Throttle Position Sensor: Testing and Inspection
Throttle Position (TP) Sensor -G79 and Sender -2- for accelerator pedal position -G185, checking
The Throttle Position (TP) Sensor -G79 and Sender -2- for accelerator pedal position -G185 are located at the accelerator pedal. Both sensors inform (completely independently of the other) the engine control module of the driver's throttle requirement (pedal position). Both sensors are located in a single housing.
- Connect Vehicle Diagnostic, Testing and Information System VA55051 or VAG 1551 Scan Tool and select engine electronics control module by entering address word "01". When doing this the ignition must be switched on.
Indicated on display
Rapid data transfer HELP
Select function XX
- Press buttons -0- and -8- to select function "Read Measuring Value Block" and confirm entry with -Q- button.
Indicated on display
Read Measuring Value Block Q
Input display group number XXX
- Press buttons -0-, -6- and -2- to select "Display Group 062" and confirm entry with -Q- button.
Indicated on display
Read Measuring Value Block 62 ->
1 2 3 4
- Check specified display values for electronic throttle potentiometer voltages.
- Observe display fields 3 and 4.
- Slowly depress accelerator to wide open throttle position.
The percentage value in display field 3 should rise steadily, but without covering the full tolerance range between 12 and 92 %.
The percentage value in display field 4 should also rise steadily but without covering the full range of values (in this case 4 to 49 %).
NOTE: The value shown in display field 3 should always be about twice as high as the value shown in display field 4.
If the display values do not appear as described:
- Check voltage supply and wiring to accelerator position senders.
- Adjust accelerator position sensors.
Checking voltage supply of accelerator position sensors
- Remove storage compartment on driver's side.
- Disconnect harness connector for accelerator position sensor.
NOTE: The connector is clipped onto the pedal bracket near the brake light switch.
- Switch ignition on.
- Connect multimeter (voltage range) between the following sockets on the connector:
6-pin connector on Specification
wiring harness, socket
2 + Ground (GND) approx. 5 V
1 + 3 approx. 5 V
5 + Ground (GND) approx. 5 V
5 + 4 approx. 5 V
If the specifications are obtained:
- Check signal wiring.
If the specifications are not obtained:
- Check wiring between engine control module and accelerator position sensors.
Checking signal wiring and wiring connections between accelerator position sensors and engine control module
- Connect VAG 1598/31 test box to wiring harness for engine control module. DO NOT connect to engine control module itself, Refer to "Scan Tool Testing/Scan Tool Connecting and Initial Checks/Connecting VAG 1598/31 Test Box" Testing and Inspection
- Check for open circuit and short to B+ or Ground (GND) in the following wiring connections:
Connector VAG 1598/31
Socket test box socket
1 (signal wire) 35
2 73
3 36
4 33
5 72
6 (signal wire) 34
- Correct any open/short circuit as necessary.
If no wiring malfunction is detected:
- Replace accelerator position sensors.
- Display readiness code, Refer to "Monitors, Trips and/or Drive Cycle (Readiness Codes)/Displaying Readiness Code" Testing and Inspection . Readiness code must be generated if DTC memory was erased, Refer to "Monitors, Trips and/or Drive Cycle (Readiness Codes)/Generating Readiness Code" Testing and Inspection