Relays on the Model 91 Porsche 928 Cars Porsche 928S Model 91 Relay Chart Relay Number Function I - II Rear Window Heater III Daytime Running Light IV Fog Light V Starter VI Not Used VII Headlight Cleaning System VIII Fog Light IX Additional Fluid Cleaning Pump X Supply XI Wiper Intermittent Control XII Fresh Air Blower XIII Flasher XIV Defroster XV ABS XVI Horns XVII Kickdown XVIII Backup Light, Mirrors XIX ECU XX Not Used XXI Suppressor XXII EZK XXIII - XXIV Light Combination Relay XXV LH-Jetronic XXVI Fuel Pump