S80 T6 L6-2.9L Turbo VIN 91 B6294T (2002)
The throttle unit is mounted on the engine intake manifold, the location can vary depending on engine type. 5 cylinder turbocharged engines and 6
cylinder engines have the throttle unit mounted under the intake manifold. Others have it mounted on the side of the intake manifold. The throttle unit's
primary task is to control the amount of air to the engine from the request from the Engine control module (ECM).
The Electronic throttle module (ETM) is in the throttle unit, which means that it works as its own control module on the high speed side of the CAN.
The connection to the CAN takes up two of the six pins in the throttle unit's connector, the remaining four are taken up by:
-
Voltage supply, 12 V via the engine control system's system relay.
-
Ground terminals, separated from the engine control system's other ground terminals.
-
Information about the brake pedal's position from the brake lamp switch.
-
Information about the position of the accelerator pedal from the accelerator pedal unit's PWM sensor.
In order for the Electronic throttle module (ETM) to carry out the main task of controlling the air flow to the engine, the voltage supply, ground and
contact with the CAN is sufficient. The other two signals about the position of the brake pedal and the accelerator pedal are used as a safety function in
case a problem should occur with CAN communication. This makes it possible to continue driving, but with reduced driveablity. The signals are used,
among other things, to carry out a plausibility check of the desired throttle angle that comes from the Engine control module (ECM) via CAN.
In addition, the throttle unit consists of a further number of components such as throttle housing, throttle disc, throttle spindle, torque motor, throttle
position sensor (potentiometers), spring unit etc.
In one end the throttle unit contains a stepless torque motor that is directly operated on the throttle spindle. The torque motor is supplied with 12 V and
controlled by the Electronic throttle module (ETM). In the other end there is the throttle's spring unit and the mechanical stop for the smallest and largest
throttle openings.
Outside the torque motor and the spring unit, out on the relevant end there is a throttle position sensor (potentiometer). The two position sensors are
mechanically connected to each other via the throttle spindle.
