A/T - No Fourth Gear Operation, DTC 29/39 Set

Bulletin No. T 83-69
File In Group 7
Number 65
Date April '83
NO FOURTH GEAR - THM 200-4R AND THM 325-4L

Figure 1 - OVERRUN CLUTCH:

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.

Figure 1 - OVERRUN CLUTCH:

Figure 2 - 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