Checking Number Of Relay Activations For Electrically Heated Windows

Checking number of relay activations for electrically heated windows

Checking number of relay activations for electrically heated windows
This fault tracing can be used to check the following relays in the central electronic module (CEM):

Note! The fault tracing applies to vehicles built after structure week 201206.

- Heated windscreen: Relay R1 and R2. The fuse box is in the engine compartment.
- Heated rear window: Relay RA1. The fuse box is in the cargo compartment.
For certain vehicles the heated windscreen and rear window functions can be temporarily deactivated for take-off and hard acceleration in order to enable the use of more engine torque for acceleration. Deactivation occurs by means of the engine control module (ECM) sending the information to the central electronic module (CEM) to open the relays for the heated windows.
After a certain number of activations the relays should be replaced. The automatic deactivation during hard acceleration will then not take place until new relays are in place. The vehicle's acceleration characteristics may thus be slightly reduced.

Note! The heated windscreen and rear window functions will continue to work, even if the automatic deactivation of these functions during hard acceleration is switched off. The heated windows can still be activated and deactivated manually.

Follow the instructions below in order to check whether the relays need replacing.
- Click on the VCT2000 symbol.
- Read out the number of relay activations.
- If the number of relay activations exceeds 300 000, replace the relay in question.





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