed in
R.P.M. It will derive the engine speed from the
engine speed pulse train transmitted from the Engine
Control Module (ECM) (Z132).
The pulse rate for petrol engines will be 4 pulses per
engine revolution.
The pulse rate for diesel engines will be 3 pulses per
engine revolution.
Audible Warning
Receipt of an audible warning request signal from a
vehicle parameter/message condition shall cause the
BeCM (Z238) to generate the required number of
warning tones. The actuator sounder unit is located
at the rear of the Instrument Cluster (Z142).
See message listing for categories/priority and levels
of audible warnings.