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HOMESERVICE MANUALSCHEVROLET2003TRAILBLAZER 4.2 S, 4WDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 131 (ENGINE CONTROLS - SENSOR OPERATING RANGE CHARTS)INTRODUCTION

2003 Chevrolet TrailBlazer 4.2 S, 4WD

Section 131 (Engine Controls - Sensor Operating Range Charts): Introduction

2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Introduction

WARNING: This page does not describe the selected car, but rather 35 other vehicles, including the 2002 Pontiac Montana, 2002 Pontiac Aztek, 2002 Oldsmobile Silhouette, 2002 Oldsmobile Bravada, and 2002 GMC Yukon XL. However, it is still accessible from the selected car via links, so may be relevant.

Sensor operating range information can help determine if a sensor is out of calibration. An out-of-calibration sensor may not set a trouble code, but may cause driveability problems.

NOTE: Unless stated otherwise in test procedure, perform all voltage tests with a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance.

ACCELERATOR PEDAL POSITION SENSOR VOLTAGE (2.2L - SATURN)

Throttle Position

⁽¹⁾ Volts

At Idle

APP Sensor No. 1

0.94

APP Sensor No. 2

4.55

Wide Open Throttle

APP Sensor No. 1

4.25

APP Sensor No. 2

2.90

⁽¹⁾	Measured at sensor or as seen on scan tool.

ACCELERATOR PEDAL POSITION SENSOR VOLTAGE (3.0L)

Throttle Position

⁽¹⁾ Volts

At Idle

APP Sensor No. 1

0.98

APP Sensor No. 2

0.49

Wide Open Throttle

APP Sensor No. 1

4.16

APP Sensor No. 2

2.08

⁽¹⁾	Measured at sensor or as seen on scan tool.

ACCELERATOR PEDAL POSITION SENSOR VOLTAGE (4.2L)

Throttle Position

⁽¹⁾ Volts

At Idle

APP Sensor No. 1

Less Than 1.1

APP Sensor No. 2

Greater Than 3.9

Wide Open Throttle

APP Sensor No. 1

Greater Than 2.0

APP Sensor No. 2

Less Than 3.0

⁽¹⁾	Measured at sensor or as seen on scan tool.

ACCELERATOR PEDAL POSITION SENSOR VOLTAGE (4.8L, 5.3L, 6.0L & 8.1L)

Throttle Position

⁽¹⁾ Volts

At Idle

APP Sensor No. 1

Less Than 1.0

APP Sensor No. 2

Greater Than 4.0

APP Sensor No. 3

Greater Than 3.8

Wide Open Throttle

APP Sensor No. 1

Greater Than 2.0

APP Sensor No. 2

Less Than 2.9

APP Sensor No. 3

Less Than 3.1

⁽¹⁾	Measured at sensor or as seen on scan tool.

ACCELERATOR PEDAL POSITION SENSOR VOLTAGE (6.5L & 6.6L)

Throttle Position

⁽¹⁾ Volts

At Idle

APP Sensor No. 1

.44-.95

APP Sensor No. 2

3.9-4.5

APP Sensor No. 3

3.6-4.1

At 2500 RPM

APP Sensor No. 1

.75-1.25

APP Sensor No. 2

3.7-4.3

APP Sensor No. 3

3.5-4.0

⁽¹⁾	Measured at sensor or as seen on scan tool.

FUEL GAUGE PULSE WIDTH MODULATION OUTPUT (CNG)

Percent Fuel ⁽¹⁾

⁽²⁾ PWM Output

100

⁽¹⁾	This is the percentage of fuel the gauge will display.

⁽²⁾	This is the PWM output required to display the percentage of fuel.

FUEL RAIL PRESSURE SENSOR OUTPUT VOLTAGE VS PRESSURE (CNG)

Psi (KPa)	Volts
0 (0)	0.5
10 (68.95)	0.9
20 (137.90)	1.3
30 (206.85)	1.7
40 (275.80)	2.1
50 (344.75)	2.5
60 (413.70)	2.9
70 (483.65)	3.3
80 (551.60)	3.7
90 (620.55)	4.1
100 (689.50)	4.5

FUEL RAIL TEMPERATURE SENSOR OUTPUT RESISTANCE VS TEMPERATURE VS VOLTAGE (CNG)

Temperature - °F (°C)	Volts	Ohms
-58 (-58)	4.97	1,579,500.00
-40 (-40)	4.93	1,070,550.00
-4 (-20)	4.74	186,000.00
32 (0)	4.24	55,620.00
50 (10)	3.81	32,100.00
68 (20)	3.29	19,185.00
77 (25)	3.00	15,000.00
86 (30)	2.71	11,818.50
95 (35)	2.42	9376.50
104 (40)	2.14	7489.50
113 (45)	1.88	6021.00
122 (50)	1.64	4870.50
140 (60)	1.23	3250.50
158 (70)	0.91	2218.50
176 (80)	0.67	1543.50
212 (100)	0.37	789.75
248 (120)	0.21	433.80
293 (145)	0.11	220.95

FUEL TANK PRESSURE SENSOR OUTPUT PRESSURE VS VOLTAGE (CNG)

Psi (KPa)	Volts
0 (0)	0.50
125 (862)	0.63
438 (3021)	0.94
750 (5172)	1.25
1063 (7331)	1.56
1375 (9483)	1.88
1688 (11,641)	2.19
2000 (13,793)	2.50
2313 (15,952)	2.81
2625 (18,103)	3.13
2938 (20,262)	3.44
3250 (22,414)	3.75
3563 (24,572)	4.06
3875 (26,724)	4.38
4000 (27,586)	4.54

FUEL TANK TEMPERATURE SENSOR RESISTANCE VS TEMPERATURE VS VOLTAGE (CNG)

Temperature - °F (°C)	Volts	Ohms
-58 (-50)	4.87	104,390
-40 (-40)	4.77	57,536
-4 (-20)	4.38	19,326
23 (-5)	3.86	9311
32 (0)	3.65	7407
41 (5)	3.42	5933
50 (10)	3.18	4764
59 (15)	2.93	3881
68 (20)	2.68	3167
77 (25)	2.43	2600
86 (30)	2.20	2148
95 (35)	1.97	1784
104 (40)	1.76	1489
113 (45)	1.57	1249
122 (50)	1.39	1052
140 (60)	1.08	758
158 (70)	0.84	556
176 (80)	0.66	414
212 (100)	0.40	240
248 (120)	0.26	147
302 (150)	0.14	77

SENSOR TEMPERATURE VS RESISTANCE (EXCEPT TRACKER)

Temperature - °F (°C)

⁽¹⁾ Ohms

302 (150)

284 (140)

266 (130)

248 (120)

100

230 (110)

132

212 (100)

177

194 (90)

241

176 (80)

332

158 (70)

467

140 (60)

667

122 (50)

973

113 (45)

1188

104 (40)

1459

95 (35)

1802

86 (30)

2238

77 (25)

2796

68 (20)

3520

59 (15)

4450

50 (10)

5670

41 (5)

7280

32 (0)

9420

23 (-5)

12,300

14 (-10)

16,180

5 (-15)

21,450

-4 (-20)

28,680

-22 (-30)

52,700

-40 (-40)

100,700

⁽¹⁾	Measure resistance across sensor terminals.

SENSOR TEMPERATURE VS RESISTANCE (TRACKER)

Temperature - °F (°C)

⁽¹⁾ Ohms

176 (80)

315

158 (70)

435

140 (60)

580

122 (50)

810

113 (45)

940

104 (40)

1150

95 (35)

1360

86 (30)

1600

77 (25)

2000

68 (20)

2400

59 (15)

3000

50 (10)

3600

41 (5)

4600

32 (0)

5700

23 (-5)

7400

14 (-10)

9800

5 (-15)

12,700

-4 (-20)

16,000

⁽¹⁾	Measure resistance across sensor terminals.

MAP SENSOR VOLTAGE

Throttle Position

⁽¹⁾ Volts

At Idle

1.0-1.5

Wide Open Throttle

4.0-4.9

⁽¹⁾	Measured at sensor or as seen on scan tool. Ensure sensor output changes instantly when intake manifold vacuum is applied and released.

THROTTLE POSITION SENSOR VOLTAGE

Throttle Position

⁽¹⁾ Volts

At Idle

Models Without Electronic Throttle Control

0.4-0.9

Models With Electronic Throttle Control

TP Sensor No. 1

4.8-4.3

TP Sensor No. 2

0.4-0.9

Wide Open Throttle

Models Without ElectronicThrottle Control

Greater Than 4.0

Models With Electronic Throttle Control

TP Sensor No. 1

Less Than 1.0

TP Sensor No. 2

Greater Than 3.5

⁽¹⁾	Measured at sensor or as seen on scan tool.

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.