GM Service Manual Online
For 1990-2009 cars only
Figure 1:

Engine Compartment Fuse/Relay Center


Object Number: 720670  Size: MF
(1)Engine Compartment Fuse/Relay Center
Figure 2:

AF Electrical Connectors


Object Number: 506026  Size: LF
(1)23-Way In-line Connector C200 Black
(2)10-Way In-line Connector C251 Natural
(3)Passthrough P001 (not shown)
(4)Data Link Connector (DLC)
(5)10-Way In-line Connector C250 Natural
(6)Fuel Gauge Selector Switch/Fuel Indicator Lamp and Panel Dimmer Switch Assembly
(7)Fuel Gauge Select Switch Connector C254
(8)Passthrough P401
(9)6-Way In-line Connector C450 Black
(10)1-Way In-line Connector C454
(11)Fuel Pressure Sensor Connector C452 Black
(12)High Pressure Lock-off Connector C453 Black
(13)Fuel Temperature Sensor Connector C451 Gray
(14)High Pressure Lock-off (HPL) with Internal Fuel Temperature Sensor (FTS)
(15)Fuel Pressure Sensor (FPS)
(16)G112
(17)Fuel Gauge Relay Connector C012
(18)Lock-off Relay Connector C011
(19)AF Fuel Pump Relay Connector C007
(20)Ignition Relay Connector C004
(21)AF Engine Control Unit
(22)AF Engine Control Unit Connector C001 Blue
(23)AF Engine Control Unit Connector C002 White/Clear
(24)10-Way In-line Connector C018 Black
(25)10-Way In-line Connector C017 Gray
(26)6-Way In-line Connector C019 Black
(27)GMS/MCV Assembly
(28)Mixture Control Valve Connector C021
(29)Gas Mass Sensor Connector C010
(30)Low Pressure Lock-off Connector C014
Figure 3:

AF Fuel System


Object Number: 506031  Size: LF
(1)CNG Fuel Outlet Line
(2)Fuel Pressure Sensor (FPS)
(3)CNG Fill Line
(4)HPL Manual Shut-off Fitting
(5)HPL Pressure Relief Device (PRD) Line
(6)High Pressure Lock-off Solenoid
(7)CNG Fill Line Vent Boot (shown disconnected)
(8)CNG Fill Valve
(9)High Pressure Regulator (HPR) Coolant Hose
(10)HPR Pressure Relief Device (PRD)
(11)High Pressure Regulator Fuel Outlet Line
(12)High Pressure Regulator (HPR)
(13)CNG Fuel Pressure Test Port
(14)Low Pressure Regulator (LPR)
(15)GMS/MCV Assembly
(16)Mixture Control Valve (MCV)
(17)Gas Mass Sensor
(18)LPR Low Pressure Hose
(19)Low Pressure Lock-off Solenoid Fuel Inlet Line
(20)Low Pressure Lock-off (LPL) Solenoid