RATTLE FROM ENGINE COMPARTMENT VEHICLE NOISY AND/OR CHUGGLES. Saturn Saturn 1991

For 1990-2009 cars

# RATTLE FROM ENGINE COMPARTMENT VEHICLE NOISY AND/OR CHUGGLES

#### SUBJECT: Rattle From Engine Compartment, Vehicle Noisy and/or Chuggles at 30-40 MPH (Service Calibration) All 1991 Saturns with MP6/MP7 Automatic Transaxles

#### CONDITION:

---------- Some customers may comment on a rattle coming from the engine compartment. A comment may also be made that the vehicle is noisy or chuggles between 30 to 40 mph, in third or fourth gear, during a light throttle going up a slight grade.

#### CAUSE:

------- The rattle noise in the transaxle can be caused by normal gear clearances being vibrated by normal engine rotation vibration. This rattle has no affect on transaxle performance.

#### CORRECTIVE ACTION:

#### NOTE: Determine what transaxle is on the vehicle, then refer to the following chart before proceeding to the procedures in this bulletin.

*NOTE: MP7 transaxles with a change code of "1" or greater, and all MP6 transaxles have the new reverse idler gear system installed during production.

A new powertrain control module (PCM) calibration has been released for service that helps eliminate this rattle condition. This service PCM calibration modifies the shift schedules, causing shifts and torque converter clutch (TCC) engagements to occur at higher vehicle speeds.

The new service PCM/TC calibrations are:

- SOHC(LKO) MP6 Trans. EEPROM 4960 - DOHC (LLO) MP7 Trans. EEPROM 4964

#### NOTE: Engine and transaxle calibrations are certified and released in pairs. To select the proper enginc calibration to use with these transaxle calibrations, refer to the "Selections" in the "Service Stall System."

Only vehicles built with the latest PCM can be reprogrammed with the new calibration. Vehicles with earlier versions of the PCM require replacement of the PCM before reprogramming.

To determine if the PCM can be reprogrammed with this service calibration, check the TCM ID TABLE with the portable diagnostic tool (PDT) or the service stall system (SSS). If the TC EPROM SW ID is 4666 the PCM will have to be replaced. The new version of the PCM will have a TC EPROM SW ID of 1465.

If the PCM has to be replaced, refer to the "Powertrain Control Module" removal and installation procedures in the "Powertrain Control Module" section of the "Electronic Engine Controls Service Manual."

If the TC EPROM SW ID is 1465, refer to "Reprogramming EEPROM" in the "System Utilities" section of the "Service Stall System (SSS) User Guide" for procedures on reprogramming with the service calibration.

#### PARTS REQUIREMENT:

21021221 Powertrain Control Module Assembly-Engine Gas, 4 Cyl, 1.9L, TBI, SOHC (LKO)-Auto. Trans. MP6 21021220 Powertrain Control Module Assembly-Engine Gas, 4 Cyl, 1.9L, MFI, DOHC (LLO)-Auto. Trans. MP7 CLAIM INFORMATION: ------------------- To receive credit for this repair, submit a claim through the Saturn Dealer System as follows:

Labor Case Operation Type Description Code Time ---- -------------------- -------- ------- VW EEPROM Reprogram T9547 0.3 hrs VW Controller, PCM-Replace T9550 0.3 hrs

When returning PCM, include the following information: "PCM replaced for transaxle service calibration."

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.