Grand Cherokee 2WD L6-4.0L VIN S (1997)
control engagement of the fourth gear overdrive clutch, the converter clutch, and governor pressure. Normal resistance value for the thermistor at
room temperature is approximately 1000 ohms.
The Powertrain Control Module (PCM) prevents engagement of the converter clutch and overdrive clutch, when fluid temperature is below
approximately 10°C (50°F).
If fluid temperature exceeds 126°C (260°F), the PCM causes a 4-3 downshift and engage the converter clutch. Engagement is according to the
third gear converter clutch engagement schedule.
The overdrive OFF lamp in the instrument panel illuminates when the shift back to third occurs. The transmission will not allow fourth gear
operation until fluid temperature decreases to approximately 110°C (230°F).
The thermistor is part of the governor pressure sensor assembly and is immersed in transmission fluid at all times.
Vehicle Speed and Distance Sensor
VEHICLE SPEED AND DISTANCE SENSOR-PCM INPUT
Fig. 11 VSS Location - 2WD
Fig. 12 VSS Location - 4WD
The vehicle speed sensor is located on the speedometer pinion gear adapter. The pinion gear adapter is located on the extension housing of the
transmission (drivers side-2WD), or on the transfer case (4WD). The sensor input is used by the powertrain control module (PCM) to determine
vehicle speed and distance traveled.
The speed sensor generates 8 pulses per sensor revolution. These signals, in conjunction with a closed throttle signal from the throttle position
sensor, indicate a closed throttle deceleration to the PCM. When the vehicle is stopped at idle, a closed throttle signal is received by the PCM (but
a speed sensor signal is not received).
