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 MANUALSOLDSMOBILE1998ACHIEVA 3.1 M, 4T40E/MN4REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 10 (ENGINE CONTROLS - BASIC ENGINE TESTING - 3.1L)ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECKDLC DIAGNOSIS OR NO SCAN TOOL DATA
1998 Oldsmobile Achieva 3.1 M, 4T40E/MN4
DLC Diagnosis Or No Scan Tool Data
1998 Oldsmobile Achieva 3.1 M, 4T40E/MN4SECTION DLC Diagnosis Or No Scan Tool Data
WARNING: This page does not describe the selected car, but rather 10 other vehicles, including the 1997 Pontiac Grand Prix, 1997 Pontiac Grand Am, 1997 Oldsmobile Cutlass Supreme, 1997 Oldsmobile Cutlass, and 1997 Oldsmobile Achieva. 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 . After performing OBD system check, go to next step.
- Turn ignition on with engine off. Connect a test light between DLC battery feed circuit and ground circuit. See the WIRING DIAGRAMS article. If test light illuminates, go to step 4). If test light does not illuminate, go to next step.
- Using a test light connected to ground, probe DLC battery feed circuit. See the WIRING DIAGRAMS article. If test light illuminates, go to next step 9). If test light does not illuminate, go to step 10).
- Turn ignition on with engine off. Using DVOM connected to ground, probe DLC class 2 serial data circuit. See the WIRING DIAGRAMS article. DVOM should read zero volts. If voltage is as specified, go to next step. If voltage is not as specified, go to step 7).
- Turn ignition off. Disconnect PCM connector. Turn ignition on with engine off. Using DVOM connected to battery voltage, probe DLC class 2 serial data circuit. See the WIRING DIAGRAMS article. DVOM should read zero volts. If voltage is as specified, go to next step. If voltage is not as specified, go to step 8).
- Check for open in class 2 serial data circuit between DLC and PCM. Repair as necessary. After repairs, perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK . If circuit is okay, go to step 11).
- Check for short to voltage in class 2 serial data circuit. Repair as necessary. After repairs, perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK . If circuit is okay, go to step 11).
- Locate and repair short to ground in class 2 serial data circuit. After repairs, perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK .
- Locate and repair open in DLC ground circuits. After repairs, perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK .
- Locate and repair open or short to ground in DLC battery feed circuit. After repairs, perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK .
- Replace PCM. Perform PCM relearn procedures. After repairs, perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK .
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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.