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
- Perform powertrain diagnostic system check. See POWERTRAIN DIAGNOSTIC SYSTEM CHECK (GASOLINE) under SELF-DIAGNOSTIC SYSTEM. After performing powertrain diagnostic system check, go to next step.
- Install scan tool. Turn ignition on, engine off. Observe TP sensor voltage on scan tool. If scan tool displays TP voltage less than 0.90 volt when throttle is fully closed, go to next step. If scan tool does not display TP voltage less than 0.90 volt, go to step 4 .
- Select TP ANGLE parameter on scan tool. Monitor scan tool while slowly depressing accelerator pedal to floor, then slowly release pedal. Repeat procedure several times. If TP angle value increases steadily when accelerator pedal is depressed to more than 98 percent and decrease steadily, returning to less than one percent when pedal is released, go to step 5 . If TP angle value does not increases steadily when accelerator pedal is depressed to more than 98 percent or does not decrease steadily, returning to less than one percent when pedal is released, go to step 17 .
- Check throttle body for binding linkage or damaged linkage. If problem was found, repair as necessary. After repairs, go to step 34 . If problem was not found, go to step 17 .
- Compare BARO reading with known good vehicle. BARO value should be within one in. Hg of other vehicle. If BARO reading is normal for your altitude, go to next step. If BARO reading is not normal for your altitude, go to step 9 .
- Start engine while watching MAP sensor value with scan tool. If MAP sensor value changes while starting engine, go to next step. If MAP sensor value does not change while starting engine, go to step 8 .
- With engine running, snap throttle while watching MAP sensor display on scan tool. If MAP sensor value changes rapidly when throttle position changes, see DIAGNOSTIC AIDS . If MAP sensor value does not change rapidly when throttle position changes, go to next step.
- Turn ignition off. Remove MAP sensor from vacuum source. See Figure or Figure . Inspect port for vacuum restrictions and vacuum leaks. If problem was found, repair as necessary. After repairs, go to step 34 . If problem was not found, go to next step.
- Turn ignition off. Disconnect MAP sensor electrical connector. Turn ignition on. Observe MAP sensor voltage on scan tool. If scan tool indicates near zero volts, go to next step. If scan tool does not indicate near zero volts, go to step 12 .
- Using test light connected to ground, probe MAP sensor connector terminal "C" (Brown wire on "N" body or Gray wire on "J" body). See Figure . If test light is on, go to next step. If test light is off, go to step 14 .
- Connect fused jumper wire (3-amp) between MAP sensor connector terminals "C" (Brown wire on "N" body or Gray wire on "J" body) and "B" (Light Green wire). If scan tool indicates voltage near 5 volts, go to step 13 . If scan tool does not indicate voltage near 5 volts, go to step 15 .
- Check Light Green wire between MAP sensor and PCM for short to voltage. If problem was found, repair as necessary. After repairs, go to step 34 . If problem was not found, go to step 30 .
- Using test light connected to battery voltage, probe MAP sensor connector terminal "A" (Orange/Black wire on "N" body or Black/White wire on "J" body). If test light is on, go to step 28 . If test light is off, go to step 16 .
- Check Brown wire on "N" body or Gray wire on "J" body between MAP sensor and PCM for high resistance. If problem was found, repair as necessary. After repairs, go to step 34 . If problem was not found, go to step 30 .
- Check Light Green wire between MAP sensor and PCM for high resistance. If problem was found, repair as necessary. After repairs, go to step 34 . If problem was not found, go to step 30 .
- Check Orange/Black wire on "N" body or Black/White wire on "J" body between MAP sensor and PCM for high resistance. If problem was found, repair as necessary. After repairs, go to step 34 . If problem was not found, go to step 30 .
- Turn ignition off. Disconnect TP sensor electrical connector. See Figure or Figure . Turn ignition on. Observe TP sensor voltage on scan tool. If scan tool indicates voltage is near zero volt, go to next step. If scan tool does not indicate voltage is near zero volt, go to step 21 .
- Using test light connected to ground, probe TP sensor connector terminal "A" (Gray wire on "J" body or Gray/Black wire on "N" body). See Figure . If test light is on, go to next step. If test light is off, go to step 23 .
- Using DVOM, measure voltage between TP sensor connector terminal "A" (Gray wire on "J" body or Gray/Black wire on "N" body) and ground. If voltage is more than 5.2 volts, go to step 24 . If voltage is not more than 5.2 volts, go to next step.
- Connect fused jumper wire (3-amp) between TP sensor connector terminals "A" (Gray wire on "J" body or Gray/Black wire on "N" body) and "C" (Dark Blue wire). If scan tool indicates voltage is near 5 volts, go to step 22 . If scan tool does not indicate voltage is near 5 volts, go to step 25 .
- Check Dark Blue wire between TP sensor and PCM for short to voltage. If problem was found, repair as necessary. After repairs, go to step 34 . If problem was not found, go to step 30 .
- Using test light connected to battery voltage, probe TP sensor connector "B" (Black wire) at TP sensor connector. If test light is on, go to step 29 . If test light is off, go to step 26 .
- Check Gray wire on "J" body or Gray/Black wire on "N" body between TP sensor and PCM for high resistance. If problem was found, repair as necessary. After repairs, go to step 34 . If problem was not found, go to step 30 .
- Check Gray wire on "J" body or Gray/Black wire on "N" body between TP sensor and PCM for short to voltage. If problem was found, repair as necessary. After repairs, go to step 34 . If problem was not found, go to step 27 .
- Check Dark Blue wire between TP sensor and PCM for high resistance. If problem was found, repair as necessary. After repairs, go to step 34 . If problem was not found, go to step 30 .
- Check TP sensor Black wire for high resistance. If problem was found, repair as necessary. After repairs, go to step 34 . If problem was not found, go to step 30 .
- Check A/C high side pressure sensor connector terminal "B" (Gray wire) and Fuel Tank Pressure (FTP) sensor connector terminal "C" (Gray wire) for short to voltage. See Figure and Figure . If problem was found, repair as necessary. After repairs, go to step 34 . If problem was not found, go to step 30 .
- Check MAP sensor connector for poor connections. If problem was found, repair as necessary. After repairs, go to step 34 . If problem was not found, go to step 31 .
- Check TP sensor connector for poor connections. If problem was found, repair as necessary. After repairs, go to step 34 . If problem was not found, go to step 32 .
- Check PCM connectors for poor connections. If problem was found, repair as necessary. After repairs, go to step 34 . If problem was not found, go to step 33 .
- Replace MAP sensor. After repairs, go to step 34 .
- Replace TP sensor. See THROTTLE POSITION SENSOR in appropriate REMOVAL, OVERHAUL & INSTALLATION article. After repairs, go to step 35 .
- Replace PCM. See POWERTRAIN CONTROL MODULE in appropriate REMOVAL, OVERHAUL & INSTALLATION article. After repairs, go to step 35 .
- Using scan tool, perform FUEL TRIM RESET procedure. After repairs, go to step 36 .
- Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within code enable criteria. If scan tool indicates diagnostic ran and passed, system is okay.
- Using scan tool, observe stored information. If any DTCs are displayed that have not been diagnosed, see DIAGNOSTIC TROUBLE CODE DEFINITIONS .
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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.