Throttle Position Switch: Testing and Inspection

Closed Throttle Position (CTP) Switch, Checking

The CTP switch is located at the rear of the throttle body, at the Throttle Position (TP) sensor.
- Connect VAG1551 or VAG1552 Scan Tool (ST), and press buttons -0- and -1- to insert "Engine Electronics" address word 01 (engine running at idle).

Indicated on display
Rapid data transfer HELP
Select function XX

- Press buttons -0- and -8- to select "Read Measuring Value Block" function 08, and press -Q- button to confirm input.

Indicated on display
Read Measuring Value Block
Input display group number XXX

- Press buttons -0-, -0- and -4- to input display group number 4 (004), and press -Q- button to confirm input.

Indicated on display
Read Measuring Value Block 4 ->
1 2 3 4

- Check specified values for basic functions at engine idle speed (display field 4):






Specified value in display field 4: "Idle"

If display does not change as described:
- Adjust accelerator pedal cable or linkage for cruise control.
- Check Throttle Position (TP) sensor for contamination.

If "Part throt" is displayed only after longer accelerator pedal travel:
- Adjust CTP switch.
- Briefly touch accelerator pedal (only a few millimeters).
Specified value: "Part throt"

If accelerator pedal cable adjustment is OK:
- Check CTP switch and wiring.

Checking Wiring
- Connect VAG1598/19 test box to ECM harness connector.






- Disconnect harness connector from Throttle Position (TP) sensor.

- Check wiring for continuity or short circuit:

TP sensor connector VAG1598/19 test box socket (ECM terminal)
terminal
4(Ground) D11 (Ground)
6 B4






- Repair wiring to correct open or short circuit as necessary.

NOTE: When repairing terminals in TP sensor connector, be sure to use only gold-plated terminals.

If wiring is OK:
- Check CTP switch.
- Reconnect TP sensor harness connector.
- Connect multimeter US 1119 (Fluke 83 or equivalent) and check for continuity between terminals D11 and B4.

Specified value: continuity when throttle valve is closed
- Open throttle valve
Specified value: no continuity

If results are not as specified:
- Replace Throttle Position (TP) sensor.
- Check readiness code. If DTC memory has been erased, generate new readiness code.