On-Board Diagnostics II

Functions:
Automatic transmission 01N operates by electro-hydraulic control. The Transmission Control Module (TCM) -J217- receives input signals from those components that affect gear selection, and delivers output signals to solenoid valves that control gear selection in the valve body.

The "On Board Diagnostic" capability refers specifically to the electrical and electronic controls. In the event of an electrical or electronic malfunction or an open circuit, the cause of the malfunction can be determined quickly.

Transmission Control Module (TCM) Operation:
The TCM -J217- is equipped with Diagnostic Trouble Code (DTC) memory. If malfunctions occur in the monitored sensors or components, they are recognized by the TCM and stored as Diagnostic Trouble Codes (DTCs) in DTC memory, along with an indication of the type of malfunction.

The TCM evaluates the information, distinguishes different types of malfunctions, and stores these as diagnostic trouble codes until DTC memory is checked and erased using the VAG 1551 scan tool.

Malfunction Recognition:
If a malfunction exists for a certain time, it is recognized and stored as a static malfunction.

A malfunction that is recognized once, and does not occur again within a specified period, is identified as a "sporadic" malfunction, and coded as such.

Sporadic malfunctions are identified by an "/SP" designation on the VAG1551 or VAG1552 scan tool display when checking DTC memory. If the printer is switched on, a "sporadic DTC designation is also printed.

"Sporadic" malfunctions that occur but are not recognized again are automatically erased:
- OBD II: after 40 cold starts (with warm-up)

The On Board Diagnostic (OBD) program can also be carried out using the VAG1552 scan tool, or a Generic Scan Tool (GST) and address code 33. With Generic Scan Tool

Transmission Control Module (TCM) Back-up Mode:
If certain critical malfunctions occur while driving, the transmission continues to operate, but switches to a "back-up" mode.

If the malfunction occurs in a forward gear, the back-up mode selects 3rd gear. The vehicle can also be driven in transmission ranges "1," "2," "3" and "R" while in the back-up mode.

If the malfunction occurs while the selector lever is in position "1," "P," "N" or "R," the back-up mode for that gear selection is activated.

When a malfunction triggers the switch to back-up mode, the transmission operates in that mode for as long as the ignition remains switched on.

During subsequent operation of the vehicle, if the selector lever is in the "D," "3" or "2" position and the malfunction occurs again, 3rd gear will remain hydraulically activated until the malfunction is repaired.





Malfunctions That Activate Back-up Mode (OBD II)





On Board Diagnostic (OBD) Capability:
Causes of electrical malfunctions that affect vehicle operation can be determined using the VAG1551 or VAG1552 scan tool.

OBD capabilities are only accessible using the VAG1551 or VAG1552 scan tool in "Rapid data transfer" operating mode 1, connected to the TCM via the Data Link Connector (DLC).

Electrical and electronic component locations, refer to "Component Locations". Locations

WARNING: When driving or riding in an airbag-equipped vehicle, never hold test equipment in your hands or lap while the vehicle is in motion. Objects between you and the airbag can increase the risk of injury in an accident.