NO FOURTH GEAR THM200-4R AND THM 325-4L DIAG. PROCEDURE. Cadillac DeVille 1982

NO FOURTH GEAR - THM 200-4R AND THM 325-4L

Some 1982 and 1983 Cadillacs equipped with THM 200-4R and THM 325-4L transmissions may experience a no fourth gear condition. (On DFI equipped vehicles, codes 29 and/or 39 could also be present.) This condition can be caused by a broken hub weld on the overrun clutch housing (refer to Figure 1).

When diagnosing vehicles exhibiting this condition, test drive the vehicle applying a light throttle in drive range to about 30-35 MPH (third gear). Move the selector lever into manual second and release the throttle. The transmission should downshift and coastdown overrun braking should occur.

1. If coastdown overrun braking does occur, refer to the diagnosis procedure for no fourth gear in the Service Information Manual.

2. If coastdown overrun braking does not occur, remove the transmission from the vehicle. Inspect the overrun clutch housing for a break in the hub weld. If the hub weld is broken, the cause is due to misaligned pinions in the overdrive carrier.

In all instances where the hub weld is broken on the overrun clutch housing, both the overrun clutch housing (Figure 1) and the overdrive carrier (Figure 2) must be replaced. Use part numbers as listed below:

Overrun Clutch Overdrive Transmission Housing P/N Carrier P/N

200-4R 8634107 8634117 325-4L 8635941 8635036

Object Number: 90877 Size: MF

Object Number: 93045 Size: MF

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.