Electrical Center Identification Views. GMC Truck GMC C-Series Medium Duty Truck B7 2001

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 2001 🢒 GMC C-Series Medium Duty Truck B7 🢒 Body and Accessories 🢒 Wiring Systems 🢒 Electrical Center Identification Views

Table 1:	Fuse Block - I/P Circuit Breaker Applications
Table 2:	Fuse Block - 1 Fuse Applications
Table 3:	Fuse Block - 2 Fuse Applications
Table 4:	Relay Block #1 Relay Locations
Table 5:	Relay Block #2 Relay Locations
Table 6:	Relay Block #3 Relay Locations
Table 7:	Relay Block #4 Relay Locations
Table 8:	Relay Block #5 Circuit Breaker Applications
Table 9:	Relay Block #5 Relay Locations

Fuse Block - I/P

Fuse Block - I/P Circuit Breaker Applications

Circuit Breaker

Rating

Description

IGN 1 Circuit Breaker

10A

ABS Relay (Load) (JE5), Automatic Transmission Shift Lever, Automatic Transmission (A/T) Modulator Relay (Coil and Load) (L18 and MF1), Clutch Pedal Position (CPP) Switch (L18), Cruise Control Switch (L18), Daytime Running Lights (DRL) Control Module, DRL Relay (Coil),

Driver Information Center (DIC):

•	ABS Indicator

•	AUX BRAKE Indicator (JE3)

•	CHANGE OIL Indicator (L18)

•	CHECK TRANS Indicator (MX4/MTW)

•	DRL Indicator

•	ENGINE OVER SPEED Indicator (L18)

•	HIGH IDLE Indicator

•	INTAKE HEATER Indicator (LG5)

•	LOW AIR Indicator

•	LOW COOLANT Indicator

•	Park Brake Indicator

•	PRIMARY BRAKE Indicator

•	REDUCED ENGINE POWER Indicator (L18/MX4/MTW)

•	SERVICE ENGINE SOON Indicator

Generator (LG5), Generator Diode (D200) (LG5), Engine Hour Meter, Ignition 1 Relay (Coil), Ignition 1A Relay (Load) (L18), Ignition 1B Relay (Load) (L18), Instrument Panel Cluster (IPC):

•	CHECK GAGES Indicator

•	Check Gauges Logic

•	Engine Coolant Temperature (ECT) Gauge

•	Engine Oil Pressure (EOP) Gauge

•	Fuel Gauge

•	Generator Charge Indicator

•	Speedometer

•	Tachometer

•

Voltmeter

Multifunction Alarm Module, Powertrain Control Module (PCM)

Speedometer Adapter (LG5), Stoplamp Switch Interface Module

STOP LP Circuit Breaker

20A

Stoplamp Switch (Connector C1)

HORNS Circuit Breaker

20A

Data Link Connector (DLC)

Horn Relay (Coil and Load): Horns

ENG Circuit Breaker (L18)

20A

Evaporative Emissions (EVAP) Canister Purge Solenoid

ENG Circuit Breaker

(LG5)

20A

Ignition 1 Relay (Load):

•	Radiator Shutter Control Valve

•	Intake Air (IA) Heater (Connector C127)

ECM Circuit Breaker

(L18)

30A

Intake Air Temperature (IAT)/Mass Air Flow (MAF) Sensor, Powertrain Control Module (PCM)

ECM Circuit Breaker

(LG5)

30A

Powertrain Control Module (PCM), Transmission Control Module (TCM)

FUEL Circuit Breaker

(LG5)

20A

Ether Injector Control Valve Relay (Load):

•	Ether Injector Control Valve

•	Ether Injector Control Valve Diode (D101)

FUEL Circuit Breaker

(L18)

20A

Fuel Pump (FP) Relay (Load):

•	Engine Oil Pressure (EOP) Sensor,

•	Fuel Pump and Sender Assembly

•	Powertrain Control Module (PCM)

TL/MKR Circuit Breaker

20A

Taillamp Relay (Load):

•	Front Park/Turn Signal Lamps

•	C212 (Upfitter Connector) (Terminal A)

PNL Circuit Breaker

10A

Headlamp Switch:

•	IP Dimming Module to C212 (Upfitter Connector) (Terminal F)

•	Taillamp Relay (Coil)

HAZ Circuit Breaker

20A

Turn Signal/Hazard Flasher Module:

•	Front Turn Signal Lamps

•	Hazard Lamps

•	C212 (Upfitter Connector) (Terminal Z and L)

CHASSIS Circuit Breaker

(L18)

20A

Air Brake Dryer, Heated Moisture Ejector Valve

Rear Axle Air Shift Switch -- Two Speed (HR1/HR2), Speedometer Adapter

Rear Axle Shift Relay -- Two Speed (Coil and Load) (HPZ):

•	Rear Axle Shift Motor -- Two Speed

•	Rear Axle Driver Shift Switch -- Two Speed

CHASSIS Circuit Breaker

(LG5)

20A

Air Brake Dryer, Heated Moisture Ejector Valve

IGN 3 Circuit Breaker

10A

ABS Indicator Relay (Coil) (JE3), ABS Relay (Coil), C212 (Upfitter Connector) (Terminal V), Electronic Brake Control Module (EBCM) (JE3), Exhaust Brake Switch, Generator (L18), High Idle Switch, Ignition 3 Relay (Coil) (LG5), Transmission Fluid Temperature (TFT) Gauge

B/U Circuit Breaker

10A

Backup Lamps Switch (w/o MX4/MTW)

Park/Neutral Position (PNP) Switch (MX4/MTW)

AUX 2 Circuit Breaker

(L18)

Not Used

AUX 2 Circuit Breaker

(LG5)

20A

Rear Axle Air Shift Switch -- Two Speed (HR1/HR2), Speedometer Adapter

Rear Axle Shift Relay -- Two Speed (Coil and Load) (HPZ):

•	Rear Axle Shift Motor -- Two Speed

•	Rear Axle Driver Shift Switch -- Two Speed

ACC Circuit Breaker

10A

C212 (Upfitter Connector) (Terminal R)

BRK 1 Circuit Breaker

(JE3)

10A

Stoplamp Switch (Connector C1):

•	Power Brake (P/B) Booster Pump Motor Relay (Coil)

•	Multifunction Alarm Module

BRK 2 Circuit Breaker

(JE3)

10A

Multifunction Alarm Module

AUX 1 Circuit Breaker

(LG5)

15A

Fuel Heater

START Circuit Breaker

(L18)

10A

Clutch Switch (Manual Transmission)

Shunt to C212 (Upfitter Connector) (Terminal D) (Automatic Transmissions), Multifunction Alarm Module (L18), Neutral Safety Switch (LG5), Park/Neutral Position (PNP) Switch (LG5 and MX4/MTW), Powertrain Control Module (PCM) (L18), Starter Relay (Coil) (L18)

START Circuit Breaker

(LG5)

10A

Clutch Switch or Shunt to C212 (Upfitter Connector) (Terminal D), Engine Metal Temperature Switch, Multifunction Alarm Module, Neutral Safety Switch, Starter Relay (Coil), Starter Temperature Switch (LG5/KQR)

Fuse Block - 1

Fuse Block - 1 Fuse Applications

Fuse

Rating

Description

HORN/STOP Fuse

40A

Generator

HORNS Circuit Breaker

STOP LP Circuit Breaker

HD LP SW Fuse

30A

Headlamp Switch

IGN SW 1 Fuse

30A

Ignition Switch (Connector C1):

•	ACC Circuit Breaker

•	IGN 1 Circuit Breaker

•	START Circuit Breaker

ENGINE Fuse

(L18)

50A

Ignition 1 Relay (Load)

ENGINE Fuse

(LG5)

50A

ECM Circuit Breaker

ENG Circuit Breaker

FUEL Circuit Breaker

AUX Fuse

(L18)

40A

Ignition 1A Relay (Load):

•	ECM Circuit Breaker

•	ETM Circuit Breaker

PCM Circuit Breaker

AUX Fuse

(LG5)

40A

Ignition 3 Relay (Load)

BODY POWER 1 Fuse

50A

Junction Box -- Upfitter I/P

(BODY POWER 2 Fuse also supplies power for this load)

Fuse Block - 2

Fuse Block - 2 Fuse Applications

Fuse

Rating

Description

LIGHTING Fuse

40A

HAZ Circuit Breaker

PNL Circuit Breaker

TL/MKR Circuit Breaker

STARTER Fuse

50A

Starter Relay (Load)

IGN SW 2 Fuse

30A

Ignition Switch (Connector C2):

•	B/U Circuit Breaker

•	CHASSIS Circuit Breaker

•	IGN 3 Circuit Breaker

ABS Fuse

(JE3)

60A

Electronic Brake Control Module (EBCM)

ABS Fuse

(JE5)

30A

ABS Relay (Load):

Electronic Brake Control Module (EBCM)

PCM/INJECTORS

(L18)

30A

Ignition 1B Relay (Load):

•	EVEN INJ Circuit Breaker

•	ODD INJ Circuit Breaker

BODY POWER 2 Fuse

50A

Junction Box -- Upfitter I/P

(BODY POWER 1 Fuse also supplies power for this load)

Relay Block #1

Relay Block #1 Relay Locations

Location	Relay Name
A (L18)	Not Used
A (LG5)	Ignition 3 Relay
B	Turn Signal/Hazard Flasher Module

Relay Block #2

Relay Block #2 Relay Locations

Location	Relay Name
A	Starter Relay
B (LG5/MF1)	Automatic Transmission Modulator Relay
B (w/o LG5/MF1)	Not Used

Relay Block #3

Relay Block #3 Relay Locations

Location	Relay Name
A	Not Used
B (JE5)	ABS Relay
B (w/o JE5)	Not Used

Relay Block #4

Relay Block #4 Relay Locations

Location	Relay Name
A	Ignition 1 Relay
B	Horn Relay
C	ABS Indicator (Telltale) Relay
D	Daytime Running Lamps (DRL) Relay
E (L18)	Fuel Pump Relay
E (LG5/KTE)	Ether Injector Control Valve Relay
F	Taillamp (Lighting) Relay

Relay Block #5 (L18)

Relay Block #5 Circuit Breaker Applications

No.	Circuit Breaker	Rating	Description
1	LCT Circuit Breaker	10A	Automatic Transmission (MX4/MTW) Transmission Control Module (TCM) (MX4/MTW)
1	Not Used (w/o MX4/MTW)	--	--
2-4	Not Used	--	--
5	ETM Circuit Breaker	10A	Throttle Actuator Control (TAC) Module
6	PCM Circuit Breaker	20A	Powertrain Control Module (PCM) Transmission Control Module (TCM) (MX4/MTW)
7	EVEN INJ Circuit Breaker	15A	Ignition Coil -2, 4, 6 and 8 Fuel Injector - 2, 4, 6 and 8
8	ODD INJ Circuit Breaker	15A	Ignition Coil - 1, 3, 5 and 7 Fuel Injector - 1, 3 5 and 7

Relay Block #5 Relay Locations

Location	Relay Name
A-C	Not Used
D (MF1)	Automatic Transmission Modulator Relay
D (w/o MF1)	Not Used
E	Ignition 1A Relay
F	Ignition 1B Relay
G-K	Not Used

Diode Applications

Diode

Rating

Description

D101

(Ether Injector Diode)

(LG5)

1.0A

@ 25°C, 400 PIV, Axial

D200

(Generator Diode)

(LG5)

1.0A

@ 25°C, 400 PIV, Axial

D201

(ABS Diode)

(JE3)

1.0A

@ 25°C, 400 PIV, Axial

Fusible Link Applications

Fusible Link

Rating

Description

Fusible Link N

(LG5)

5 mm (10 GAGE)

16.1 cm (6.3 in)

long

In the engine harness, between the generator ring terminal C2 and splice S132, to the intake air (IA) heater

Fusible Link R

(JE3)

2 mm (14 GAGE)

16.1 cm (6.3 in)

long

In the positive battery cable, between the battery and splice S404, to the fuse block - I/P, BRK circuit breaker and power brake (P/B) booster pump motor relay, terminal 30

Inline Fuse Applications

Inline Fuse	Rating	Description
Generator Inline Fuse (L18)	10A	Engine Hour Meter, Multifunction Alarm Module
Generator Inline Fuse (LG5)	10A	Engine Hour Meter, Multifunction Alarm Module and Tachometer

Resistor Applications

Resistor	Value	Description
R401 (TCM/PCM Serial Data Communications Shield Resistor) (LG5/MX4/MTW)	120ohms	Metal film resistor, ±5%, ¾ watt @70° C (158° F), operating range -40° C (-40° F) to +155° C (311° F), axial
R402 (TCM/PCM Serial Data Communications Shield Resistor) (LG5/MX4/MTW)	120ohms	Metal film resistor, ±5%, ¾ watt @70° C (158° F), operating range -40° C (-40° F) to +155° C (311° F), axial