Majestic L6-4.0L (1990)
Control Module: All Technical Service Bulletins
MIL ON - A/T in Limp Home Mode
MODEL: Sedan Range (4.0L) up to 93 MY
Automatic Transmission - Defaults To "Limp Home" in Wet Weather - Repair Procedure
The Transmission Failure malfunction indicator lamp (MIL) illuminates and the transmission defaults to the "Limp Home" mode during rain or after
using a car wash.
Water can enter the vehicle through the engine management harness grommet in the vacuum tank under the battery tray. The water can drip onto the
Transmission Control Module (TCM) causing it to illuminate the transmission MIL and default to the "Limp Home" mode.
If 4.0L Sedan Range vehicles up to 1993 MY (VIN 667829) illuminate the transmission MIL and default to "Limp Home" mode during rainy weather or
after using a car wash, seal the EMS harness grommet as described below.
Record the preset radio stations (including X-mem) and remove the battery from the vehicle.
Remove the battery tray, disconnect the EMS harness from the vacuum tank and remove the vacuum tank
Inject a liberal amount of Bostik Alpha Seal 132 or an equivalent sealant into the areas shown in Illustration 1.
A. - Around the vacuum tank inner recess for the grommet
B. - Around the EMS harness at the front and back of the grommet
C. - Between the EMS harness grommet and the body panel face
Replace the vacuum tank and press down firmly to squeeze the sealant around all of the joints
Clip the EMS harness into place.
Reassemble the battery tray before the sealant sets. Torque the mounting bolts to 12 - 16 lb ft (15.5 to 20.5 Nm).
Install the battery, code the radio, and reset the radio stations and clock
Bostik Alpha Seal 132 or equivalent - source locally
Source sealant locally