In addition to your vehicle's regular cooling system, your vehicle is also equipped with a cooling system for the SGCM system. This system is serviced differently than the vehicle's main cooling system. The SGCM cooling system includes the SGCM coolant surge tank, SGCM surge tank pressure cap, SGCM cooling pump and the Starter Generator Control Module (SGCM). The SGCM cooling system uses the same type of coolant as the vehicle's regular cooling system, but the two systems operate separately and independently. See "Engine Coolant" and "Cooling System" in the Index of the owner's manual for more information.

When you decide it is safe to lift the hood, here is what you will see:

1. 
   
   

   SGCM Coolant Pressure Tank Cap

2. Starter Generator Control Module (SGCM)

3. SGCM Cooling Hoses

4. SGCM Coolant Surge Tank

5. Engine Coolant Surge Tank and Pressure Cap

6. SGCM Cooling Pump (Out of View)

If the coolant inside the SGCM coolant surge tank is boiling, do not do anything else until it cools down.

The coolant level should be at or above the FULL COLD mark with the vehicle parked on a level surface. If it is not, you may have a leak at the SGCM heat transfer core, SGCM pressure cap, SGCM auxiliary radiator hoses, SGCM cooling pump or somewhere else in the SGCM cooling system.

Notice: Running the engine when there is a leak in the hybrid cooling system can cause the hybrid cooling system to lose all coolant and can damage the system. Get any leak fixed before you drive the vehicle or run the engine.

If you have not found a problem yet, check to see if coolant is visible in the SGCM coolant surge tank. If coolant is visible and within one inch (2.54 cm) of the FULL COLD mark, add a 50/50 mixture of clean, drinkable water and DEX-COOL® coolant at the SGCM coolant surge tank, but be sure the SGCM cooling system, including the SGCM coolant surge tank pressure cap, is cool before you do it. Use the procedure following.

Caution: Steam and scalding liquids from a hot cooling system can blow out and burn you badly. They are under pressure, and if you turn the coolant surge tank pressure cap -- even a little -- they can come out at high speed. Never turn the cap when the cooling system, including the coolant surge tank pressure cap, is hot. Wait for the cooling system and coolant surge tank pressure cap to cool if you ever have to turn the pressure cap.

Notice: Using coolant other than DEX-COOL may damage your vehicle. Any repairs would not be covered by your warranty. Always use DEX-COOL (silicate-free) coolant in your vehicle.

Caution: You can be burned if you spill coolant on hot engine parts. Coolant contains ethylene glycol and it will burn if the engine parts are hot enough. Do not spill coolant on a hot engine.

If the SGCM coolant is more than one inch (2.54 cm) below the FULL COLD mark, your vehicle must be serviced by your dealer and a special fill procedure must be followed.

Notice: Attempting to fill the hybrid cooling surge tank yourself when the fluid level is more than 1 inch (2.54 cm) below the FULL COLD mark can damage your vehicle. Your vehicle must be serviced.

1. Park the vehicle on a level surface and turn the vehicle off. You can remove the SGCM coolant surge tank pressure cap when the SGCM cooling system, including the SGCM coolant surge tank pressure cap and SGCM cooling hoses, are no longer hot. Turn the SGCM coolant surge tank pressure cap slowly counterclockwise (left) about one full turn. Wait 30 seconds.



2. Then keep turning the SGCM coolant surge tank pressure cap slowly, and remove it.
3. Add the proper coolant mixture to the SGCM coolant surge tank until the level reaches the FULL COLD mark.




Then replace the SGCM coolant surge tank pressure cap. Be sure the pressure cap is hand-tight and fully seated.

Notice: Using cooling system sealers or conditioners in an attempt to stop coolant leaks can damage the SGCM and engine cooling systems. Never use cooling system sealers or conditioners in your cooling system.