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DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.

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HOMESERVICE MANUALSCHEVROLET2003TRAILBLAZER 4.2 S, 4WDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 1426 (WIRING SYSTEMS (COMPONENT LOCATOR))ELECTRICAL CENTER IDENTIFICATION VIEWSFUSE BLOCK - UNDERHOOD, BOTTOM VIEW

2003 Chevrolet TrailBlazer 4.2 S, 4WD

Fuse Block - Underhood, Bottom View

2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Fuse Block - Underhood, Bottom View

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2004 Oldsmobile Bravada, 2004 GMC Envoy XUV, 2004 GMC Envoy XL, 2004 GMC Envoy, and 2004 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.

Fig 1: Fuse Block - Underhood, Bottom View

Courtesy of GENERAL MOTORS CORP.

Fuse Block - Underhood C1 (4.2L)

Courtesy of GENERAL MOTORS CORP.
Connector Part Information		15319897 68-Way F Metri-Pack 280 Series Flexlock (L-GY)
Pin	Wire Color	Circuit No.	Function
A1	-	-	Not Used
A2	PK	839	Ignition 1 Voltage
A3-A4	-	-	Not Used
A5	PK	639	Ignition 1 Voltage
A6-A7	-	-	Not Used
A8	PU	6	Starter Solenoid Crank Voltage
A9	GY	1524	Backup Lamp Signal
A10	YE	1737	Neutral Safety Switch Park/Neutral Signal
A11	D-GN/WH	465	Fuel Pump Relay Control
A12	-	-	Not Used
B1	-	-	Not Used
B2	PK	239	Ignition 1 Voltage
B3-B4	-	-	Not Used
B5	PK	339	Ignition 1 Voltage
B6	L-GN	275	Park Neutral Position Switch Park Signal
B7-B8	-	-	Not Used
B9	WH	1310	EVAP Canister Vent Solenoid Control
B10	OG/BK	463	Requested Torque Signal
B11-B12	-	-	Not Used
C1	-	-	Not Used
C2	PK	539	Ignition 1 Voltage
C2	PK	539	Ignition 1 Voltage
C3-C4	-	-	Not Used
C5	PK	439	Ignition 1 Voltage
C5	PK	439	Ignition 1 Voltage
C8-C9	-	-	Not Used
C10	BK	550	Ground
C11	TN/BK	464	Delivered Torque Signal
C12	-	-	Not Used
D1	-	-	Not Used
D2	PK	1020	Ignition 0 Voltage
D3	BK	350	Ground
D3	BK	350	Ground
D4	-	-	Not Used
D5	PK	439	Ignition 1 Voltage
D5	PK	439	Ignition 1 Voltage
D8-D9	-	-	Not Used
D10	BK	550	Ground
D10	BK	550	Ground
D11	PK/BK	415	Air Sol Relay Power Output
D12	-	-	Not Used
E1-E4	-	-	Not Used
E5	PK	439	Ignition 1 Voltage
E5	PK	439	Ignition 1 Voltage
E6	BK	450	Ground
E7	BK	450	Ground
E8-E9	-	-	Not Used
E10	BK	550	Ground
E10	BK	550	Ground
E11	PU	421	Air Sol Relay Control
E12	D-GN	59	A/C Compressor Clutch Supply Voltage
F1-F2	-	-	Not Used
F3	BK	350	Ground
F4	-	-	Not Used
F5	PK	439	Ignition 1 Voltage
F5	PK	439	Ignition 1 Voltage
F6-F9	-	-	Not Used
F10	BK	550	Ground
F10	BK	550	Ground
F11-F12	-	-	Not Used

Fuse Block - Underhood C1 (5.3L)

Courtesy of GENERAL MOTORS CORP.
Connector Part Information		15319897 68-Way F Metri-Pack 280 Series Flexlock (L-GY)
Pin	Wire Color	Circuit No.	Function
A1	-	-	Not Used
A2	PK	1539	Ignition 1 Voltage
A2	PK	1539	Ignition 1 Voltage
A3-A4	-	-	Not Used
A5	PK	639	Ignition 1 Voltage
A6	PU	806	Crank Voltage
A7	OG/BK	463	Requested Torque Signal
A8	PU	6	Starter Solenoid Crank Voltage
A9	GY	1524	Backup Lamp Signal
A10	YE	1737	Neutral Safety Switch Park/Neutral Signal
A11-A12	-	-	Not Used
B1	-	-	Not Used
B2	PK	239	Ignition 1 Voltage
B2	PK	239	Ignition 1 Voltage
B3-B4	-	-	Not Used
B5	PK	339	Ignition 1 Voltage
B6	L-GN	275	Park Neutral Position Switch Park Signal
B7	-	-	Not Used
B8	D-GN/WH	465	Fuel Pump Relay Control
B9	WH	1310	EVAP Canister Vent Solenoid Control
B10	TN/BK	464	Delivered Torque Signal
B11-B12	-	-	Not Used
C1	-	-	Not Used
C2	PK	539	Ignition 1 Voltage
C2	PK	539	Ignition 1 Voltage
C3-C4	-	-	Not Used
C5	PK	439	Ignition 1 Voltage
C8-C9	-	-	Not Used
C10	BK	550	Ground
C11	-	-	Not Used
C12	PK	1339	Ignition 1 Voltage
C12	PK	1339	Ignition 1 Voltage
D1	-	-	Not Used
D2	PK	1020	Ignition 0 Voltage
D3	BK	350	Ground
D4	WH/BK	2366	Cooling Fan Clutch Control
D5-D7	-	-	Not Used
D8	YE/BK	625	Starter Enable Relay Control
D9	D-GN/WH	459	A/C Compressor Clutch Relay Control
D10	BK	550	Ground
D10	BK	550	Ground
D11	D-GN	59	A/C Compressor Clutch Supply Voltage
D12	PK	1239	Ignition 1 Voltage
D12	PK	1239	Ignition 1 Voltage
E1-E4	-	-	Not Used
E5	BK	450	Ground
E6	BK	450	Ground
E7	BK	450	Ground
E7	BK	450	Ground
E8-E11	-	-	Not Used
E12	PK	839	Ignition 1 Voltage
F1-F2	-	-	Not Used
F3	BK	350	Ground
F4-F12	-	-	Not Used

Fuse Block - Underhood C2

Courtesy of GENERAL MOTORS CORP.
Connector Part Information		15319896 68-Way F Metri-Pack 280 Series Flexlock (BK)
Pin	Wire Color	Circuit No.	Function
A1	-	-	Not Used
A2	D-GN	189	Headlamp Leveling Motor Supply Voltage (TR6)
A3	OG	57	Left Cornering Lamp Supply Voltage
A4	-	-	Not Used
A5	WH/BK	2366	Cooling Fan Clutch Control (4.2L)
A6	BN	2309	Front Park Lamps Supply Voltage
A7	OG	440	Battery Positive Voltage
A7	OG	440	Battery Positive Voltage (5.3L)
A8-A9	-	-	Not Used
A10	YE	18	Left Rear Stop/Turn Lamp Supply Voltage (UY7)
A11	OG	1640	Battery Positive Voltage (NP4/NP8)
A12	OG	2268	Windshield Washer Relay Control
B1	D-BU	2115	Right Turn Signal Lamps Supply Voltage
B2	-	-	Not Used
B3	PK/WH	1970	Headlamp Low Beam Relay Control
B4-B5	-	-	Not Used
B6	PK	639	Ignition 1 Voltage
B7	BK	58	Right Cornering Lamp Supply Voltage
B8-B9	-	-	Not Used
B10	PU	420	TCC Brake Switch/Cruise Control Release Signal
B10	PU	420	TCC Brake Switch/Cruise Control Release Signal
B11	BN	241	Ignition 3 Voltage
B12	-	-	Not Used
C1	L-BU	2114	Left Turn Signal Lamps Supply Voltage
C2	D-GN/WH	1317	Fog Lamp Relay Control
C3	L-GN	2270	Rear Window Washer Relay Control
C4	-	-	Not Used
C5	OG	3040	Battery Positive Voltage (Early Production Only)
C8	-	-	Not Used
C9	OG	1540	Battery Positive Voltage
C10	-	-	Not Used
C11	BN	441	Ignition 3 Voltage
C12	BK/WH	1969	Headlamp High Beam Relay Control
D1	D-GN/WH	1317	Fog Lamp Relay Control (T96)
D2	-	-	Not Used
D3	WH	2282	Headlamp Washer Relay Control (CE4)
D4	-	-	Not Used
D5	OG	140	Battery Positive Voltage
D8	-	-	Not Used
D9	OG	640	Battery Positive Voltage
D9	OG	640	Battery Positive Voltage
D10	D-GN	19	Right Rear Stop/Turn Lamp Supply Voltage (UY7)
D11-D12	-	-	Not Used
E1	OG	2340	Battery Positive Voltage
E2	BK	28	Horn Relay Control
E3	PK	1020	Ignition 0 Voltage
E4	-	-	Not Used
E5	PK	39	Ignition 1 Voltage
E6	OG	3240	Battery Positive Voltage (JF4)
E7	OG	3040	Battery Positive Voltage (Late Production w/JF4)
E8-E9	-	-	Not Used
E10	L-GN/BK	584	A/T Shift Lock Control Switch Supply Voltage (4.2L)
E10	L-GN/BK	584	A/T Shift Lock Control Switch Supply Voltage (4.2L)
E11	BK/WH	1695	Axle Switch Signal (NP8)
E12	OG	1140	Battery Positive Voltage
E12	OG	1140	Battery Positive Voltage (Export 4.2L Only)
F1	OG	2940	Battery Positive Voltage
F2-F4	-	-	Not Used
F5	YE	1139	Ignition 1 Voltage
F6	PU	806	Crank Voltage (4.2L)
F7	YE	5	Crank Voltage
F8	YE/BK	625	Starter Enable Relay Control (4.2L)
	L-GN/BK	584	A/T Shift Lock Control Switch Supply Voltage (5.3L)
	L-GN/BK	584	A/T Shift Lock Control Switch Supply Voltage (5.3L)
F9	-	-	Not Used
F10	D-GN	1433	Neutral Start Switch Signal (4.2L)
F11	RD	142	Battery Positive Voltage
F12	D-GN/WH	459	A/C Compressor Clutch Relay Control (4.2L)

Fuse Block - Underhood C3

Courtesy of GENERAL MOTORS CORP.
Connector Part Information		15319892 32-Way F Metri-Pack 280 Series Flexlock (NA)
Pin	Wire Color	Circuit No.	Function
A1	-	-	Not Used
A2	PK	739	Ignition 1 Voltage (SWB w/4.2L)
A3	OG	2840	Battery Positive Voltage (G67)
A4	-	-	Not Used
A5	PK	239	Ignition 1 Voltage (4.2L w/BAE)
A5	PK	239	Ignition 1 Voltage (4.2L)
A6	-	-	Not Used
B1-B3	-	-	Not Used
B4	L-GN	1624	Trailer Backup Lamps Supply Voltage
B5	BN	441	Ignition 3 Voltage
B6	-	-	Not Used
C1-C5	-	-	Not Used
C6	OG	540	Battery Positive Voltage (5.3L)
D1	-	-	Not Used
D2	YE	1618	Trailer Left Rear Turn/Stop Lamp Supply Voltage
D5	TN/BK	464	Delivered Torque Signal (2WD w/NW7)
D6	BK/WH	1695	Axle Switch Signal (NP8)
E1-E2	-	-	Not Used
E3	PU	420	TCC Brake Switch Signal
E4	BN	241	Ignition 3 Voltage
E4	BN	241	Ignition 3 Voltage (NP8)
E5	OG	1640	Battery Positive Voltage (NP8)
E6	-	-	Not Used
F1	BK	350	Ground
F1	BK	350	Ground (NP8)
F2	OG/BK	463	Requested Torque Signal (2WD w/NW7)
F3	GY	120	Fuel Pump Supply Voltage
F4	WH	1310	EVAP Canister Vent Solenoid Control
F5	-	-	Not Used
F6	D-GN	1619	Trailer Right Rear Turn/Stop Lamp Supply Voltage

Fuse Block - Underhood C4

Courtesy of GENERAL MOTORS CORP.
Connector Part Information		15319893 32-Way F Metri-Pack 280 Series Flexlock (GY)
Pin	Wire Color	Circuit No.	Function
A1	BN	2309	Front Park Lamps Supply Voltage
A1	BN	2309	Front Park Lamps Supply Voltage (Domestic Except W49)
A2	-	-	Not Used
A3	WH	2368	Cooling Fan Clutch Supply Voltage
A4-A5	-	-	Not Used
A6	L-BU	2114	Left Turn Signal Lamps Supply Voltage
A6	L-BU	2114	Left Turn Signal Lamps Supply Voltage (Except Export)
B1	BN	2309	Front Park Lamps Supply Voltage
B1	BN	2309	Front Park Lamps Supply Voltage (Domestic Except W49)
B2	PK	639	Ignition 1 Voltage (TR6)
B2	PK	639	Ignition 1 Voltage (TR6)
B3	BK	58	Right Cornering Lamp Supply Voltage
B4	OG	57	Left Cornering Lamp Supply Voltage
B5	D-GN	392	Rear Window Washer Pump Control
B6	-	-	Not Used
C1-C2	-	-	Not Used
C5	BK	350	Ground
C6	D-BU	2115	Right Turn Signal Lamps Supply Voltage
C6	D-BU	2115	Right Turn Signal Lamps Supply Voltage (Except Export)
D1-D2	-	-	Not Used
D5	D-GN	189	Headlamp Leveling Motor Supply Voltage (TR6)
D5	D-GN	189	Headlamp Leveling Motor Supply Voltage (TR6)
D6	-	-	Not Used
E1	D-GN/WH	711	Left Headlamp High Beam Supply Voltage
E2	YE	712	Left Headlamp Low Beam Supply Voltage
E3	-	-	Not Used
E4	RD	228	Windshield Washer Pump Control
E5-E6	-	-	Not Used
F1	L-GN/BK	311	Right Headlamp High Beam Supply Voltage
F2	TN/WH	312	Right Headlamp Low Beam Supply Voltage
F3	-	-	Not Used
F4	D-GN	1329	Horn Fuse Supply Voltage
F5	PU	1197	Headlamp Washer Pump Control (CE4)
F6	PU	34	Fog Lamps Supply Voltage (T96)
F6	PU	34	Fog Lamps Supply Voltage (T96)

Fuse Block - Underhood C5

Courtesy of GENERAL MOTORS CORP.
Connector Part Information		12193694 2-Way F MAXI FUSE (L-GY)
Pin	Wire Color	Circuit No.	Function
A	RD	342	Battery Positive Voltage
B	PK	3	Ignition 1 Voltage

Fuse Block - Underhood C6

Courtesy of GENERAL MOTORS CORP.
Connector Part Information		12193696 2-Way F MAXI FUSE (BN)
Pin	Wire Color	Circuit No.	Function
A	-	-	Not Used
B	RD	542	Battery Positive Voltage

Fuse Block - Underhood C7

Courtesy of GENERAL MOTORS CORP.
Connector Part Information		12193693 2-Way F MAXI FUSE (BK)
Pin	Wire Color	Circuit No.	Function
A	RD	1042	Battery Positive Voltage (SWB w/4.2L)
B	RD	642	Battery Positive Voltage

RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.
• Brakes feel soft, pull hard to one side, or make grinding noises.
• The engine overheats, stalls repeatedly, or misfires under load.
• You are missing required tools, torque specs, or safe lifting equipment.
• You are not confident in the next step or safety outcome.