Throttle Position Sensor: Testing and Inspection
Throttle Position (TP) Sensor, Checking
Special tools and equipment
- Multimeter (Fluke 83 or equivalent)
- VAG1594A connector test kit
- VAG1598/31 test box
- VAG1551 scan tool or VAG1552 mobile scan tool with VAG1551/3A cable
- Wiring diagram
Function
Both the Throttle Position (TP) sensor -G79- and the Sender -2- for accelerator pedal position -G185- are located at the accelerator pedal and communicate the driver's intentions to the ECM completely independently of each other. Both sensors are stored in one housing.
Test requirements
- Fuses must be OK.
- No DTCs in DTC memory
- Battery voltage must be at least 11.5 volts.
Test sequence
- Connect VAG1551 scan tool (VAG1552) and select the control module for engine electronics via address word 01. Ignition must be switched on for this:
Indicated on display:
Rapid data transfer HELP
Select function XX
- Press buttons -0- and -8- to select "Read measuring value block" function 08. Press -Q- button to confirm input.
Indicated on display:
Read measuring value block
Enter display group number XXX
- Press 0, 6 and 2 for the function "display group number 62", and then press Q to exit from input mode.
Indicated on display: (1 to 4 = display fields)
Read measuring value block 62 "
1 2 3 4
- Check specified value for Throttle Position (TP) sensor -G79- at idle stop in display field 3 Specification: 12 to 97%
- Check specified value for sender -2- for accelerator pedal position -G185- at idle stop in display field 4 Specification: 4 to 49 %
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%).
- Depress gas pedal slowly until Wide Open Throttle (WOT), and observe percent indication in display fields 3 and 4:
Percent indication in display field 3 must rise uniformly. The tolerance range 12 to 97 % is not used completely during this.
Percent indication in display field 4 must rise uniformly. In the process, the tolerance range of 4 to 49 % is not completely utilized.
NOTE: The indicated value in display field 3 must always be about twice as large as the value in display field 4.
If indications do not resemble description:
- Press -> button.
- Press buttons -0- and -6- to select "End Output" function 06. Press -Q- button to confirm input.
- Switch ignition off.
- Check voltage supply and wire connections of sensor for accelerator pedal position.
Checking voltage supply and wiring to control module
- Remove footwell cover (driver's side).
- Disconnect 6-pin harness connector for accelerator pedal position sensor.
- Switch ignition on.
- Connect multimeter to the following' connector terminals for voltage measurement.
Terminal 1 + Ground (GND)
Terminal 1 + 5
Terminal 2 + Ground (GND)
Terminal 2 + 3
Specification: at least 4.5 V
- Switch ignition off.
If specified values are not obtained:
- Connect VAG1598/31 test box to control module wiring harness. Engine Control Module (ECM) is not connected.
- Check for open circuits in wires between test box and connector according to wiring diagram.
Terminal 1 + socket 72
Terminal 2 + socket 73
Terminal 3 + socket 36
Terminal 4 + socket 35
Terminal 5 + socket 33
Terminal 6 + socket 34
Wire resistance: max: 1.5 Ohms
- Also check wires for short circuits to B+ or Ground (GND).
- Also check wires for short circuit to each other.
If no malfunctions are found in wires:
- Replace accelerator pedal position sensor.
- Perform work procedure "Procedure to follow after interruption of voltage supply":
- Read readiness code:
- If DTC memory was erased, readiness code must be re-generated: