EDU2 Trip Computer and Clock
EDU2 Trip Computer And Clock Diagrams:
EDU2 Trip Computer And Clock Components:
Locations of components
3 Earthing point, facia
At the left-hand front speaker socket
7 Earthing point
On the left-hand wheel housing
16 Instrument lighting rheostat
On the left-hand side of the facia
20 Ignition switch
On the right-hand side of the steering column
22A Fuse board
Behind the access panel in the glove compartment
46 Fuel level transmitter
In the fuel tank (terminals accessible from the luggage compartment)
47A Fuel gauge
In the combined instrument 49/241 Clock/DCC trip computer on the right-hand side of the instrument panel
57 Three-pole connector
On the clock
59 Two-pole connector
One behind the EDU2 trip computer
One at the coolant expansion tank
One in the engine compartment at the windscreen wiper motor
One on the engine, under the intake manifold
65 Earthing point
Under the back seat
67 Six-pole connector
In the engine compartment, at the windscreen wiper motor
110 Tachometer
In the combined instrument
122 Eight-pole connector
Two behind the EDU2 trip computer two on the DCC trip computer/clock
132 Sensor for the speed transmitter
In the speedometer, in the combined instrument
159 Distribution terminal +15
In the electrical distribution box behind the glove compartment
200 Control unit for the fuel injection system
On the left-hand side of the engine compartment, at the bulkhead
210 EDU2 trip computer
In the combined instrument
230 Distribution terminal +30
In the electrical distribution box behind the glove compartment
242 Coolant level switch
In the coolant expansion tank
243 Engine oil level switch
On the oil sump (bulkhead side)
244 Connection for heater
In the centre console, behind the facia
245 Selector lever switch (automatic transmission)
At the selector lever
286 Outdoor temperature sensor (trip computer)
On the left-hand side, behind the front spoiler
Operation
The EDU2 (Electronic Display Unit) trip computer is located in the combined instrument and provides the following information:
Left-hand part of the display
Instantaneous and average fuel consumption
Range with remaining fuel
Battery voltage and condition
Ambient temperature
Right-hand part, upper half
Gear selected (for cars with automatic transmission)
Right-hand part, lower half
"CHECK ENGINE" (Fault in fuel injection system or 116 lambda ignition system for US and CA)
"CHECK OIL LEVEL" (Low oil level)
"CHECK RADIATOR LEVEL" (Low coolant level)
A fault code may also be displayed in the event of a fault. (See under "Fault-tracing hints".)
On 116 Lambda cars for US and CA, CHECK ENGINE warning lamp 47P will also flash in case of a fault in the fuel-injection or ignition system.
The various computer functions and the units (e.g. km or miles) used in displaying information are selected by means of the two buttons, R and INFO. The buttons are mounted on clock 49, or on DCC trip computer 241 if the latter is fitted. Operating instructions and other information on the EDU2 trip computer are provided in the Service Manual, Group 3:1, Electrical system, Instruments.
Trip computer 210 receives a constant supply from fuse 17, and is also supplied from fuse 13 when the ignition switch is in the drive position.
The brightness of the display under daylight conditions is controlled by a sensor mounted on the DCC unit or clock. In darkness, the brightness can be controlled by means of instrument lighting rheostat 16.
To display the instantaneous or average fuel consumption, the trip computer requires information on:
the road speed, from speed transmitter sensor 132
the current fuel consumption from control unit 200 for the fuel injection system. The frequency of the control pulses supplied from the control unit to the fuel injection valves (terminal 13) corresponds to the instantaneous consumption.
Fuel level transmitter 46 is connected to the trip computer in order to indicate the range or distance which can be covered with the fuel remaining in the tank. Note that fuel gauge 47A receives its input signal from the trip computer (cable 663 GN) and not directly from the transmitter.
Information on the ambient temperature is provided by sensor 286, located behind the front spoiler. This temperature is not displayed by the EDU2 if the DCC trip computer is fitted.
Warning signals for oil level and coolant level are obtained from level switches 243 and 242 respectively, which close if the level should drop below a predetermined level. If a fault should occur in the fuel system, a warning signal (positive voltage) will be supplied from terminal 19 of control unit 200.
On cars with automatic transmission, the trip computer is connected to selector lever switch 245.
Fault-tracing hints
The trip computer will become operative when the ignition switch is turned to the drive position.
If no information at all is shown on the trip computer display, first check points 1-5 below. If a fault code appears on the display, check the list of codes at the end of this section for clarification.
1. Check fuses 13 and 17 and check that the supply to them is live.
2. Check that the supply to pins 6 and 4 of the trip computer is live.
3. Check that the contact surfaces of the connectors are undamaged and clean. This is important since the currents involved are low.
4. Check the wiring and the earth connections.
5. Check the voltage at terminal 1 of sensor 132.
The self-diagnostics of the EDU2 may be used as an aid to fault tracing. If any of the following fault codes is displayed, locate and rectify the fault as recommended in each case. (The code will disappear from the display when the fault has been rectified.)
F1 Fault in gear selection transmitter or associated wiring: All orange segments under PRND321 will light up simultaneously (on cars with automatic transmission).
F2 Short-circuit in outside temperature sensor. F3 Short-circuit in fuel level transmitter.
F4 Unreliable performance of the trip computer itself.
If the ambient temperature is not displayed even though F2 does not appear, the sensor may have fallen off. (Note: The ambient temperature will not be displayed if the DCC trip computer is fitted.)
NOTE:
If the EDU fails to operate properly, check the eight-pole connectors behind the combined instrument before replacing the EDU.
If one-half of the EDU fails to light up, check the bulb first.