Display Field No. 4
WARNING: This page is about a different car, the 2003 Volkswagen EuroVan and 2002 Volkswagen EuroVan. However, it is still accessible from the selected car via links, so may be relevant.
Turn ignition on. Display should show a "1". Operate auxiliary water heater. Display should show "0". Check Black/Yellow wire to terminal No. 20 of CCM 28-pin harness connector "A" for open or short to ground.