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.
Diagnostic Procedures
2001 Chevrolet Cavalier LS, 2.4 TSECTION Diagnostic Procedures
WARNING: This page is about a different car, the 2002 Pontiac Sunfire and 2002 Chevrolet Cavalier. However, it is still accessible from the selected car via links, so may be relevant.
- Perform diagnostic system check - engine controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM. After performing diagnostic system check - engine controls, go to next step.
- Install a scan tool. Turn ignition on, with engine off. Observe the TP sensor voltage on the scan tool. Does the scan tool display a TP voltage less than 0.90 volt when the throttle is fully closed? If yes, go to next step. If no, go to step 4 .
- Select the TP angle parameter on the scan tool. Monitor the scan tool while slowly depressing the accelerator pedal to the floor, then slowly release the pedal. Repeat procedure several times. Does the TP angle value increase steadily when the accelerator pedal is depressed to more than 98 percent and decrease steadily, returning to less than 1 percent when the pedal is released? If yes, go to step 5 . If no, go to step 17 .
- Check the throttle body for binding linkage or damaged linkage Did you find and correct the condition? If yes, go to step 34 . If no, go to step 17 .
- Observe the Manifold Absolute Pressure (MAP) sensor pressure with a scan tool. Compare this value to a value observed from a known-good vehicle. Is the difference between the MAP values less than 3 kPa? If yes, go to next step. If no, go to step 9 .
- Start the engine while watching the MAP sensor value with the scan tool. Does the MAP sensor value change while starting the engine? If yes, go to next step. If no, go to step 8 .
- With the engine running, snap the throttle while watching the MAP sensor display on the scan tool. Does the MAP sensor value change rapidly when the throttle position changes? If yes, go to DIAGNOSTIC AIDS . If no, go to next step.
- Turn ignition off. Remove the MAP sensor from the vacuum source. Inspect the port for vacuum restrictions or vacuum leaks. Did you find and correct the condition? If yes, go to step 34 . If no, go to next step.
- Turn ignition off. Disconnect the MAP sensor electrical connector. Turn ON the ignition. Observe the MAP sensor voltage on the scan tool. Does the scan tool indicate that the voltage is about 0 V? If yes, go to next step. If no, go to step 12 .
- Connect a test light to a good ground. Probe the 5-volt reference circuit of the MAP sensor with the test light. Does the test light illuminate? If yes, go to next step. If no, go to step 14 .
- Connect a 3-amp fused jumper to the MAP sensor 5-volt reference circuit. Connect the other end of the 3-amp fused jumper to the MAP sensor signal circuit. Does the scan tool indicate that the voltage is about 5 V? If yes, go to step 13 . If no, go to step 15 .
- Test the MAP sensor signal circuit for a short to voltage. Did you find and correct the condition? If yes, go to step 34 . If no, go to step 30 .
- Connect a test light to B+. Probe the MAP sensor low reference circuit with the test light. Does the test light illuminate? If yes, go to step 28 . If no, go to step 16 .
- Test the 5-volt reference circuit of the MAP sensor for high resistance. Did you find and correct the condition? If yes, go to step 34 . If no, go to step 30 .
- Test signal circuit of MAP sensor for high resistance. Did you find and correct the condition? If yes, go to step 34 . If no, go to step 30 .
- Test MAP sensor low reference circuit for high resistance. Did you find and correct the condition? If yes, go to step 34 . If no, go to step 30 .
- Turn ignition off. Disconnect the TP sensor electrical connector. Turn ON the ignition. Observe the TP sensor voltage on the scan tool. Does the scan tool indicate that the voltage is about 0 V? If yes, go to next step. If no, go to step 21 .
- Connect a test light to a good ground. Probe the 5-volt reference circuit of the TP sensor with the test light. Does the test light illuminate? If yes, go to next step. If no, go to step 23 .
- Measure the voltage from the TP sensor 5-volt reference circuit to a good ground. Does the voltage measure more than 5.2 V? If yes, go to step 24 . If no, go to next step.
- Connect a 3-amp fused jumper to the TP sensor 5-volt reference circuit. Connect the other end of the 3-amp fused jumper to the TP sensor signal circuit. Does the scan tool indicate that the voltage is about 5 V? If yes, go to step 22 . If no, go to step 25 .
- Test the TP sensor signal circuit for a short to voltage. Did you find and correct the condition? If yes, go to step 34 . If no, go to step 30 .
- Connect a test light to B+. Probe the TP sensor low reference circuit at the TP sensor electrical connector with the test light. Does the test light illuminate? If yes, go to step 29 . If no, go to step 26 .
- Test the 5-volt reference circuit of the TP sensor for high resistance. Did you find and correct the condition? If yes, go to step 34 . If no, go to step 30 .
- Test the 5-volt reference circuit of the TP sensor for a short to voltage. Did you find and correct the condition? If yes, go to step 34 . If no, go to step 27 .
- Test the TP sensor signal circuit for high resistance. Did you find and correct the condition? If yes, go to step 34 . If no, go to step 30 .
- Test the TP sensor low reference circuit for high resistance. Did you find and correct the condition? If yes, go to step 34 . If no, go to step 30 .
- Test for short to voltage in the 5-volt reference circuit of the A/C high side pressure sensor and Fuel Tank Pressure (FTP) sensor. Did you find and correct the condition? If yes, go to step 34 . If no, go to step 30 .
- Inspect for poor connections at the MAP sensor. Did you find and correct the condition? If yes, go to step 34 . If no, go to step 31 .
- Inspect for poor connections at the TP sensor electrical connector. Did you find and correct the condition? If yes, go to step 34 . If no, go to step 32 .
- Inspect for poor connections at the PCM. Did you find and correct the condition? If yes, go to step 34 . If no, go to step 33 .
- Replace MAP sensor. When complete, go to step 34 .
- Replace TP sensor. When complete, go to step 34 .
- Turn ignition off. Replace PCM. Perform PCM relearn procedure. See POWERTRAIN CONTROL MODULE under PROGRAMMING. After replacing PCM, go to next step.
- Use the scan tool in order to perform the Fuel Trim Reset procedure. When complete, go to next step.
- Use the scan tool in order to clear the DTCs. Turn ignition off for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running the DTC. See CONDITIONS FOR RUNNING DTC . Does the DTC run and pass? If yes, go to next step. If no, go to step 2 .
- Using scan tool, observe stored information and Capture Info. Does the scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.
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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.