Control Module Behavior With Transmission Malfunction

Control Module Behavior with Transmission Malfunction

The control module works with sophisticated software. This software has the ability to execute electrical functions, monitor and control within milliseconds. Everything modern transmission electronics have going for them is located in this control module. This should be considered during troubleshooting.

However, no electronics can do what they were not designed to do. Likewise, it is not possible to detect electronically, for example, where the transmission housing is leaking and oil is escaping. However, it is possible to detect the effects of "low oil". A failure in "gear monitoring" would be recognized causing the control module to respond that both clutches are open (no traction).

You should know this during troubleshooting and also when working with the Volkswagen tester. It is possible that the cause for the malfunction might not be found during Guided Fault Finding.

Aside from the software that makes it possible for the transmission to operate, much was also done to protect the transmission in case of a malfunction (safety functions). When necessary, malfunctions are saved and a replacement program is started.

Control module behavior during a malfunction

If a component in the transmission malfunctions, the control module reacts with a replacement function. In order to protect the transmission as much as possible, 4 malfunction reactions are differentiated:

1. The malfunction is so minor that it is possible to continue driving with a replacement program while maintaining driving safety. The driver is not notified of this via the Selector Lever Transmission Range Display (Y5). The display shows the selector lever position normally. When can changes in driving behavior actually be detected.

2. Individual lever positions blink in Selector Lever Transmission Range Display (Y5). This informs the driver that this gear can presently not be selected. An example: Reverse, lever in "R" and vehicle drives backward. If "D" is engaged in this situation, the letter "D" blinks in the Selector Lever Transmission Range Display (Y5). In this case, the control module prevents 1st gear from being engaged to avoid damaging the transmission. The gear is only engaged when vehicle is stopped. If you want to test this, do so carefully!

3. The Selector Lever Transmission Range Display ( Y5) is completely lit up and blinks. The selector lever position is indicated. An example of this: Transmission oil temperature is too high. Reasons can be, among other things: Towing trailer with too large of a load, auxiliary installations on front of vehicle, "lack of cooling air".

4. Selector lever position cannot be recognized, Selector Lever Transmission Range Display (Y5) blinks, changes in driving and shift behavior can be clearly detected, reverse not possible. There is a "serious malfunction", a sub-gearbox is switched off, transmission repair is necessary.