FixVault

UNDERHOOD Junction Block

NOTE: Underhood junction block is located on the passenger's side of the vehicle, in front of the windshield washer fluid reservoir. See Fig 1.
Fig 1: Locating Underhood Fuse Block
G00353873Courtesy of GENERAL MOTORS CORP.
Fig 2: Identifying Underhood Fuse Block
G00353874Courtesy of GENERAL MOTORS CORP.
UNDERHOOD FUSE BLOCK CIRCUIT IDENTIFICATION (2002)

Maxi Fuse Usage
1 Coolant Fans
2 Not Used
3 Circuit Breakers: Front Comfort Controls Hi Blower, and Headlamp Fuses (Instrument Panel): Hazard and Stoplamp
4 Circuit Breaker: Power Seat. Fuses (Instrument Panel): Electronic Level Control and Rear Defogger
5 Ignition Switch to Fuses (Instrument Panel): ABS/TCS Ignition, Cruise, DRL, Electronic PRNDL, Ignition 1, PSD, Air Bag, Turn Signal and Powertrain Control Module [IGN MAIN Relay (Underhood Fuse Block A/C Clutch, Electronic Ignition, Ignition 1-U/H, INJ, TCC)1
6 Coolant Fans
7 Fuses (Instrument Panel): ABS Module Battery, Cigarette Lighter, Courtesy Lamps, Front Power Socket, Power Locks, Power Mirrors and Right Rear Power Socket
8 Ignition Switch to Fuses (I/P): Body Control Module Program, Front Comfort Controls Low/Medium Blower, Front Wiper/Washer, HVAC/DRL, MALL/Radio/DIC, Power Quarter Vent, Rear HVAC, Rear Wiper/Washer. SWC Accessory and Power Window Circuit Breaker
Mini Relays  Usage 
9 Right Fan 1, Left Fan 2 Relay
10 Left Fan 2
11 Fuses: A/C Clutch, Ignition 1 -U/H, INS, Electronic Ignition Relay, TCCRelay
12 Right Fan 1, Left Fan 2
Micro Relays  Usage 
13 A/C Clutch Relay
14 Fuel Pump Relay
15 Not Used
16 Horn Relay
17 Left Fog Lamp, Right Fog Lamp Relay, Fog Lamp Indicator
Mini Fuse  Usage 
18 Fuel Injectors 1 -6
19 Not Used
20 Not Used
21 Evaporative Emissions (EVAP) Canister Purge Valve, Heated Oxygen Sensors 1 and 2, Mass Air Flow (MAF) Sensor
22 Not Used
23 Not Used
24 Not Used
25 Ignition Control Module (ICM)
26 Not Used
27 Transaxle Range Switch to Back-up Lamps
28 A/C Clutch Relay to A/C Compressor Clutch Oil
29 Driver Information Display, Heater A/C Control, Radio, Rear Side Door Actuator Control Motor, Remote Control Door Lock Receiver (RCDLR), Security Indicator Lamp and Theft-Deterrent Shock Sensor
30 Generator
31 Automatic Transaxle (Torque Converter Clutch Solenoids) Stoplamp Switch to Powertrain Control Module
32 Fuel Pump Relay
33 Powertrain Control Module
34 Radio
35 Fog Lamp Relay
36 Horn Relay
37 Daytime Running Lamps (DRL) Control Module, Headlamps and Instrument Panel Dimmer Switch Theft-Deterrent Relay to Headlamps
38 Not Used
39 AIR
Diodes 
  Air Conditioning Clutch Diode
40 Mini Fuse Puller
UNDERHOOD FUSE BLOCK CIRCUIT IDENTIFICATION (2003-05) (1 Of 3)

Fuse Usage
1 Coolant Fans
2 Not Used
3 Circuit Breakers: Front Comfort Controls Hi Blower, and Headlamp Fuses (Instrument Panel): Hazard and Stoplamp, PASS-Key
4 Circuit Breaker: Power Seat and Power Sliding Door. Fuses (Instrument Panel): Electronic Level Control and Rear Defogger, Trailer, Fog Lamps
5 Ignition Switch to Fuses (Instrument Panel): ABS/TCS Ignition, Cruise, DRL, Electronic PRNDL, Ignition 1, AWD, PSD, Air Bag, Turn Signal and Powertrain Control Module [IGN MAIN Relay (Underhood Fuse Block: A/C Clutch, Electronic Ignition, Ignition 1-U/H, INJ, TCC)]
6 Coolant Fans
7 Fuses (Instrument Panel): ABS Module Battery, Cigarette Lighter, Courtesy Lamps, Front Power Socket, Power Locks, Power Mirrors and Right Rear Power Socket, OnStar, RAP
8 Ignition Switch to Fuses (I/P): Body Control Module Program, Front Comfort Controls Low/Medium Blower, Front Wiper/Washer, HVAC/DRL, MALL/Radio/DIC, Power Quarter Vent, Rear HVAC, Rear Wiper/Washer. SWC Accessory and Power Window Circuit Breaker, RAP
18 Fuel Injectors 1-6
19 Not Used
20 Not Used
21 Evaporative Emissions (EVAP) Canister Purge Valve, Heated Oxygen Sensors 1 and 2, Mass Air Flow (MAF) Sensor
22 Not Used
23 Not Used
24 Not Used
25 Ignition Control Module (ICM)
26 Not Used
27 Transaxle Range Switch to Back-up Lamps
28 A/C Clutch Relay to A/C Compressor Clutch Oil
29 Driver Information Display, Heater A/C Control, Radio, Rear (LH and RH) Side Door Actuator Control Motor, Remote Control Door Lock Receiver (RCDLR), Security Indicator Lamp and Theft-Deterrent Shock Sensor
30 Generator
31 Automatic Transaxle (Torque Converter Clutch Solenoids) Stoplamp Switch to Powertrain Control Module
32 Fuel Pump Relay
33 Powertrain Control Module
34 Not Used
35 Fog Lamp Relay
36 Horn Relay
37 Daytime Running Lamps (DRL) Control Module, Headlamps and Instrument Panel Dimmer Switch Theft-Deterrent Relay to Headlamps
38 Not Used
39 AIR
UNDERHOOD FUSE BLOCK CIRCUIT IDENTIFICATION (2003-05) (2 Of 3)

Fuse Usage
40 Mini Fuse Puller
  Air Conditioning Clutch Diode
UNDERHOOD FUSE BLOCK CIRCUIT IDENTIFICATION (2003-05) (3 Of 3)

Relay Usage
9 Right Fan 1, Left Fan 2
10 Left Fan 2
11 Fuses: A/C Clutch, Ignition 1-U/H, Electronic Ignition, TCC, Injectors
12 Right Fan 1, Left Fan 2
13 A/C Clutch
14 Fuel Pump
15 Not Used
16 Horn
17 Left Fog Lamp, Right Fog Lamp, Fog Lamp Indicator