Electronic Throttle Actuator: Testing and Inspection
Angle sensor 1 for throttle drive (power accelerator actuation) - G187 - and angle sensor 1 for throttle drive (power accelerator actuation) - G188 - inform the Engine Control Module (ECM) about the position of the throttle valve. Both angle sensors are located in the throttle valve control module.
Test sequence
- Connect VAS5051 tester or VAG 1551 scan tool and select control module for engine electronics using "address word" 01. Ignition must remain switched on for this.
When indicated on display:
Rapid data transfer HELP
Select function XX
- Press buttons -0- and -8- to select "Read Measuring Value Block" and press -Q- button to confirm input.
When indicated on display:
Read Measuring Value Block Q
Input display group number XXX
- Press buttons -0- -6- and -2- to select "display group number 062" and press -Q- button to confirm input.
Indicated on display:
Read Measuring Value Block 62 ->
1 2 3 4
- Check specified value for E - Gas potentiometer voltages.
Display Group 62:
NOTE: Engine Control Module (ECM) calculates the voltage values of the angle sensors in percent relative to 5 volts and displays these percentage values. (5 volts supply voltage represents 100 %).
- Observe display field 1 and 2.
- Slowly depress accelerator pedal completely.
Percent indication in display field 1 must climb uniformly. The tolerance range 3 - 93 % is not used completely during this.
Percent indication in display field 2 must decrease uniformly. The tolerance range 97 - 3 % is not used completely during this.
NOTE:
- The reason that the indication in display field 1 climbs but the indication in display field 2 decreases, is due to the inverse relationship of the potentiometers (angle sensors) in the throttle valve control module.
- This means that the voltage of the one angle sensor runs toward 5 volts. (The more the throttle valve is opened, the larger the voltage; percent indication climbs).
- The voltage of angle sensor 2 runs from 5 volts toward 0 volts. (The more the throttle valve is opened, the smaller the voltage; percent indication decreases).
If indications do not resemble description:
- Check voltage supply and wire connections of throttle valve control module. Pay particular attention to harness connectors that could be loose or corroded.
- Check accelerator pedal position sensor.
Check voltage supply throttle valve control module
- Disconnect connector from throttle valve control module.
- Switch ignition on.
- Connect multimeter for voltage measurement as follows:
Harness connector terminal Specified value
2 + Ground approx. 5 V
2 + 6 approx. 5V
If specified values are obtained:
- Also check signal wires and activation wires of throttle valve actuator.
If specified values are not obtained:
- Check wire connections from Engine Control Module (ECM) to throttle valve control module.
Checking wire connections
- Disconnect connector from throttle valve control module.
- Connect VAG 1598/31 test box at wiring harness to ECM, do not connect ECM.
- Check the following wire connections for open circuit and short circuit to Ground and B+:
Harness connector terminal VAG 1598/31 test box socket
1 92
2 83
3 117
4 84
5 118
6 91
- Repair open circuit or short circuit if necessary.
If no malfunctions are found in wires:
- Replace throttle valve control module.