A/T - Overheating Diagnosis
Number: 84-10Section: 7A (VIIc)
Date: Oct., 1983
Subject: TRANSMISSION OVERHEATING
Model and Year: ALL THM 700-R4
TO: ALL CHEVROLET DEALERS
Some THM 700-R4 transmissions may exhibit an overheating condition when the vehicle is driven in fourth gear (overdrive), and the torque converter clutch is not operational. Under these conditions, and especially under heavy load conditions, heat is generated in the torque converter that the transmission cooler cannot cool adequately.
When diagnosing any THM 700-R4 transmission for an overheating condition, the following conditions are some possible causes:
1. The speedometer not working properly on ECM controlled units.
2. A disconnected speedometer cable on ECM controlled units.
3. The transmission electrical connector was disconnected.
4. The torque converter clutch inoperative.
5. An inoperable ECM unit.
6. Refer to the appropriate torque converter diagnosis section in your service manual for additional information.
To prevent possible transmission overheating conditions, it is recommended that the THM 700-R4 transmission never be driven in fourth gear when the torque converter clutch is not operational. If the torque converter clutch is not operational or even suspected to be not operational, the vehicle should be driven in manual third range and the vehicle serviced.