EXPERTEC TSB (91-T-29-SATURN)

Publication date: 1991-08-08
Reference number: 91-T-29-SATURN

EXPERTEC TSB

TECHNICAL SERVICE BULLETIN

Reference Number(s): 91-T-29-SATURN, Date of Issue: 08/08/91

RATTLE FROM ENGINE COMPARTMENT - VEHICLE NOISY AND/OR CHUGGLES

Model(s): 1991 Saturn W/MP6/MP7 Automatic Transaxles

Bulletin No.: Saturn 91-T-29

Date: 08/08/1991

BULLETIN ILLUSTRATION LIST

Fig 1: Graphic

Fig 2: Graphic

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.

SERVICE INFORMATION

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.

Fig 3: SERVICE PCM/TC CALIBRATIONS TABLE

NOTE: Engine and transaxle calibrations are certified and released in pairs.

To select the proper engine 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.

Fig 4: PARTS REQUIREMENT

To receive credit for this repair, submit a claim through the Saturn Dealer System as follows:

Fig 5: CLAIM INFORMATION TABLE

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