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Home >> Volvo >> 2004 >> S60 L5-2.3L Turbo VIN 53 B5234T3 >> Repair and Diagnosis >> Powertrain Management >> Computers and Control Systems >> Electronic Throttle Actuator >> Description and Operation

Electronic Throttle Actuator: Description and Operation



ETA (Electronic Throttle Actuator)







1. Hall sensor
2. Spring
3. Spring
4. Throttle
5. DC motor
6. Terminal pins
7. Gear wheel
8. Gear sector
9. Permanent magnets.

Function
The engine control module (ECM) uses a PWM signal to control the position of the DC motor and with it the position of the throttle.

By changing the polarity of the power supply, the DC motor can be run in both directions.

Two permanent magnets in the gear sector on the throttle spindle are used to check the position of the throttle.
- The permanent magnets affect the two Hall sensors in the cover
- When the throttle spindle is turned, the position and strength of the magnetic field changes, which affects the Hall sensors
- Internal circuits convert the hall signals to two voltage signals which are transmitted to the engine control module (ECM).

The two signals are offset internally.
- The voltage of the main signal is 0.6 V when the throttle is shut. The voltage increases by 40 mV per degree that the throttle is opened. The voltage is approximately 4 V at wide open throttle (WOT)
- The voltage of the redundant signal is 1.48 V when the throttle is shut. The voltage increases by 32 mV per degree that the throttle is opened. The voltage is approximately 4.2 V at wide open throttle (WOT).

In order for the engine control module (ECM) to determine whether the voltage signals are plausible, the actual values are compared with stored desired values. A diagnostic trouble code (DTC) is stored if the values are outside certain tolerances. In certain situations, depending on the nature of the fault, this may mean that the power supply to the DC motor is broken. If this happens, the throttle, through the use of springs, is moved to a position which makes the car drivable (with limited driveablity).

- The conditions for running the adaptation are that the ignition key is turned from position I to position II and when the engine is turned off. The adaptation is stopped when the car is cranked (i.e. the ignition key is turned to position III)
- During adaptation, the throttle switches from the Limp Home mode to the mechanically closed position. The engine control module (ECM) updates the values if these deviate from the stored values
- The ETA (Electronic Throttle Actuator) has a return spring and a Limp Home spring. The springs are always checked after the engine is switched off
- The DC motor first closes the throttle. The Limp Home spring then resets the throttle to the Limp Home position. The throttle is then opened a few degrees, whereupon the return spring closes the throttle to the Limp Home position. A diagnostic trouble code (DTC) is stored if the throttle does not reach the Limp Home position within a certain time
- Diagnostic trouble codes (DTCs) related to the ETA (Electronic Throttle Actuator) are stored in the engine control module (ECM)
- During adaptation and spring control there is noise as the throttle moves to different positions
- The connector terminal pins are gold plated. A damaged terminal pin surface can interfere with the function
- The terminating resistor for the CAN network has been moved to the engine control module (ECM).

Diagnostics
- The diagnostics for the ETA (Electronic Throttle Actuator) have changed in comparison with the previous ETM (Electronic Throttle Module), Magneti-Marelli. The engine control module (ECM) continuously reads off the engine torque. If the torque exceeds the expected value, for example if the throttle opening angle is too great, an error flag is stored and the system is reconfigured. This means that the torque is limited using other control mechanisms than the normal, for example fuel shut-off. The cruise control will be disengaged if it is in use
- The following happens, depending on the character of the fault. If the fault persists for a longer period a diagnostic trouble code (DTC) is stored. If the function returns to normal, the error flag goes out and the reconfiguration stops. No diagnostic trouble code (DTC) is stored if the error flag has only been stored for a short time
- In comparison to previous diagnostics, the tolerances before the diagnostic trouble code (DTC) is stored have increased, while the tolerance for the error flag have been reduced. The actual diagnostic trouble code (DTC) is first stored after the error flag has been in the fault area for a certain amount of time
- A new function has been introduced in VADIS/VIDA for fault-tracing
- The new fault-tracing functions are based on there being a tool which reads out ranking values for relevant diagnostic trouble codes (DTCs)
- A ranking code for a diagnostic trouble code (DTC) indicates how closes the system is to storing a diagnostic trouble code (DTC)
- A high ranking value can result in reconfiguration, even though no diagnostic trouble code (DTC) is stored. The customer may have noticed a specific abnormality without a diagnostic trouble code (DTC) being stored. The cause of this can be identified by reading off the ranking values
- The tool can be used to read off two ranking value positions: "worst" and "latest". "worst" is the highest ranking value since the diagnostic trouble code (DTC) was erased. "latest" is the ranking value of the diagnostic trouble code (DTC) at the time it is read.
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