Description & Operation
Transmission is a fully automatic 3-speed transmission with an overdrive unit attached to rear of transmission. The 1st through 3rd gears are provided by clutches, bands, overrunning clutch and planetary gear set. The overdrive or 4th gear is provided by overdrive clutch, direct clutch, planetary gears and overrunning clutch in overdrive unit. Transmission contains front and rear bands, front clutch, rear clutch and overrunning clutch. The overdrive unit contains overdrive clutch, direct clutch and overrunning clutch. See Fig 1 .
Overdrive or 4th gear operation is controlled by a manually operated overdrive switch on the instrument panel. Overdrive switch is in the electrical circuit with overdrive solenoid on the valve body and Powertrain Control Module (PCM). Transmission will not shift into overdrive if switch is not in the ON position. Torque converter lock-up is activated when the PCM provides voltage to lock-up solenoid located on the valve body. For electronic diagnosis of RH-type transmissions, see AUTO TRANS DIAGNOSIS - 42RH, 46RH & 47RH article. For information on 1995 Jeep Grand Cherokee equipped with 42RE, see the AUTO TRANS DIAGNOSIS - 42RE W/TCM article. For electronic diagnosis information for Dodge models with RE-type transmissions without TCM, see AUTO TRANS DIAGNOSIS - 42, 44, 46 & 47RE W/O TCM article.
On 46/47RE transmissions, governor pressure used for transmission shifting is controlled electronically. Various sensors and Transmission Control Module (TCM) are used for controlling the governor pressure. Overdrive or 4th gear operation is controlled by a manually operated overdrive switch on the instrument panel. Overdrive switch supplies input signal to the TCM for controlling overdrive operation.
For 1995 Grand Cherokee models, the TCM contains a self-diagnostic system which will store a Diagnostic Trouble Code (DTC) if a problem or failure exists in the electronic system or components. Diagnostic trouble code can be retrieved to determine the transmission problem area. For information on 1995 Jeep Grand Cherokee equipped with 42RE, see the AUTO TRANS DIAGNOSIS - 42RE W/TCM article.
On Pickup applications with Diesel engine and gasoline models with special auxiliary transmission oil cooler, overdrive or 4th gear operation and torque converter lock-up are controlled by transmission fluid temperature sensor. Transmission fluid temperature sensor is located in oil cooler outlet line, near the transmission case. Transmission fluid temperature sensor monitors transmission fluid temperature and is in the circuit with the overdrive and lock-up solenoids on the valve body and the Powertrain Control Module (PCM).
Transmission fluid temperature sensor prevents overdrive or 4th gear operation when transmission fluid temperature is less than 60°F (15°C). Transmission fluid temperature sensor prevents torque converter lock-up operation when transmission fluid temperature is less than 70°F (21°C). Transmission fluid temperature sensor will either downshift transmission to 3rd gear or prevent a 3-4 upshift when transmission fluid temperature exceeds 270-275°F (132-135°C).