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With Manufacturer's Scan Tool



Angle Sensors For Throttle Drive, Testing

Special tools and equipment






- VAG 1526 A
- VAG 1594 A
- VAG 1598/31
- VAS 5051 with VAS 5051/1

The angle sensors for throttle drive (-G187 and -G188) inform the engine control module of the position of the throttle valve. Both angle sensors are located in the throttle valve control module.

Test sequence
- Connect the vehicle diagnostic, testing and information system VAS 5051, and select the vehicle system "01 - Engine electronics" from the menu. When doing this the ignition should be switched on. Connecting VAS 5051/VAG1551 Scan Tool






Display on VAS 5051:
- Select the diagnosis function "08 - Read data block" from the menu -1-.






Display on VAS 5051:
1 - Enter display group
(figures up to 255)
- Using the keypad -2-, enter "062" to select Display group 062 and confirm entry with Q button.






Display on VAS 5051:
- Check display values for electronic throttle potentiometer voltages in display zones -1- and -2-.

Display Group 062:






NOTE: The engine control module converts the voltage readings from the angle senders into percentages of 5 V and displays them as percentages. (A supply voltage of 5 V is equivalent to 100%.)

- Observe display zones 1 and 2.
- Slowly depress accelerator to full throttle position.

The percentage value in display zone 1 should rise steadily between 3 and 93 % but without covering the full range of values.

The percentage value in display zone 2 should fall steadily between 97 and 3 % but without covering the full range of values.

NOTE:
- The reason why the value in display zone 1 rises and the value in display zone 2 falls is because the potentiometers (angle sensors) in the throttle valve control module work in opposite directions.
- The percentage value for the first potentiometer increases as the voltage rises toward 5 V because the voltage at this potentiometer increases as the throttle valve opens.
- The percentage value for the second potentiometer decreases as the voltage drops away from 5 V and toward 0 V because the voltage at this potentiometer decreases as the throttle valve opens.
- Press the <- arrow button to exit from the function "08 - Read data block".

If the display values do not appear as described:
- Test voltage supply and wiring to throttle valve control module. Pay particular attention to the connectors, which may have corroded or become detached.
- Test accelerator position sensors.

Testing voltage supply to throttle valve control module
- Unplug connector from throttle valve control module.
- Switch ignition on.






- Connect multimeter (voltage measurement range) as follows:

Connector Specification
Contact
2 + Ground approx. 5 V
2 + 6 approx. 5 V

If the specifications are not obtained:
- Test wiring between engine control module and throttle valve control module.

Testing wiring






- Unplug connector from throttle valve control module.
- Connect test box VAG 1598/31 to wiring harness for engine control module. Do not connect to the engine control module itself. Wiring and Component Testing Using VAG1598/31 Test Box
- Test for open circuit and short to Ground or positive in the following wiring connections:

Connector Test box VAG 1598/31
Contact Socket
1 92
2 83
3 117
4 84
5 118
6 91

- Correct any open/short circuit as necessary.

If no malfunction is detected:
- Install a new throttle valve control module.
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