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 2000 Pontiac Firebird, 2000 Chevrolet Corvette, and 2000 Chevrolet Camaro. However, it is still accessible from the selected car via links, so may be relevant.
- Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
- Start and operate engine at idle. Using scan tool, monitor FAILED THIS IGNITION under DTC status for DTC P1635. If DTC P1635 failed this ignition cycle, diagnose affected DTC. If DTC does not fail this ignition, go to next step.
- Turn ignition on, with engine on. Using scan tool, monitor A/C high side. If A/C high side voltage is 0.1-1.8 volts, go to next step. If A/C high side voltage is not 0.1-1.8 volts, go to step 5.
- Turn ignition on, with engine off. Review FREEZE FRAME data and note parameters. Operate vehicle within FREEZE FRAME parameters. If test indicates that this test failed this ignition cycle while operating vehicle, go to next step. If test does not indicate that this test failed this ignition cycle, see DIAGNOSTIC AIDS .
- Disconnect A/C refrigerant pressure sensor harness connector. If scan tool indicates that A/C high side voltage is less than one volt, go to next step. If A/C high side voltage is not less than one volt, go to step 10.
- Using DVOM, check voltage between A/C refrigerant pressure sensor 5-volt reference circuit and battery ground. If voltage reading is about 5 volts, go to next step. If voltage reading is not about 5 volts, go to step 11.
- Using DVOM, check voltage between A/C refrigerant pressure sensor 5-volt reference circuit and sensor ground. If voltage reading is about 5 volts, go to next step. If voltage reading is not about 5 volts, go to step 12.
- Connect a fused jumper wire between A/C refrigerant pressure sensor 5-volt reference circuit to sensor signal ground. Scan tool should read about 5 volts. If voltage is as specified, go to next step. If voltage is not as specified, go to step 13.
- Repair faulty A/C refrigerant pressure sensor connection or replace faulty sensor. After replacing sensor, go to step 14.
- Repair short to voltage in A/C refrigerant pressure sensor signal circuit. After repairs, go to step 14.
- Repair 5-volt reference circuit to pressure sensor. After replacing sensor, go to step 14.
- Repair ground circuit to pressure sensor. After replacing sensor, go to step 14.
- Repair signal circuit to pressure sensor. After replacing sensor, go to next step.
- Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2.
- Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.
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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.