Electronic Throttle Actuator Position Sensor: Testing and Inspection

Angle Sensors For Throttle Drive, Checking







Special tools and equipment
- VAG1526A or Fluke 83 Multimeter
- VAG1594A Connector test kit
- VAG1598/31 Test box
- VAS5051 Vehicle diagnosis, testing and information system with VAS5051/1 Adapter

Angle sensor -1- for throttle drive (power accelerator actuation) -G187- and Angle sensor -2- 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.

Work sequence
- Connect VAS5051 tester, Vehicle Diagnostic, Testing and Information System VAS 5051, Connecting and Selecting Functions and select vehicle system "01 - Engine electronics". Ignition must be switched on.







Display on VAS5051:
- Select diagnostic function "08 - read measured value block" in selection -1-.







Display on VAS5051:
1 - Enter display group. Max. input value = 255
- Select function "062" in button field -2- for "display group number 062" and press Q button to confirm input.







Display on VAS5051:
- Check specified values for EPC potentiometer (throttle valve angle sensor) voltages in display fields 1 and 2.







- Observe display field 1 and 2.
- Slowly depress accelerator pedal completely.

Percent indication in display field 1 must rise uniformly. Tolerance range of 3 to 93% is not completely utilized.

Percent indication in display field 2 must decrease uniformly. Tolerance range 97 to 3 % is not completely utilized.

NOTE:
- The reason why the value indicated in display field 1 climbs, while the value indicated in display field 2 decreases, has to do with the fact that the potentiometers (angle sensors) in the throttle valve control module run in opposite directions.
- This means that the voltage tap of angle sensor 1 runs from 0 to 5 volts. (The more the throttle valve is opened, the larger the voltage; percent indication climbs).
- The voltage tap of angle sensor 2 runs from 5 to 0 volts. (The more the throttle valve is opened, the lower the voltage; percentage decreases).

- Press <- button to end function "08 - Read measuring value block".

If indications do not resemble description:
- Check voltage supply and wiring connections of throttle valve control module. Pay particular attention to harness connectors that could be loose or corroded.
- Check accelerator pedal position sensor.

Checking voltage supply of 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 (GND) about 5 V
2 + 6 about 5 V

If specified values are not obtained:
- Check wiring connections from Engine Control Module (ECM) to throttle valve control module.

Checking wiring connections







- Pull connector off throttle valve control module.
- Connect VAG1598/31 test box at wiring harness to Engine Control Module (ECM) but do not connect ECM.
- Check following wiring connections for open circuit and short circuit to Ground (GND) and B+:

Harness connector Terminal VAG1598/31 test box Socket
1 92
2 83
3 117
4 84
5 118
6 91

- Repair open circuit in wiring or short circuit if necessary.

If no malfunctions are found in wires:
- Replace throttle valve control module.