Checking 17°C (63°F) Temperature Switch

Remove connector from relay box and connect test lamp to terminals 6 and 8 (All models except 300 SEL/8 6.3 & 600), connect test lamp to terminals 6 and 2 (300 SEL/8 6.3 & 600). Turn on ignition, test lamp should light up only below 17°C (63°F) cooling water temperature.