Removal, installation and checking the thermal time switch (Mercedes-Benz S-Class W126)

The thermal time switch limits the injection time of the cold start injector depending on the engine temperature. The temperature at which the thermal time switch switches is +15°C and for engines manufactured from 09.1982 - +5°C. A defective thermal time switch causes difficulties when starting the engine.



To remove the switch, you must perform the following operations:

• Disconnect the thermal switch connector and unscrew it.
• The switch hexagon is engraved with the duty cycle (12 seconds at +20°C).

To check the switch, you must perform the following operations:

• Disconnect the thermal switch connector and connect the portable lamp.
• The switch, if it was previously removed, must be pressed more tightly against the body to ensure "ground".
• Turn on the starter for up to 15 seconds. The portable lamp should light for up to 12 seconds. Otherwise, replace the thermal time switch.
• Replace the thermal time switch and connect the connector.
• Connect the green control wire to the transistor ignition system.
• Install the air filter.