For 1990-2009 cars

# MIL Service Engine Soon Light On with No Gear DTCs Present After Transaxle Assembly or Gear Sets Replacement

Subject: | (MIL) SERVICE ENGINE SOON Light On with "No Gear" Diagnostic Trouble Codes (DTCs) Present After Transaxle Assembly or Gear Set(s) Replacement (Verify Correct Transaxle Assembly, Gear Set(s), or PCM Calibration Installation)

Models: | 1991-1999 Saturn vehicles equipped with MP6 or MP7 Automatic Transaxles

### Condition

Vehicle may set DTCs after replacing the complete transaxle assembly, individual gear components, or after reprogramming PCM.

The following DTCs may be set:

1991-1995 DTCs 16, 18, 21, 23 and/or 24

1996 - 1999 DTCs P0730, P0731, P0732, P0733, and/or P0734

### Cause

Two possible causes exist for this condition:

• | If the incorrect transaxle assembly or great components have been installed, the PCM calibration will not match the actual gear ratios and DTCs will set to indicate a gear is not available.

• | If the incorrect calibration has been installed due to a wrong VIN in the PCM, a gear ratio table may be used by the PCM which will not match the actual gear ratio(s) and result in DTCs setting

### Correction

Several repairs may be available to fix this concern depending on what cause is identified. One of the following repairs may be required:

### Procedure

• | If the wrong transaxle has been installed, remove it and install the appropriate model year or model type (MP6/MP7). Available PCM calibrations will not be accommodate mismatched engine and transaxle combinations.

- | Check the 10 character stamp on the top of the converter housing. The 1st position indicates the model year (i.e. 6 = 1996, V or 7 = 1997, W=1998, X = 1999). Positions 2-4 will indicate the model type (MP6/MP7).

- | if the vehicle is an SL, SL1, SW1, or SC1; a MP6 transaxle must be installed.

- | If the vehicle is an SL2, SW2, or SC2; a MP7 transaxle must be installed.

• | If incorrect gear set components have been installed, remove and install the proper gear set components. Check the part number of the gear that was installed and/or count the number of teeth on the gear and compare to the chart below.

• | If the incorrect calibration or VIN information has been written to the PCM, reprogram the PCM with the proper VIN and calibration information. Compare VIN plate on dash to VIN identified in the PCM.

- | In some programming errors, an incorrect VIN may be written to a PCM and subsequently calibrated with the wrong engine/transaxle calibrations.

- | If the gear ratio tables in the calibration are incorrect for that transaxle model type or year, the PCM will not recognize the gear ratios of the actual gear sets in the transaxle and will result in DTCs setting.

Gear Tooth Counts by Model Year Application

| 1st Drive | 1st Driven | 2nd Drive | 2nd Drive | 3rd Driven | 4th Drive | 4th Driven | Rev. Idler | Output | Ring Gear
91-93 MP6 1st Design* | 21 | 47 | 30 | 38 | 37 | 30 | 42 | 25 | 15 | 62
93-94 MP6 2nd Design** | 19 | 48 | 30 | 38 | 37 | 30 | 42 | 25 | 15 | 62
91-94 MP7 | 19 | 48 | 27 | 42 | 33 | 34 | 40 | 28 | 15 | 62
95-99 MP6 | 19 | 48 | 30 | 38 | 37 | 30 | 42 | 28 | 16 | 65
95-99 MP7 | 19 | 48 | 27 | 42 | 33 | 34 | 40 | 28 | 16 | 65

* Vehicles built prior to and including 1993 VIN PZ156139

** Vehicles built after and including 1993 VIN PZ156140

### Parts Requirements:

Refer to the appropriate section of the 91-99 Parts and Illustration

### Claim Information

To receive credit for this repair during the warranty coverage period, submit a claim through the Saturn Dealer System using the appropriate Electronic Labor Time Guide and Labor Operation Codes.