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HOMESERVICE MANUALSSATURN1995SL1 AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 31 (DIAGNOSIS)ADDITIONAL SYSTEM FUNCTIONSOBD SYSTEM CHECK
1995 Saturn SL1 Automatic

OBD System Check

1995 Saturn SL1 AutomaticSECTION OBD System Check
WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 1996 Saturn SW2, 1996 Saturn SW1, 1996 Saturn SL2, 1996 Saturn SL1, and 1996 Saturn SC2. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: Scan tool is required to perform OBD system check.

The OBD System Check determines:

  • If Malfunction Indicator Light (MIL) works.
  • If PCM is operating and can recognize a fault.
  • If any codes are stored.

This is the starting point for utilizing the self-diagnostic system for determining computer-related problems. After performing necessary tests as described in the diagnostic circuit check, if no codes are indicated, problem may be intermittent. Check all applicable connections.

  1. Turn ignition off. Install scan tool and follow scan tool manufacturer's instructions to proceed with test. Turn ignition on. If scan tool displays PCM data, go to next step. If scan tool does not display PCM data, go to step 3).
  2. If DTC is present, diagnose affected DTC. If DTC is not present, observe scan tool data to determine if parameters are in correct operating range.
  3. Start engine. If engine starts, go to step 6). If engine does not start, turn ignition on. Using a test light, check PCM 1 and PCM B fuses in underhood junction block. If fuses are okay, go to next step. If fuses are faulty check and repair circuit to PCM 1 and PCM B fuses.
  4. Turn ignition off. Disconnect PCM harness connector. Turn ignition on. Check voltage between PCM harness connector circuits No. 439 (Pink wire) and No. 1140 (Orange wire). See Fig 1 If voltage is present on both circuits, go to next step. If voltage is not present on both circuits, repair open circuit between fuse block and PCM harness connector.
  5. Check PCM ground circuits. Repair as needed. If ground circuits are okay, check terminal tightness or check for faulty PCM.
  6. Using a test light, probe between Data Link Connector (DLC) terminals No. 4 and 12. If test light illuminates, go to next step. If test light does not illuminate, repair ground circuit to DLC.
  7. Check PCM circuit No. 1807 (Purple wire). If circuit is okay and vehicle is not equipped with ABS, try scan tool on another vehicle. If scan tool is okay, check for terminal tightness or faulty PCM. Repair as needed. If circuit is okay and vehicle is equipped with ABS, go to next step.
  8. Disconnect ABS controller. If scan tool now communicates with PCM, replace ABS controller.
Fig 1: Data Link Connector Circuit
G95E35711Courtesy of GENERAL MOTORS CORP.
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.