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

PCM Power, Grounding, DLC, and MIL


Object Number: 786838  Size: FS
Master Electrical Component List
Powertrain Control Module Description
5 Volt and Low Reference Busses
OBD II Symbol Description Notice
ECM-B, Horn, and A/C Fuses
IGN A Fuse and Ignition Switch
ECM-I Fuse, 1 of 2, Fuel Injectors
IGN A Fuse and Ignition Switch
IP Illumination Lamps and Indicator Lamps
Gauges and Turn-B/U Fuses
IP Illumination Lamps and Indicator Lamps
Datalink Connector Schematic
G104 (L18)
L18 HO2S Circuit
Figure 2:

5 Volt and Low Reference Busses


Object Number: 786840  Size: FS
Master Electrical Component List
Powertrain Control Module Description
L18 MAP, ECT, and IAT/MAF Sensor
L18 PCM Power, Grounding, DLC, and MIL Control
OBD II Symbol Description Notice
Figure 3:

MAP, ECT, VSS Circuit, and IAT/MAF


Object Number: 786841  Size: FS
Master Electrical Component List
Powertrain Control Module Description
L18 HO2S Circuit
5 Volt and Low Reference Busses
OBD II Symbol Description Notice
IGN A Fuse and Ignition Switch
L18 EVAP and EGR Circuits
G104 (L18)
PNP Switch, Pressure Switch, TFT Sensor, PC Sol Valve, Shaft Speed Sensors
CPP Switch and VSS - L18
EBCM Stoplamp switch and Wheel Speed Inputs
Fuel Gauge, Tachometer, and Speedometer
Oil Pres, Coolant Temp, and Volt Gauges, Check Gauges and Batt Lamp
Figure 4:

HO2S Circuit


Object Number: 647035  Size: FS
Master Electrical Component List
Powertrain Control Module Description
L18 TAC Power, Grounding, Data Circuits, and Indicator Control
L18 MAP, ECT, and IAT/MAF Sensor
OBD II Symbol Description Notice
L18 PCM Power, Grounding, DLC, and MIL Control
G104 (L18)
L18 PCM Power, Grounding, DLC, and MIL Control
Figure 5:

TAC Power, Grounding, Data Circuits, and Indicator Control


Object Number: 647040  Size: FS
Master Electrical Component List
Throttle Actuator Control (TAC) System Description
L18 Throttle Control Circuits
L18 HO2S Circuit
OBD II Symbol Description Notice
IGN A Fuse and Ignition Switch
IGN-E and ENG I Fuses - Gas
G104 (L18)
IGN A Fuse and Ignition Switch
Gauges and Turn-B/U Fuses
IP Illumination Lamps and Indicator Lamps
Figure 6:

Throttle Control Circuits


Object Number: 647042  Size: FS
Master Electrical Component List
Throttle Actuator Control (TAC) System Description
L18 Accelerator Pedal Position Sensor Circuits
L18 TAC Power, Grounding, Data Circuits, and Indicator Control
OBD II Symbol Description Notice
Figure 7:

Accelerator Pedal Position Sensor Circuits


Object Number: 647044  Size: FS
Master Electrical Component List
Throttle Actuator Control (TAC) System Description
TAC Cruise Control Inputs and PTO Interfaces
L18 Throttle Control Circuits
OBD II Symbol Description Notice
Figure 8:

TAC Cruise Control Inputs


Object Number: 647045  Size: FS
Master Electrical Component List
Throttle Actuator Control (TAC) System Description
L18 PTO Control Provisions
L18 Accelerator Pedal Position Sensor Circuits
OBD II Symbol Description Notice
Stop/Haz, Radio Batt, Aux Pwr, and Cig Ltr Fuses
Lighting and Battery Fuses
ABS, Blower, Stop-Haz, and IGN B Fuses and Ignition Switch
L18 PTO Control Provisions
Brake, Cruise, SEO TP-2, and Htr-A/C Fuses
L18 PTO Control Provisions
L18 PTO Control Provisions
Stop Lamps and Turn/Hazard Lamps Controls
Figure 9:

PTO Control Provisions


Object Number: 647046  Size: FS
Master Electrical Component List
L18 Ignition Control - Bank 1 (LH)
TAC Cruise Control Inputs and PTO Interfaces
OBD II Symbol Description Notice
Battery and Underhood Fuse Block
TAC Cruise Control Inputs and PTO Interfaces
ABS, Blower, Stop-Haz, and IGN B Fuses and Ignition Switch
Instrument Lamps Dimming Circuit
Instrument Lamps Dimming Circuit
TAC Cruise Control Inputs and PTO Interfaces
TAC Cruise Control Inputs and PTO Interfaces
G200
TAC Cruise Control Inputs and PTO Interfaces
TAC Cruise Control Inputs and PTO Interfaces
G105, L18, All except Ignition Coils
Figure 10:

Ignition Control, Bank 1 (Left Side)


Object Number: 647023  Size: FS
Master Electrical Component List
Electronic Ignition (EI) System Description
L18 Ignition Control - Bank 2 (RH)
L18 PTO Control Provisions
OBD II Symbol Description Notice
IGN A Fuse and Ignition Switch
ECM-I Fuse, 2 of 2, Ignition Coils
G105, 2 of 2, Ignition Coils
Figure 11:

Ignition Control, Bank 2 (Right Side)


Object Number: 647026  Size: FS
Master Electrical Component List
Electronic Ignition (EI) System Description
L18 CMP, CKP, and KS
L18 Ignition Control - Bank 1 (LH)
OBD II Symbol Description Notice
IGN A Fuse and Ignition Switch
ECM-I Fuse, 2 of 2, Ignition Coils
G105, 2 of 2, Ignition Coils
Figure 12:

CMP, CKP, and KS


Object Number: 786842  Size: FS
Master Electrical Component List
Knock Sensor (KS) System Description
L18 Fuel Pump Controls - Single Tank
L18 Ignition Control - Bank 2 (RH)
OBD II Symbol Description Notice
Fuel Gauge, Tachometer, and Speedometer
Figure 13:

Fuel Pump Controls, Single Tank


Object Number: 786843  Size: FS
Master Electrical Component List
Fuel System Description
L18 Fuel Pump Controls - Dual Tanks
L18 CMP, CKP, and KS
OBD II Symbol Description Notice
Battery and Underhood Fuse Block
L18 PCM Power, Grounding, DLC, and MIL Control
Theft Deterrent System
Datalink Connector Schematic
Fuel Gauge, Tachometer, and Speedometer
G105, L18, All except Ignition Coils
Figure 14:

Fuel Pump Controls, Dual Tanks


Object Number: 786844  Size: FS
Master Electrical Component List
Fuel System Description
L18 Fuel Injector Controls
L18 Fuel Pump Controls - Single Tank
OBD II Symbol Description Notice
Battery and Underhood Fuse Block
L18 PCM Power, Grounding, DLC, and MIL Control
IGN A Fuse and Ignition Switch
IGN-E and ENG I Fuses - Gas
Theft Deterrent System
Datalink Connector Schematic
Fuel Gauge, Tachometer, and Speedometer
G105, L18, All except Ignition Coils
Figure 15:

Fuel Injector Controls


Object Number: 647029  Size: FS
Master Electrical Component List
Fuel System Description
L18 EVAP and EGR Circuits
L18 Fuel Pump Controls - Dual Tanks
OBD II Symbol Description Notice
IGN A Fuse and Ignition Switch
ECM-I Fuse, 1 of 2, Fuel Injectors
Figure 16:

EVAP and EGR


Object Number: 647038  Size: FS
Master Electrical Component List
Exhaust Gas Recirculation (EGR) System Description
HVAC, Generator, and ABS Signal Circuits
L18 Fuel Injector Controls
OBD II Symbol Description Notice
IGN A Fuse and Ignition Switch
L18 MAP, ECT, and IAT/MAF Sensor
Figure 17:

5 Volt and Low Reference Busses


Object Number: 786840  Size: FS
Master Electrical Component List
Powertrain Control Module Description
L18 A/T TCC/Stop Lamp Switch, Shift Solenoids
L18 EVAP and EGR Circuits
OBD II Symbol Description Notice
Air Conditioning Compressor Control (L18)
L18 Charging
Datalink Connector Schematic
EBCM Power, Grounding, DLC, and Indicator Lamps
Oil Pres, Coolant Temp, and Volt Gauges, Check Gauges and Batt Lamp
Figure 18:

A/T TCC/Stop Lamp Switch, Shift Solenoids


Object Number: 786846  Size: FS
Master Electrical Component List
Electronic Component Description
L18 A/T Internal Switches, TFT, and PC Solenoid Valve
HVAC, Generator, and ABS Signal Circuits
OBD II Symbol Description Notice
ABS, Blower, Stop-Haz, and IGN B Fuses and Ignition Switch
Brake, Cruise, SEO TP-2, and Htr-A/C Fuses
IGN A Fuse and Ignition Switch
TCC/Stoplamps Switch and Shift Solenoids
Pwr Wdos Circuit Breaker, Wiper, Radio, Crank, and Trans Fuses
TCC/Stoplamps Switch and Shift Solenoids
TCC/Stoplamps Switch and Shift Solenoids
EBCM Stoplamp switch and Wheel Speed Inputs
Figure 19:

A/T Internal Switches, TFT, PC Solenoid Valve


Object Number: 786848  Size: FS
Master Electrical Component List
Electronic Component Description
L18 A/T TCC/Stop Lamp Switch, Shift Solenoids
OBD II Symbol Description Notice
PNP Switch, Pressure Switch, TFT Sensor, PC Sol Valve, Shaft Speed Sensors
PNP Switch, Pressure Switch, TFT Sensor, PC Sol Valve, Shaft Speed Sensors
PNP Switch, Pressure Switch, TFT Sensor, PC Sol Valve, Shaft Speed Sensors
PNP Switch, Pressure Switch, TFT Sensor, PC Sol Valve, Shaft Speed Sensors
PNP Switch, Pressure Switch, TFT Sensor, PC Sol Valve, Shaft Speed Sensors
PNP Switch, Pressure Switch, TFT Sensor, PC Sol Valve, Shaft Speed Sensors
PNP Switch, Pressure Switch, TFT Sensor, PC Sol Valve, Shaft Speed Sensors