4A•6 Fuel and exhaust systems
to the speed of the vehicle. This has the
effect of transferring torque to the wheel
with most traction.
d) System switches: a pressure switch in
the TCS actuator is activated at a pressure
of 6.0 bars, and this illuminates a TCS
function light on the instrument panel,
informing the driver that the TCS system is
operating and attempting to counteract
wheelspin. If the system develops a fault,
the "TCS CTRL" warning light will be
illuminated permanently. However, if the
TCS system has been in operation for a
long time, the "TCS CTRL" warning light
will flash, to inform the driver that the TCS
system is temporarily inoperative, in order
to prevent overheating of the brakes.
e) Main control switch: the main control
switch is located on the facia panel.
2 In the event of a fault in the traction control
system, first check all relevant wiring for
security. If a fault arises on the road, a back-
up mode can be engaged by fully releasing the
accelerator pedal, then depressing it again. In
this mode, the throttle is operated by a cable.
In back-up mode, engine performance will be
limited, the accelerator pedal will be stiffer,
and the cruise control and air conditioning
systems will be inoperative. Further testing of
the system is best left to a Saab dealer, who
will have the necessary diagnostic equipment
to find the fault quickly. It is not possible to
make any adjustment to the system.
Accelerator pedal potentiometer
3 Working inside the car, disconnect the
wiring plug from the potentiometer (see
4 Disconnect the potentiometer arm from the
5 Unbolt and remove the unit.
6 Refitting is a reversal of removal.
7 Disconnect the wiring plug from the throttle
potentiometer/motor (see illustration).
8 Disconnect the throttle lever.
9 Unbolt and remove the unit.
10 Refitting is a reversal of removal.
6.7 ETS Throttle potentiometer/motor
ETS control module
Warning: If a new control module
is to be fitted, note that it must be
programmed (manual or
automatic transmission) by a
Saab dealer before connecting the wiring
plug (new modules are supplied
unprogrammed). Also note that the module
is extremely sensitive to static electricity,
and it is important to "earth" yourself
before (and while) working on it.
11 Move the left-hand front seat as far
forwards as possible.
12 Lift the carpet, then unbolt and remove the
13 Disconnect the wiring plug, and remove
the control module from inside the car. On
automatic transmission models, remove the
ASR module from the top of the ETS control
14 Refitting is a reversal of removal.
15 Remove the automatic climate control
panel, with reference to Chapter 3.
16 Press out the warning light, and
disconnect the wiring plug.
17 Refitting is a reversal of removal.
Note: The information given in this Chapter is
correct at the time of writing, and applies only
to petrols currently available in the UK. If
updated information is thought to be required,
check with a Saab dealer. If travelling abroad,
consult one of the motoring organisations (or a
similar authority) for advice on the petrols
available, and their suitability for your vehicle.
1 The fuel recommended by Saab is given in
the Specifications at the start of this Chapter,
followed by the equivalent petrol currently on
sale in the UK.
2 RON and MON are different testing
standards; RON stands for Research Octane
Number (also written as RM), while MON
stands for Motor Octane Number (also written
3 All Saab 9000 models are designed to run on
fuel with a minimum octane rating of 91 (RON),
but are more efficient with the higher octane
fuels listed in the specifications.
LH-Jetronic fuel injection
The LH-Jetronic fuel injection system is a
microprocessor-controlled fuel management
system, which continuously monitors the
engine using various sensors, and provides
the correct amount of fuel necessary for
complete combustion under all engine
conditions (see illustration). Data from the
sensors is processed in the fuel system
electronic control unit (ECU) in order to
determine the opening period of the
injectors for the exact amount of fuel to be
injected into the inlet manifold. The
system is of the simultaneous type, which
means that all injectors open and close at the
same time. They open once for each
revolution of the crankshaft, except during
cold starting, when they open twice for each
revolution. On Turbo models manufactured up
to 1989, a separate ECU is used to control the
turbocharging function; from this date
onwards, however, the function is
incorporated in the Direct Ignition ECU. Where
a catalytic converter is fitted (later models), a
lambda sensor is incorporated in the LH-
The main components of the system are as
a) ECU: the electronic control unit controls
the entire operation of the fuel injection
b) Injectors: each fuel injector consists of a
solenoid-operated needle valve, which
opens under the commands from the
ECU. Fuel from the fuel rail is then
delivered through the injector nozzle into
the inlet manifold.
c) Airflow meter: the airflow meter
measures the amount of air entering the
engine by means of a hot wire.
d) Temperature sensor: the coolant
temperature sensor monitors the engine
e) Auxiliary air valve: the auxiliary air valve
provides additional air when the
engine is cold. It is only fitted to 1985
f) Idle air control valve: the idle air control
valve controls the volume of air bypassing
the throttle butterfly. It is fitted to 1986-on
g) Throttle position switch: the throttle
position switch informs the ECU of the
throttle butterfly position.
h) Fuel pump: the fuel pump is housed in
the fuel tank. The pump housing
6.3 ETS accelerator pedal potentiometer