Transmission Position Sensor/Switch: Testing and Inspection

NOTE: The Engine Control Module (ECM) uses this signal to recognize the transmission range selector lever position. When a driving mode is selected, idle speed should drop by approx. 50 RPM to reduce creep.

CHECKING REQUIREMENTS:
- Control module coding OK.

CHECKING:
- Switch ignition ON.
- Using VAG 1551 scan tool, select "Read Measuring Value Block" function 08, display group 004, display field 4, [1][2]Read Measuring Value Block (Function 08).

Indicated on display:

Read measuring value block 4 -->
1 2 3 4

Specified Value: XXX_1X (TR selector lever in P or N).

- Apply brake and select drive mode (1, 2, 3, R or D).

Specified Value: XXX OX.

NOTE: The shift inputs (identified by an X) do not need to be referred to for checking selector lever position.

- Press arrow button.
- Select "End Output" function 06 and press -0- button to confirm input.

If a display did NOT change, even though coding is OK:
- Connect VAG 1598/19 test box to ECM harness connector.
- Connect VAG 1527B voltage tester between test box sockets 11B (signal) and 10B (constant B+/terminal 30).

Voltage tester must light up (with TR selector lever in P or N), then go out with drive mode (1, 2, 3, R or D) selected.

If voltage tester lights up and goes out when drive mode is selected, even though the range indicator in the "Read measuring value block" is OK:
- Replace ECM.

If voltage tester lights up constantly or not at all:





- Check wiring for short to ground, short to B+ or open circuit between ECM terminal 11B and multi-function switch, using wiring diagram.

If wiring is OK:
- Check multi-function switch, Automatic Transmission.