Tech - Service Engine Soon Lamp Illuminated/DTCs P0230,P0748,P1689 Stored

Some customers may comment that the Service Engine Soon Lamp is on. If DTC's P0230 and P0748 or P1689 are found in the PCM as a history code and normal Service Manual diagnostics do not lead to a correction, perform the following.

To perform this repair you will need the following:

Important: This repair should only be performed on vehicles built prior to the following VIN breakpoints:

1. Prep vehicle.
2. Open hood.
3. Install seat and fender covers.
4. Remove the rear seat cushion.

Caution: Before servicing any electrical component, the ignition key must be in the OFF or LOCK position and all electrical loads must be OFF, unless instructed otherwise in these procedures. If a tool or equipment could easily come in contact with a live exposed electrical terminal, also disconnect the negative battery cable. Failure to follow these precautions may cause personal injury and/or damage to the vehicle or its components.

5. Disconnect the negative battery cable from the battery.
6. Disconnect the intake air temperature sensor wire.
7. Disconnect the fresh air intake duct from the throttle body.
8. Remove the two (2) screws which retain the air cleaner assembly cover. Set the cover and air duct to the side.
9. Remove the air cleaner filter element.
10. Disconnect both wiring harness connectors from the Powertrain Control Module (PCM).
11. Locate the blue (J1) connector for the PCM wiring harness. Remove the Connector Position Assurance (CPA) from the connector. Cut the plastic tie straps holding the cover to the back of the blue connector and remove the cover.
12. Using a seam ripper or other suitable tool, cut and remove the tape from around the wiring harness for a distance of about 254 mm (10 in) from the PCM connector. This will open the wiring from the PCM connector to the convoluted tubing surrounding the wiring harness.
13. Locate the black/white stripe wire in cavity 16 and remove the terminal from the connector.
14. Locate the white wire in cavity 19 and remove the terminal from the connector.
15. Install the terminal of the black/white stripe wire of P/N 12167673 in cavity 16 of the PCM connector.
16. Install the terminal of the white wire of P/N 12167673 in cavity 19 of the PCM connector.
17. Cut the terminals from both the black/white stripe and white wires from the original wiring harness.
18. Strip about 13 mm (1/2 in) of insulation from the two wires just cut and the wires from the new P/N 12167673.
19. Slide a piece of heat shrink tubing over one of the white wires just stripped.
20. Using the proper crimping tool and the splice clips included in the kit, crimp the splice clip over the bared ends of the white wires.
21. Slide a piece of heat shrink tubing over one of the black/white wires previously stripped.
22. Using the proper crimping tool and the splice clips included in the kit, crimp the splice clip over the bared ends of the black/white wires.
23. Solder the previously crimped splices.
24. Slide the heat shrink tubing into place over the splices. Using the proper heat tool, shrink the tubing around the wires and splices.
25. Route the wires to the wiring harness so the capacitor is placed under the convoluted tubing and tape the wires. The excess wires may be safely stored within the confines of the convoluted tubing.
26. Replace the CPA to the PCM connector.
27. Reposition the connector cover to the back of the connector and insert the tie straps which were included in the kit. Tighten them and trim the excess.
28. Install both connectors to the PCM.
29. Tighten the harness retainers.

Tighten
Tighten the retainers to 8 N·m (71 lb in).

30. Properly reposition the PCM into the air cleaner housing.
31. Install the air cleaner filter element.
32. Position the rear half of the air cleaner box and air duct to the throttle body.
33. Install and tighten the two air cleaner screws.

Tighten
Tighten the screws to 4 N·m (35 lb in).

34. Connect the intake air temperature sensor wire.
35. Remove the fender cover and close the hood.
36. Connect the negative battery cable to the battery.
37. Properly reposition rear seat in the vehicle.

Parts are currently available from GMSPO.

For vehicles repaired under warranty, use: