Safety Warning
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 143 (ENGINE CONTROLS - SYSTEM & COMPONENT TESTING)IDLE CONTROL SYSTEMIDLE AIR CONTROL SYSTEM DIAGNOSISDIAGNOSTIC AIDS
2003 Chevrolet TrailBlazer 4.2 S, 4WD
Diagnostic Aids
2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Diagnostic Aids
WARNING: This page does not describe the selected car, but rather 31 other vehicles, including the 2002 Saturn Vue, 2002 Pontiac Montana, 2002 Pontiac Aztek, 2002 Oldsmobile Silhouette, and 2002 Oldsmobile Bravada. However, it is still accessible from the selected car via links, so may be relevant.
Inspect for the following conditions:
- A skewed high Throttle Position (TP) sensor.
- Restricted air intake system.
- Objects blocking the IAC passage or throttle bore.
- The correct Positive Crankcase Ventilation (PCV) valve.
- A properly installed PCV valve.
- Proper operation of the PCV valve.
- Proper operation and installation of all air intake components.
- Proper installation and operation of the Mass Air Flow (MAF) sensor, if equipped.
- Evidence of damage or tampering of the following components:
- The throttle stop screw.
- The throttle plate.
- The throttle shaft.
- The throttle linkage.
- The cruise control linkage, if equipped.
- Excess deposits in the IAC passage or on the IAC pintle.
- Excess deposits in the throttle bore or on the throttle plate Vacuum leaks.
- Excess load on engine, such as energy-draining conditions of the transmission, power steering, or alternator.
- A high or unstable idle condition. This condition could be caused by a non-IAC system problem that can not be overcome by the IAC valve. See TROUBLE SHOOTING - NO CODES - TRUCKS article.
- A low or unstable idle condition. This condition could be caused by a non-IAC system problem that can not be overcome by the IAC valve. See TROUBLE SHOOTING - NO CODES - TRUCKS article.
- An intermittent condition.
RPM VARIATION LIMITS
| Engine | Maximum RPM Less Than Commanded RPM | Maximum RPM More Than Commanded RPM |
|---|---|---|
| 2.2L (A/T) | 60 | 60 |
| 2.2L (M/T) | 100 | 60 |
| 3.4L | 100 | 150 |
| 4.3L, 4.8L, 5.0L, 5.3L, 5.7L & 6.0L | 100 | 200 |
RENDER: 1.0x
NO RELATED
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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.