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 MANUALSCHEVROLET1999CAVALIER Z24, 2D CONVERTIBLE, AUTOMATICREPAIR AND DIAGNOSISBODY & FRAMEBODY, CAB CONTROL SYSTEMSMULTIFUNCTION ALARM MODULESYSTEM TESTSSCAN TOOL DOES NOT COMMUNICATE WITH UART DATA LINE
1999 Chevrolet Cavalier Z24, 2D Convertible, Automatic
Scan Tool Does Not Communicate With UART Data Line
1999 Chevrolet Cavalier Z24, 2D Convertible, AutomaticSECTION Scan Tool Does Not Communicate With UART Data Line
NOTE:
Short to ground will cause fuse to module power feed to blow. Before performing diagnostic procedure, check for blown fuse for module. See appropriate wiring diagram in POWER DISTRIBUTION article in WIRING DIAGRAMS.
- Remove scan tool from Data Link Connector (DLC). Disconnect Powertrain Control Module (PCM) connector. Check for open or short to ground in power feed circuits to PCM. See appropriate wiring diagram in POWER DISTRIBUTION article in WIRING DIAGRAMS. If faulty circuit was found and repaired, go to DATA LINK COMMUNICATIONS DIAGNOSTIC SYSTEM CHECK . If circuit is okay, go to next step.
- Check for open in ground circuit of PCM. See appropriate wiring diagram in GROUND DISTRIBUTION article in WIRING DIAGRAMS. If faulty circuit was found and repaired, go to DATA LINK COMMUNICATIONS DIAGNOSTIC SYSTEM CHECK . If circuit is okay, go to next step.
- Check for open, short to ground or short to open in Tan wire between PCM connector C1 terminal No. 14 and DLC terminal No. 9. See appropriate wiring diagram in DATA LINK CONNECTORS article in WIRING DIAGRAMS. If faulty circuit was found and repaired, go to DATA LINK COMMUNICATIONS DIAGNOSTIC SYSTEM CHECK . If circuit is okay, go to next step.
- Replace PCM. See appropriate REMOVAL, OVERHAUL & REPLACEMENT - CARS article in ENGINE PERFORMANCE. After repairs, go to DATA LINK COMMUNICATIONS DIAGNOSTIC SYSTEM CHECK .
RENDER: 1.0x
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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.