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 2003 Chevrolet Corvette. However, it is still accessible from the selected car via links, so may be relevant.
- Did you perform the Diagnostic System Check-Engine Controls? If yes, go to next step. If no, see DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM.
- Turn ignition ON, with engine OFF. With a scan tool, observe the APP sensor 3 voltage parameter. Is APP sensor 3 voltage 3.29-4.28 V? If yes, go to next step. If no, go to step 6.
- Fully depress the accelerator pedal to the Wide Open Throttle (WOT) position. Is APP sensor 3 voltage 1.63-3.1 V? If yes, go to next step. If no, go to step 6.
- Turn OFF the ignition for 15 seconds. Turn ignition ON, with engine OFF. With a scan tool, observe the Diagnostic Trouble Code (DTC) option. Lightly touch and move the related engine wiring harnesses and connectors for the APP sensor while monitoring the DTC info status. Does this DTC fail this ignition cycle during the above test? If yes, go to step 20. If no, go to next step.
- Slowly depress the accelerator pedal to WOT and then slowly return the pedal to the released position. Did this DTC fail this ignition cycle during the above test? If yes, go to step 21. If no, see DIAGNOSTIC AIDS .
- Disconnect the APP sensor harness connector. Test the APP sensor 3 signal circuit for voltage. Is APP sensor 3 signal voltage 3.94-6.06 V? If yes, go to step 11. If no, go to next step.
- Turn ignition OFF. Disconnect the TAC module harness connector containing the APP sensor circuits. Turn ignition ON, with engine OFF. Test the APP sensor 3 signal circuit for a short to voltage. Did you find and correct the condition? If yes, go to step 25. If no, go to next step.
- Test the APP sensor 3 signal circuit for an open or high resistance. Did you find and correct the condition? If yes, go to step 25. If no, go to next step.
- Test the APP sensor 3 signal circuit for a short to ground. Did you find and correct the condition? If yes, go to step 25. If no, go to next step.
- Disconnect the other TAC module harness connector. Test for a short between the APP sensor 3 signal circuit and all other TAC module circuits. Did you find and correct the condition? If yes, go to step 25. If no, go to step 23.
- Test the APP sensor 3, 5-volt reference circuit for voltage. Is voltage 3.94-6.06 V? If yes, go to step 16. If no, go to next step.
- Turn ignition OFF. Disconnect the TAC module harness connector containing the APP sensor circuits. Turn ignition ON, with engine OFF. Test the APP sensor 3, 5-volt reference circuit for a short to voltage. Did you find and correct the condition? If yes, go to step 25. If no, go to next step.
- Test the APP sensor 3, 5-volt reference circuit for an open or high resistance. Did you find and correct the condition? If yes, go to step 25. If no, go to next step.
- Test the APP sensor 3, 5-volt reference circuit for a short to ground. Did you find and correct the condition? If yes, go to step 25. If no, go to next step.
- Test for a short between the APP sensor 3, 5-volt reference circuit and all other TAC module circuits. Did you find and correct the condition? If yes, go to step 25. If no, go to step 23.
- Measure resistance between the APP sensor 3 low-reference circuit and the APP sensor 1 low-reference circuit. Is resistance is 0-5 ohms? If yes, go to step 18. If no, go to next step.
- Turn ignition OFF. Disconnect the TAC module harness connector containing the APP sensor circuits. Test the APP sensor 3 low-reference circuit for an open or high resistance. Did you find and correct the condition? If yes, go to step 25. If no, go to step 23.
- With a scan tool, observe the APP sensor 3 voltage parameter. Connect a fused jumper between the APP sensor 3 signal circuit and the APP sensor 3 low-reference circuit at the APP sensor harness connector. Is APP sensor 3 voltage at 0 V? If yes, go to next step. If no, go to step 24.
- Turn ignition OFF. Disconnect the TAC module. Test for a short between the APP sensor 3 signal circuit and all other TAC module circuits. Did you find and correct the condition? If yes, go to step 25. If no, go to step 21.
- Repair the intermittent connection as necessary. Did you complete the repair? If yes, go to step 25.
- Test for an intermittent and/or poor connections at the APP sensor. Did you find and correct the condition? If yes, go to step 25. If no, go to next step.
- Replace APP sensor. See ACCELERATOR PEDAL POSITION SENSOR under SENSORS in REMOVAL & INSTALLATION - CORVETTE article. Did you complete the replacement? If yes, go to step 25.
- Test for an intermittent and/or poor connections at the TAC module. Did you find and correct the condition? If yes, go to step 25. If no, go to next step.
- Replace TAC module. See THROTTLE ACTUATOR CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in REMOVAL & INSTALLATION - CORVETTE article. Did you complete the replacement? If yes, go to next step. Did you complete the replacement? If yes, go to next step.
- Clear the DTCs with a scan tool. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running DTC. Does the DTC run and pass? If yes, go to next step. If no, go to step 2.
- Observe the stored information, Capture Info with a scan tool. Does the scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.
NOTE:
If DTCs P1220 or P1518 is also set, see DTC P1220: THROTTLE POSITION SENSOR 2 - VOLTAGE OUT OF RANGE or DTC P1518: TAC MODULE SERIAL DATA FAULT
. Diagnose the applicable DTC first.
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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.