Checking Wire From Transmission Control Module

NOTES:
- If a malfunction is recognized by the Engine Control Module (ECM) or the Transmission Control Module (TCM), it is indicated by the Malfunction Indicator Lamp (MIL) in the instrument cluster.
- If the TCM recognizes a malfunction, the MIL is switched on via the ECM.
- The MIL wiring is monitored by the ECM.

Checking requirement
- Control module coding OK, Computers and Control Systems

- Switch ignition ON.

- Using VAG 1551 scan tool, select "Read Measuring Value Block" function 08, display group 027, display field 1, Computers and Control Systems, refer to system diagnosis/display group diagnosis.

Indicated on display; note display field 1

Read measuring value block 27 -->
1 2 3 4

Specified value: 0

- Start engine and let idle. Specified value: 1
- Press H button
- Select "End Output" function 06
- Press -Q- button to confirm input.

If the specified value is not obtained, even though coding is OK:
- Connect VAG 1598/19 test box to ECM harness connector.
- Check wiring for open or short circuit between ECM and TCM, using wiring diagram.