GM Service Manual Online
For 1990-2009 cars only

The high pressure regulator (HPR) is supplied with engine coolant in order to prevent internal freezing during normal operation. The HPR inlet hose connects to the Y fitting in the heater inlet hose. The HPR outlet hose connects to the Y fitting in the heater outlet hose. Both hoses are routed behind the engine and secured to the bulkhead with hose clamps. The hoses are then routed down the transmission tunnel to the HPR. The inlet hose is connected to the lower HPR fitting.